VNSA3 Flashcards
1
Q
Define anatomy
A
Physical structure of the body
2
Q
Define physiology
A
Way in which the body systems work
3
Q
Define ventral
A
Towards the belly or lowermost surface of the animal
4
Q
Define dorsal
A
Towards the back of the animal
5
Q
Define caudal (posterior)
A
Towards the rear or tail end of the animal
6
Q
Define cranial (anterior)
A
Towards the front or head of the animal
7
Q
Define Rostral
A
Towards the nose
8
Q
Define proximal
A
Towards the body
9
Q
Define distal
A
Away from the body
10
Q
Define palmar
A
Rear surface of the front paw
11
Q
Define plantar
A
Rear surface of the hind paw
12
Q
Define dorsal paw
A
Front aspect of either paw
13
Q
Define medial
A
Closer to the median plane or midline of the animal
14
Q
Define lateral
A
Away from the median plane or midline of the animal
15
Q
Define sternal/ventral recumbency
A
On its stomach
16
Q
Define dorsal recumbency
A
On its back
17
Q
Define lateral recumbency
A
On its side
18
Q
Define
Median or sagittal plane
A
Divides the body into L and R
19
Q
Define
Transverse plane
A
Perpendicular to long axis of the body cutting it into front and back
20
Q
Define
Dorsal plane
A
Parallel to back cutting into top and bottom
21
Q
Define
Para-sagittal plane
A
Parallel to median plane moving more laterally
22
Q
Define contralateral
A
Affecting the opposite side
23
Q
Define ipsilateral
A
On the same side
24
Q
Define deep
A
Closer to the centre of the body
25
Define superficial
Near to the surface of the body
26
Define Abduction
Movement away from the medial plane
27
Define adduction
Movement towards the medial plane
28
Define protraction and retraction
Protraction = to protrude or stick out a part of the body
Retraction = movement that brings a protracted body part back to its original position
29
Define supination and pronation
Supination = a motion toward the centre of the body (rolling foot inwards)
Pronation = a motion towards the outside of the body (rolling foot outwards)
30
What are the 3 body cavities ?
Thoracic
Abdominal
Pelvic
31
What structures are found within the thoracic
Lungs, heart, diaphragm, oesophagus, trachea, arteries and veins, thymus gland
32
What structures are found within the abdominal cavity?
Stomach, intestines, kidneys, liver, pancreas, gall bladder, spleen, adrenal gland, ureter and bladder
33
What structures are found within the pelvic?
Bladder, reproductive organs, colon, rectum, urethra
34
What does the pleura line
Thorax or thoracic cavity
35
What does the peritoneum line mean?
The abdominal cavity
36
What is the pleura and peritoneum?
A serous membrane.
Produces a watery fluid ensuring friction free movement between the surfaces of the cavity and organs/structures within it.
37
What is parietal and visceral
Parietal = serous membrane lining the boundaries or sides (walls) of the cavity
Visceral = serous membrane covering the organs (viscera) within the cavity
38
What are the boundaries of the thoracic cavity ?
Cranially = thoracic inlet: first thoracic vertebrae, fist pair of ribs and cranial end of sternum
Caudally = diaphragm
Dorsally = thoracic vertebrae and hypaxial muscles
Ventrally = sternum
Laterally = ribs and intercostal muscles
39
What is the central space between the thoracic cavity called ?
Mediastinum
Containing: the heart, trachea, oesophagus and major blood vessels
40
What are the boundaries of the abdominal cavity?
Cranially = diaphragm
Caudally = pelvic inlet
Dorsally = lumbar vertebrae
Ventrally = abdominal muscles
Laterally = abdominal muscles
41
Define omentum
A lacy sheet of peritoneum from the stomach extending to the caudal abdomen
42
Define mesentery
The visceral peritoneum associated with the small intestines
43
What are the boundaries of the pelvic cavity ?
Cranially = pelvic inlet
Caudally = pelvic outlet
Dorsally = sacrum
Ventrally = floor of pelvis
Laterally = lateral walls of the pelvis
44
MRS GREN
Movement
Respiration
Sensitivity
Growth
Reproduction
Excretion
Nutrition
45
Levels of organisation (smallest to largest)
Cell, tissue, organ, organ system, organism
46
Cell or plasma membrane
Provides structure surrounding the cell
Semi-permeable
Approx 8nm wide
Made up of phospholipid bilayer containing protein and carbohydrate molecules
47
Define free entry
(Semi-permeable)
Some substances can pass through the membrane easily
48
Define entry via protein transport system
(Semi-permeable)
Some substances can pass through the membrane via the protein transport system, providing some control
49
Define excluded
(Semi-permeable)
Some substances are prevented from entering the cell
50
What is passive transport ?
Across a gradient of concentration, pressure or electrical charge, no energy required
51
What is diffusion ?
Movement of molecules from an area of high concentration to low concentration through a semi-permeable membrane.
Small molecules (O2, CO2, H2O) can pass freely through the pores, same for lipid soluble substances.
52
What is facilitated diffusion?
Passive movement of large molecules/ions across a semi-permeable membrane, from an area of high concentration to low concentration with the use of proteins
53
What is osmosis?
Movement of water from an area of low concentration to an area of high concentration through a semi-permeable membrane, when large molecules cannot get through.
54
What is active transport?
Requires energy to transport molecules (glucose/amino acids) or ions (sodium/potassium) across a cell membrane, against concentration gradient.
Energy is provided by glycolysis.
ATP is converted into ADP, releasing energy
Then used to ‘push’ the substance against the concentration gradient.
55
What is endocytosis ?
Material taken into the cell
56
What is exocytosis ?
Material removed from the cell
57
What can be seen under a light microscope ?
Nucleus, vacuoles, cell membrane, cytoplasm.
58
What can be seen under an electron microscope?
All cell parts
Lysosomes, Golgi vesicles, ribosomes, RER, SER, cell membrane, cytoplasm, microtubules, centrioles (centrosome), nucleus, nucleolus, Golgi apparatus, mitochondria.
59
What are somatic cells
All cells in the body except for reproductive cells
Replicate by mitosis and contain diploid number of chromosomes.
60
What are germ cells?
Reproductive cells - sperm and ova
Replicate by meiosis and contain a haploid number of chromosomes
61
Mitosis
( I paid my aunt twice)
Interphase
Prophase
Metaphase
Anaphase
Telophase
62
Interphase
(Mitosis)
Known as the ‘resting phase’
Cells grow and prepare for next division
Chromosomes become more visible
63
Prophase
(Mitosis)
Nuclear membrane breaks down
Chromosomes replicate
Identical pairs of chromatids remain joined at the centromere
Centrioles move to opposite ends and from spindle fibres
64
Metaphase
(Mitosis)
Chromosomes line up at the equator of the cell
Chromatids start to pull apart at the centromere
65
Anaphase
(Mitosis)
Chromosomes attach to the spindle, which then contracts
Chromatids pulled to opposite ends of the cell
66
Telophase
(Mitosis)
Spindles break down and nuclear membrane reforms
Cell constricts separating into 2 cells
Cytokinesis
(2 identical daughter cells with diploid number of chromosomes, they unravel)
67
Meiosis
Interphase
Prophase I
Metaphase I
Anaphase I
Telophase I
Prophase II
Metaphase II
Anaphase II
Telophase II
68
Interphase
(Meiosis)
2 pairs of identical chromosomes
69
Prophase I
(Meiosis)
Each chromosome replicates, crossing over may occur
70
Metaphase I
(Meiosis)
Chromatids arrange in pairs along the equator of the cell
71
Anaphase/telophase I
(Meiosis)
Chromatids migrate to the syncytium poles and the cell starts to divide
(First meiotic division, cytokinesis - 2 identical daughter cells, each containing the diploid number of chromosomes)
72
Prophase II
(Meiosis)
Transitory, no chromosome replication
73
Metaphase II
(Meiosis)
Chromosomes arrange themselves along the equator of the cell and fibrous spindles form.
74
Anaphase II
(Meiosis)
Chromatids migrate to the poles
75
Telophase II
(Meiosis)
Each cell divides and the nuclear membrane begins to form
(2nd meiotic division - cytokinesis - 4 identical daughter cells form each containing haploid number of chromosomes. These cells are not identical to the parent cell).
76
Fluid is present in the body in a variety of forms
Define - Intracellular
Inside cells
77
Fluid is present in the body in a variety of forms
Define - extracellular
Interstitial
Extracellular fluid that surrounds the cells
78
Fluid is present in the body in a variety of forms
Define - intravascular
Found in the vascular system
(Blood)
79
Normal water loses for cats and dogs
Urine - 20mls/kg/day
Faeces - 10-20mls/kg/day
Respiration and sweating - 20mls/kg/day
80
Water requirements
Cats, dogs, rabbits
Cats and dogs - 50-60mls/kg/day
Rabbits - 100ml/kg/day
81
About the cell membrane
- permeable to small molecules
-larger molecules cannot pass through
-movement of water is controlled by the osmotic and hydrostatic pressure (they oppose each other)
82
Passive transport - simple diffusion
Water, dissolved gases or lipid-soluble molecules move from an area of HIGH concentration to an area of LOW concentration.
83
Passive transport - OSMOSIS
Diffusion of water across a semi-permeable membrane from an area of LOW sugar concentration to an area of HIGH sugar concentration to reach equilibrium. The water has to move as the sugar cannot pass through the membrane as it’s too large.
84
Name the osmotic pressures in the body
Hypertonic
Isotonic
Hypotonic
85
Define renation
Water leaves faster than it enters
86
Define lysis
Water enters cells rapidly, can cause cells to burst
87
Atoms
- have no electrical charge
-if they gain a charge they become ions
-if they lose a charge they become positively charged
-if they gain a charge they become negatively charged
88
Positive ions
Called cation
(Sodium Na+, potassium K+, calcium Ca+2, magnesium Mg+2, iron Fe+2 and hydrogen H+)
89
Negative ions
Called anion
(Chloride Cl- , bicarbonate HCO3- , sulphate SO4-2 , phosphate HPO4-2 and protein anions
90
Electrolytes
Chemicals that dissolve, or split in water forming positive and negative ions (an element that carries an electrical charge)
Help regulate the osmosis of water between water compartments. Some are involved in acid-base regulations
91
pH levels
pH 7 is neutral
pH greater than 7 is alkaline
pH less than 7 is acid
Normal pH of blood is 7.35-7.45
If pH falls below 7.35 acidaemia exists
If pH is greater than 7.45 alkalaemia exists
92
Acidosis and alkalosis
Both terms describe abnormal processes and conditions that cause acidaemia or alkalaemia.
Acidosis and alkalosis can exist without acidaemia/alkalaemia bcs of the body’s secondary compensatory mechanisms.
It is essential for proper cellular function that the blood pH is kept within normal range.
The body has various mechanisms for dealing with hydrogen ions that are produced within the body to prevent dramatic fluctuations in pH.
(Buffers, respiratory response, renal response).
93
Acid-based regulations
Buffering
Buffers react with acids to limit the pH change that they would normally produce.
buffers trap hydrogen (H+) ions, preventing the pH (e.g bicarbonate and phosphate)
These are classed as extracellular buffers
94
Acid-based regulations
Respiratory system
Carbon dioxide is dissolved in the body fluids as increasing respiration removes carbon dioxide from the body anf therefore raises pH.
Decreasing respiration increases carbon dioxide and therefore lowers pH
95
Acid-based regulations
Renal system
Bicarbonate (a buffer) can be generated within the cells of the kidney, neutralising H+ ions.
The kidney will also increase the amount of H+ ions that are excreted in urine, removing H+ ions.
96
Acidosis
Respiratory and metabolic
Respiratory = impaired ventilation, inspired carbon dioxide, increased carbon dioxide production
Metabolic = accumulation of H+, ruptured bladder/blocked urethra, diabetic keto-acidosis, chronic diarrhoea
97
Alkalosis
Respiratory and metabolic
Respiratory = over ventilation
Metabolic = loss of H+, over administration of sodium bicarbonate
98
What is a tissue?
A group of similar cells that function together to perform a specialised activity.
Every tissue is made up of 3 elements:
-cells
-intercellular products
-interstitial fluid
99
What is the study of tissue called?
Histology
100
What are the 4 main types of tissues in the body?
-muscle
-nervous
-epithelial
-connective
(Mum never eats cake)
101
Epithelial tissue
Covers all internal and external surfaces of the body.
Functions = protection, secretion, absorption
2 main divisions = covering/lining and glandular
Epithelium is classified according to how many layers of cells it contains and the sub-divided again depending on the types of cells it contains
102
Define simple epithelium
Epithelium is 1 cell thick
103
Define stratified or compound epithelium
Epithelium with 2 or more layers of cells.
104
Define simple squamous
-single sheet of thin, flattened cells on a basement membrane
-very thin and delicate
-found in areas where diffusion occurs
105
Define simple cuboidal
-one layer of cube shaped cells
-found lining many glands and ducts (kidney tubules, respiratory bronchioles)
-often has a secretory or absorption role
106
Define simple columnar
-tall and rectangular cells
-found lining many tissues with absorptive functions and secretory functions.
(Lines the intestines - aids in absorption of soluble food material).
107
Define ciliated
-more specialised, normally columnar epithelium
-free surface of cells have tiny hair like projections
-cilia on surface of each cell, increasing their surface area
-lines tubes and cavities where materials must be moved (respiratory tract and oviducts)
108
Define stratified (compound) epithelium
Dependant of the type of cells within the epithelium’s top layer, this can be stratified squamous, cuboidal or transitional.
-series of layers make it very tough (protective)
-found in areas subject to friction and wear (oesophagus, mouth, rectum)
-in abrasive areas, it’s strengthened further by infiltration with protein and keratin (keratinised) found on thr pads and skin
109
Define pseudostratified epithelium
Gives multiple layered appearance, but only single
Nuclei irregularly placed
110
Define transitional epithelium
-specialised stratified epithelium (many layers)
-found in structures that stretch and distend (bladder and ureters)
-appearance of cells will change according to distension of the structure
111
Define glandular epithelium
-columnar epithelium containing goblet cells
-goblet cells secrete materials into the cavity or space they are lining
-folding of glandular epithelium results in formation of a gland
-secretions from glands include enzymes, mucus, milk, sweat, tears, wax and saliva
112
Define endocrine glands
Secretions enter extracellular fluid and then diffuse directly into the bloodstream without flowing through a duct. These secretions are called hormones and regulate many metabolic and physiological activities to maintain homeostasis.
Develop from epithelium tissue, but separated from epithelium surface
113
Define exocrine glands
Secretions flow onto the free surface of the epithelium, usually via tube-like ducts.
(Sweat and salivary glands)
‘Pockets’ in epithelial tissue
Ducts connecting onto the surface
Variety of shapes
114
Define adenoma
Benign tumor
Formed from the glandular structures.
115
Type of exocrine gland
-sweat/sudorific gland
-mribomian (eye) gland
- 4 salivary glands
-anal gland
-mammary gland
-gastric/fundic (stomach)
-Brunners (duodenum)
-sebaceous
116
Type of exocrine gland
-pituitary
-thyroid
-adrenal medulla
-adrenal cortex
-islets of Langerhans (pancreas)
-ovaries
-parathyroid
-testes
117
Define connective tissue
Responsible for supporting and binding together all the organs and tissues of the body. It forms the transport system carrying nutrients around the body and removing waste.
Connective tissue consists of a ground substance or matrix, with cells and fibres embedded within the matrix.
118
What are the 2 types of fibres in connective tissue?
Collagen = gives strength to tissues (secreted by fibroblasts)
Elastic = allows stretching
119
Define loose connective tissue
Most common type of connective tissue
120
Define areolar connective tissue
Found all over the body
Lots of cells arranged in a loose irregular network of fibres
Contains - loose network of 2 types of protein fibres (collagen and elastic) , some adipose cells, varying numbers of macrophages.
Forms subcutaneous tissue of the skin and is located between organs
Protective function
121
Define adipose tissue
Similar structure to areolar but contains a greater number of fat cells
Functions: energy source, insulator against heat loss, protective role around the kidney and eye, food reserve
122
Define dense connective tissue
2 types = regular or irregular
The name refers to the arrangement of the collagen and elastic fibres within the tissue
Parallel - regular
Irregularly interwoven - irregular
This tissue contains large number of fibres in proportion to the number of cells within the matrix.
123
Define regular fibrous/dense connective tissue
Collagen fibres are parallel
Forming strong bands of fibrous tissue (tendons and ligaments)
Tendons connect - muscle to bone
Ligaments connect - bone to bone
124
Irregular fibrous/dense connective tissue
Forms sheets of connective tissue
Fascia and aponeuroses
Fibres are irregularly arranged - making the tissue impact resistant, bearing stress in all directions
125
Define cartilage
A specialised connective tissue
Rigid, yet flexible and able to bear weight.
It’s avascular, no blood supply.
Nutrition is supplied by perichondrium (fibrous connective tissue covering the cartilage)
Consists of:
-gel like ground substances
- fibres
-chondrocyte cells
126
Name the 3 types of cartilage
Hyaline
Elastic
Fibrocartilage
127
Define hyaline cartilage
-simplest and commonest form of cartilage
-chondrocytes within a hyaline matrix fine with collagen fibres, randomly arranged
-appears bluish-white and translucent
Found on articular surfaces or joints
-smooth surface for joint movement
-absorbing some of the forces placed on the joint
-also found on nose, larynx, trachea, bronchi and embryo skeleton
Function - covers the bone ends and provides a smooth surface to prevent friction.
128
Define elastic cartilage
Similar to hyaline, but as well as collagen fibres they also contain a large number of elastic fibres
Fibres run through the matrix at all directions
Function - support and flexibility
Found - external ear and epiglottis
129
Define fibrocartilage
Strongest form of cartilage
Higher number of collagen fibres in place of hyaline
Function - to give strength and tough support
Found - intervertebral discs, menisci of the stifle, attaches the tendons and ligaments to bone
130
Define bone
Ground substance containing collagen fibres and a protein (osteonectin) osteoid
Surrounded by fibrous membrane - periosteum
Calcium phosphate is deposited into osteoid
Bone hard and rigid - compact bone
Blood vessels and nerves run through the bone matrix - cancellous/spongy bone
131
Define haematopoietic tissue
Specialised connective tissue forming bone marrow in long bones
Jelly like consistency
Role - formation of blood cells
132
Define blood
Highly specialised connective tissue that circulates through the blood vessels
Role - supply oxygen and nutrients, remove waste to other organs for excretion
Consists of a number of different cells, fluid ‘ground substance’ , plasma
133
Name the 3 different types of muscle
-cardiac
-skeletal
-smooth
134
Define skeletal muscle
Voluntary movement
Provides movement of the skeleton
Consists of muscle cells - long and cylindrical in parallel
Fibres are grouped together in bundles - held by connective tissue
Whole muscle is enclosed by a connective tissue muscle sheath. Continuous with the tendons connecting it to the bone
135
Define smooth muscle
Involuntary movement
‘Visceral’ muscle , found in internal organs walls
Long, spindle shaped cells
Surrounded by connective tissue forming sheets
Nuclei in the centre of the cell - unlike striated muscle
No ‘stripes’ hence smooth muscle
136
Define cardiac muscle
Involuntary
Makes up the myocardium
Responsible for heart contractions - under the control of the autonomic nervous system
Cells are cylindrical as striated muscle
Fibres branch creating a ‘network’ - linked by intercalated discs
Centrally placed by nucleus
137
Define nervous tissue
Main cell within the nervous tissue is a neuron
- transmits nerve impulses from one area to another
Multiple neurons and synapses make up nerve pathways
-neuromuscular junction: muscle fibre
138
Define exoskeleton
An outside skeleton, arthropods (spiders, crustaceans, insects and crabs).
139
Define endoskeleton
An inside skeleton, vertebrates
140
What does the structure of bone consist of.
1. Osteocytes sitting in lacunae in the matrix
2. Cell types
3. Matrix comprised of abundant mineral salts and collagen fibres
141
Define osteoblasts
Forms bone tissue
142
Define osteocytes
Maintains bone tissue
143
Define osteoclasts
Functions in resorption.
The destruction of bone matrix
144
Compact bone
-in the cortex
-outer compact bone = very hard, formed by concentric layers (lamellae) that surround small holes (Haversian systems).
-A Haversian canal surrounded by concentric lamellae forms a unit called osteon.
-osteons = packed together to form compact bone
- 1 osteon = Haversian system
145
Cancellous bone
AKA - spongy bone
-located beneath compact bone
-consists of meshwork of bony bars (trabeculae) with many interconnecting spaces containing bone marrow.
146
Medulla
-mainly contains yellow marrow in adults, red marrow in young.
-periosteum = membrane covering bone except where articular cartilage is present.
-innervation and blood supply
-long bones = via nutrient epiphyseal and periosteal artery and vein
-rich nerve supply accompanies blood vessels and are present in periosteum.
147
What is epiphysis ?
End of a long bone where bone growth takes place
148
What is diaphysis?
Shaft of a long bone
Function = to transport oxygen and immune support, mineral and fat storage
149
What is metaphysis ?
Part of a long bone
Contains growth plate of the epiphysis
150
Bone formation: endochondral ossification
-bone develops first as hyaline cartilage in the embryo, then becomes ossified
1. A hyaline cartilage model is made in the embryo
2. Primary centres of ossification appear in the centre of the diaphysis of the bone
3. Osteoblasts are laying down bone to replace the cartilage
4. Gradually extends towards the ends of the bone
5. Secondary centres of ossification appear in the epiphysis
6. Osteoblasts are also laying down new bone
7. Primary and secondary centres of ossification eventually meet at a band of cartilage called the epiphyseal growth plate.
8.the epiphyseal growth plate produces new cartilage on the epiphyseal side, thus steadily elongating the bone.
9. The cartilage cells on the diaphysis side are converted to bone by osteoblasts
10. Still happening
11. Osteoclasts start to remove some of the new bone tissue from the centre of the diaphysis to form the marrow cavity
12. Once the bone reaches its full length, the cartilage cells in the growth plate stop dividing
13. No further growth is possible
151
Bone formation : intramembranous ossification
-osteoblasts lay down bone between 2 layers of fibrous connective tissue
-there is no cartilage template (eg-skull)
152
Parathyroid hormone role in bone homeostasis
-increases activity of osteoclasts, calcium is released into the blood stream from the breakdown of bone. Inhibits osteoblasts.
-increases rate phosphate is excreted by the kidney, causing release of calcium and phosphate from the bone
153
Vit D/calcitriol (precursor) role in bone homeostasis
-increases calcium levels in blood through reabsorption in the gut and kidney
-promotes osteoclast activity
154
Calcitonin (thyroid c cells)
-has the opposite effect
-decreases the activity of osteoclasts and so blood levels of calcium fall
-increases activity of osteoblasts so more calcium is stored.
155
Fracture repair
1. Inflammatory phase = with haematoma formation
2. Repair phase = a fibrocartilage callus is formed and trabecular bone is laid down
3. Remodelling phase = the trabecular bone is replaced with compact bone
156
Healing bones
Direct healing = bone edges close enough to not require the formation of a callus, often requires surgical stabilisation
Indirect healing = a callus forms, initially the response is similar to other tissues (haemorrhage, clot formation and acute inflammation)
157
Name the bone types
-long
-short
-flat
-irregular
-sesamoid
-pneumatic and splanchnic
158
Long bones
-connected with large movement
-have a diaphysis and 2 epiphyses
-epiphysis = the two ends of the bone
-metaphysis = the region where the diaphysis meets the epiphysis.
-outer layer of compact bone
-inner medulla contains marrow
159
Short bones
-almost cube shaped
-associated with smaller, complex movements
-outer layer of compact bone
-core of cancellous bone
-no medullary cavity
-develop from 1 ossification centre
-carpal and tarsus bones
160
Flat bones
-protect internal organs
-flat in shape
-compact bone outer cortex
-cancellous bone inside
-no medullary cavity
-stretch out in 2 directions as they grow
-skull bones, scapular and ribs
161
Irregular bones
Structure is similar to short bones, but they are irregular in shape
-vertebrae
162
Sesamoid bones
-sesame shape
-lie in tendons or occasionally ligaments over bony prominences
-changing the course of the tendon, reducing wear
-patella
163
Pneumatic bone
-contain air filled spaces within medullary cavity
-reduces the weight
-frontal sinus and avian skeleton
164
Splanchnic bone
-develop within soft tissue
-unattached from the rest of the skeleton
-os penis
165
Functions of the skeleton
-support
-protection
-leverage
-attachment of skeletal muscle
-storage
166
Functions of the skull
-houses and protects the brain
-houses and protects special senses (sight, smell, taste etc)
-houses dentition
-allows air and food entry
-attaches to hyoid apparatus
-attaches to masticatory and expression muscles
-communication
(Most skull bones are joined together by fibrous joints).
167
Nasal chambers
Nasal septum (cartilaginous plate dividing the nasal chambers lengthways, delicate ‘scrolls’ of bone)
Ethmoid bone (caudal boundary of the nasal chamber, separating it from the cranium)
Cribriform plate (sieve like area with numerous foramina, olfactory never pass nasal mucosa to brain)
Ventral nasal chambers - made up of the hard palate (incisive bone, part of the maxilla bone, palatine bone)
168
Condylar process
-temporomandibular joint
-coronoid process
-masseteric fossa
169
Hyoid apparatus
-lies in the intermandibular space
-made up of a number of small bones
-suspends tongue and larynx from base of skull
-articulates with the temporal region (cartilaginous joint)
-moves backwards and forwards (moving the larynx)
170
Skull shapes
Varies between species
More rounded in the cat, diff shapes for dogs (brachycephalic, dolichocephalic, mesocephalic/mesaticephalic)
171
Vertebrae
Cervical = neck
Thoracic = ‘chest’
Lumbar = lower back and abdomen
Sacral = pelvic area
Caudal/coccygeal = tail
Vertebral formula of cat and dog = C7, T13, L7, S3, C20-23
172
Functions of the vertebral column
-stiffen body axis
-protect spinal cord
-protects soft tissue ventral to spine
-insertion of muscles for movement
173
Basic vertebrae structure
-roughly cylindrical ventral body
-Cranially convex
-Caudally concave
-neural arch = neural or vertebral foramen (containing the spinal cord and link forming vertebral canal)
-the neural arch has a dorsal projection (spinous process), also lateral (transverse process)
-cranial and caudal edges of the neural arch (cranial and caudal articular process)
-various other processes- muscle attachment
174
Intervertebral discs
-tough fibrocartilage connective tissue
-‘shock absorber’
-connective tissue outer area (annulus fibrosus)
-gelatinous core (nucleus pulposus)
-ligaments join adjacent vertebrae
175
Cervical vertebrae
Atlas (C1) = no body or spinous process, 2 ‘winged’ lateral masses, articulates with occcipital condyles of the skull
Axis (C2) = elongated spinous process, nuchal ligament, Cranially is the dens/odontoid process
176
Thoracic vertebrae
Distinctive tall spinous process
Articular with the ribs via:
-costal fovea, forms synovial joint with head of rib
-transverse fovea, forms synovial joint with tubercle of rib
177
Lumbar vertebrae
Large bodies
Long transverse process extending cranioventrally
Lumbar muscles attach to the transverse processes
178
Sacral vertebrae
Sacrum
Spinal cord starts to gradually taper in this region
The sacrum forms a fibrosynovial joint between the sacrum and the wing of the ilium.
Sacroiliac joint
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Coccygeal vertebrae
Vertebrae that vary in shape and number
180
Ribs and sternum
Ribs:
Flat bone
Dorsally bone
Ventrally costal cartilage
-ribs 1-8 eternal ribs
-ribs 9-12 asternal or false ribs
-ribs 13 floating rib
Sternum:
8 sternebrae
Manubrium most cranial bone
Sternebrae 2-7 (short cylindrical bone)
8th sternebrae is longer and dorsoventrally flatted (xiphoid process)
181
What is the appendicular skeleton composed of?
-pectoral or forelimb
-pelvic or hindlimb
-shoulder and pelvic girdles
182
Clavicle
(Forelimb)
Clavicle = collarbone (frequently absent in dogs)
-cartilaginous in dogs (vestigial)
-ossified in cats
183
Scapular or shoulder blade
(Forelimb)
-prominent spine on the lateral surface (supraspinous fossa, Infraspinous fossa)
-distal end of the spine (acromion)
-the scapula narrows distally (neck)
-shallow articular socket (glenoid cavity, articulates with the humerus)
184
Humerus
(Forelimb)
-proximally large, rounded head (greater tubercle laterally, lesser tubercle medially)
-slightly twisted shaft
-distally it forms the elbow joint (medial epicondyles, lateral epicondyles, olecranon fossa and supratrochlear fossa which is only in dogs)
185
Radius and Ulna
(Forelimb)
Ulna:
-olecranon = point of elbow
-trochlea notch
-anconeal process
-lateral styloid process
Radius:
-rod shaped bone, shorter than the ulna
-medial styloid process
-fovea capitis - articulation with the humerus
186
Carpus
(Forelimb)
7 short bones, arranged in 2 rows
Proximal row: radial carpal bone, ulna carpal bone, accessory carpal bone
Distal row: articulates with the 4 metacarpal bones
187
Metacarpus
(Forelimb)
Dog and cats 1st metacarpal bone is smaller and non weight bearing (dew claw)
Metacarpal II-V articulate proximally with carpal bones and distally with phalanges
188
Digits or phalanges
(Forelimb)
Proximal phalanx (articulates with metacarpus)
Middle and distal phalanx distally forms ungual process
Small sesamoid bones = metacarpophalangeal joints and distal phalangeal joints
189
Pelvis
(Hindlimb)
2 hip bones - join and pubic symphysis
Each hip bone us made up of 3 bones = ilium, ischium, pubis
Its a sacroiliac joint
Acetabulum
Teres or round ligament
Obturator foramen (to reduce density, a channel for nerves and arteries, attachment for muscles/ligaments)
190
Femur
(Hindlimb)
-head of femur
-neck
-greater trochanter
-medial and lateral condyle
-trochlea groove
191
Tibia and fibula
(Hindlimb)
-Tibia expands proximally forming dorsal prominence (tibial crest, quadriceps femoris attaches)
-The distal tibia = medial malleolus
-fibula is a thinner bone lying laterally = lateral malleolus
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Tarsus
(Hindlimb)
7 short tarsal bones (arranged into 3 rows)
-talus and calcaneus
-talus articulates with the tibia
-Calcaneus articulates with the fibula (tuber calcis)
193
Metatarsus
(Hindlimb)
Anatomy similar to metacarpus and digits of the forelimb
Some animals have a small metatarsus I (hind dew claw)
194
Splanchnic Skeleton
(Hindlimb)
Develops within soft tissue
Not attached to the rest of the skeleton
(Os penis)
(Urethra runs within the urethral groove on the ventral surface of the bone in dogs)
195
Define tendon
Connects muscle to the bone
196
Define ligaments
Connects one bone to another bone
197
Structure of skeletal muscle
-Muscle is made up of individual muscle cells or fibres (myofibre)
-connective tissue surrounds the myofibres (endomysium)
-myofibres are grouped in bundles or fascicles (perimysium)
-connective tissue surrounds the groups of fascicles that make up the muscle (epimysium)
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Myofibres
The cell membrane is called the sarcolemma and the cytoplasm is called the sarcoplasm system of channels called the sarcoplasmic reticulum.
199
Structure of muscle fibre
Each myofibre is made up of myofibrils and each myofibril contains the sarcomere (the unit of contraction), contractile proteins (actin - thin filaments, myosin - thick filaments)
It is these 2 fibres that give the microscopic ‘striped’ appearance (striated muscle).
200
Slow skeletal muscles (type 1)
‘Slow twtich’
Have more mitochondria, capillaries (red) and myoglobin than their fast-twitch counterparts.
They can burn oxygen very efficiently aerobic, and are very useful for running or cycling for long distances.
201
Fast skeletal muscles (type 2)
‘Fast twitch;
Burn fuel anaerobically, eg without the use of oxygen in the process. These muscle fibres come in handy when generating speed in short bursts. Fast twitch muscle fibres are useful for running or cycling shorter distances at greater speed.
(Rich in capillaries - red)
202
Muscle contraction
A nervous impulse arrives at the neuromuscular junction which causes a release of a chemical called acetylcholine (Ach). Depolarisation of the motor end plate causes calcium (Ca+) to be released. In the presence of high Ca+ concentrations, myosin filaments can now attach to the actin, forming a cross-bridge
The breakdown of ATP releases energy which enables the myosin to pull the actin filaments inwards and so shortening the muscle. This repeated pulling of the actin over the myosin is often known as the rachet mechanism.
muscular contraction can last for as long as there is adequate ATP and Ca+ stores.
Once the impulse stops the Ca+ is pumped back and the actin returns to its resting position causing the muscle to lengthen and relax.
A single nerve fibre innervates a number of muscle fibres via a number of muscle fibres via a neuronal impulse (motor unit).
For accurate and delicate movements motor unit contains few muscle fibres.
For movement requiring less accuracy motor unit will be larger.
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Define isometric muscle contraction
Tone
The muscle does not shorten
Tone is maintained by a number of motor units contracting whilst others relax within a muscle belly.
The degree of tone in a muscle is controlled by the nervous system.
Increases when anxious/frightened
Reduces when relaxed and asleep.
It also allows the animal to maintain posture, muscles in a state of tension
204
Define isotonic muscle contraction
Muscle fibres all contact shortening the muscle.
This allows the actin and myosin filaments to move over each other, increasing the degree of overlap.
This is achieved by ‘bridges’ forming between the 2 filaments which are then ‘pulled’ shortening the sarcomere.
-ratchet mechanism shortening the muscle
-the cross bridges then reform and pull again, this process requires energy (ATP).
-relaxation, the cross bonds allow the myosin to move back
205
Define origin
(Muscles)
The starting point.
The muscle is attached to bone at 2 points. Moves least during contraction.
Proximal or medial tendon
206
Define insertion
(Muscle)
Opposite end to the origin. Where muscle inserts on the bone.
207
Define belly
(Muscle)
‘Classically’ shaped muscle.
Thick, fleshy central part
208
Define head
(Muscle)
Tapers at each end of the belly
Connective tissue muscle sheath is continuous with the dense fibrous connective tissue of the tendon that attaches the muscle to a bone.
209
Antagonistic pairing
(Muscle)
2 muscles that counteract each other
(Eg biceps, flexing and extending)
210
Aponeurosis
When muscles are presented in flat sheets the tendon is also drawn out into a flat sheet of connective tissue
(Eg the abdominal muscle)
211
Define sphincter muscle
Some muscles form a circular ring, controlling entry or exit to a structure
212
Extrinsic muscles
Muscles originating on the axial skeletal
Inserting on appendicular skeleton
Produce movement of whole limb
213
Intrinsic muscles
Originate and insert on one structure (such as the limb)
Cause movement within the limb
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What is a bursa?
Protective layer under the tendon.
It’s filled with synovial fluid over the point of the bone to reduce friction.
Connective tissue of a bursa may surround the tendon, allowing smooth movement over the the bone (synovial or tendon sheath)
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Masseter
(Muscles of mastication)
From dorsal skull
Inserts onto lateral mandible
Closes the jaw
216
Temporalis
(Muscles of mastication)
Over masseteric fossa on lateral mandible from zygomatic arch
Closes the jaw
217
Digastricus
(Muscles of mastication)
From caudovental mandible to jugular processes
Opens jaw with gravity
Moves jaw from side to side
218
Vertebral column
(Muscles of the trunk)
Expaxial muscles = dorsal to transverse processes of vertebrae
Hypaxial muscles = ventral to transverse processes of vertebrae
219
External and internal intercostals
(Thoracic muscles)
External = most superficial muscle, run caudo-ventrally, inspiration
Internal = next layer down to external, run cranio-ventrally, expiration
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Diaphragm
(Thoracic muscles)
Attaches to sternum, caudal rib and lumbar vertebrae.
Central tendinous area
Main muscle of inspiration
Innervated by phrenic nerve
Division of thoracic and abdominal cavities
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External abdominal oblique
(Abdominal wall muscles)
Broad, flat muscular sheets
provides abdominal wall strength = protection and support.
Most superficial
Runs in various directions
Originates; lateral surface of ribs and lumbar fascia.
Inserts; midline aponeurosis, linea alba.
222
Internal abdominal oblique
(Abdominal wall muscles)
Inserts on the linea alba
223
Transverse abdominis
Inserts onto the linea alba
224
Rectus abdominus
(Abdominal wall muscles)
Originates - 1st rib and sternum
Inserts - pubis, pre-pubic tendon
225
Linea alba
(Abdominal wall muscles)
Aponeurosis of the 3 lateral abdominal muscles
Runs from the xiphoid process to the pubic symphysis
226
Inguinal ring
(Abdominal wall muscles)
Aponeurosis of abdominal muscle at groin
Spermatic cord, vessels and nerves to the external genitalia
227
Trapezius
(Muscles of the forelimb)
Origin - mid cervical and thoracic vertebrae
Insertion - spine of scapula
Action - abductor of the forelimb and pulls the leg forwards (protraction)
228
Pectorals
(Muscles of the forelimb)
Origin - ribs and sternum
Insertion - humerus
Action - adducts the limb, keeping it close to the body wall
229
Latissumus dorsi
(Muscles of the forelimb)
Origin - thoracic vertebrae
Insertion - humerus
Action - flexes the shoulder and retracts the limb
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Brachiocephalicus
(Muscles of the forelimb)
Origin - based of skull
Insertion - cranial humerus
Action - limb on ground = bends the neck laterally. foot off ground = pulls leg forwards (protraction)
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Supraspinatus and infraspinatus
(Intrinsic muscles - attach and insert on forelimb)
Supraspinatus
origin = Supraspinatus fossa
Insertion = greater tubercle of humerus
Action = stabilises and extends the shoulder
Infraspinatus
Origin = infraspinatus fossa
Insertion = greater tubercle of humerus
Action = stabilises and flexes the shoulder
Both are known as an antagonistic pair.
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Intrinsic muscles of the elbow
Triceps brachii
Origins = 3 heads from the proximal humerus, 4th from the scapula
Insertion = olecranon of ulna (a bursa is also present)
Action - extends the elbow
Biceps brachii
Origin = supraglenoid tubercle of the scapula
Insertion = radius and ulna
Action = flexes the elbow
(Biceps tendon crosses shoulder joint)
Brachialis
Origin = humerus
Insertion = radius
Action = flexes the elbow
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Intrinsic muscles of carpus and digits
Carpal extensors
Origin = humerus
Insertion = carpus
(Cranial and lateral aspect of the limb)
Digital extensors
Origin = humerus
Insertion = 3rd phalanx
(Cranial aspect)
Carpal flexors
Run palmar to carpus
Digital flexors
Superficial digital flexor (inserts on 2nd phalanx)
Deep digital flexor (inserts on the 3rd phalanx)
234
Sub-lumbar hypaxial muscle
(Muscles of hindlimb)
Extrinsic
Ventral to vertebral column attaching to axial skeleton by the pelvis
Less extrinsic muscles compared to the forelimb
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Intrinsic muscles of thigh
(Muscles of hindlimb)
Group have common origin and insertion
Origin = pelvic girdle
Insertion = femur
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Gluteals (superficial, middle and deep)
(Muscles of the hindlimb)
Create ‘curve’ of rump
Action = extensors of hip
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Hamstring group
(Muscles of hindlimb)
Bicep femoris
Origin = pelvis
Insertion = calcaneus
Action = extends hip, flexes stifle and extends hock
Semitendinous
Origin = pelvis
Insertion = tibia and calcaneus
Action = extends hip, flexes stifle and extends hock
Semimembranous
Origin = pelvis
Insertion = femur and tibia
Action = extends hip and flexes stifle
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Quadriceps femoris
(Muscles of the hindlimb)
Largest muscle running down the cranial aspect of the thigh
4 parts to the muscle; 3 originating from the proximal femur, 1 originating from the ilium
Insertion = tibial tuberosity
(Tendon of insertion contains the patella)
Action = stifle extension
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Adductor muscles
(Muscles of the hindlimb)
Pectineus
Origin = pubis
Insertion = distal femur
Sartorius
Origin = pelvis
Insertion = cranial tibia
Gracillis
Makes up caudal medial thigh
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Intrinsic muscles of lower hindlimb
Gastrocnemius
Origin = caudal femur
Insertion = calcaneus
2 small sesamoid bones in tendon caudal to stifle
Action = extends hock, flexes stifle
Achilles tendon
Large, strong tendon running down caudal aspect of leg to point of hock.
Contains 3 tendons of insertion onto calcaneus
One tendon passes over hock - (Superficial digital flexor)
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Intrinsic muscles of hock and digits
Anterior tibialis
Origin = proximal tibia
Insertion = tarsus
Action = flexes hock and rotates paw medially
Digital extensors
Run down cranial aspect of limb
Digital flexors
Run down plantar aspect of limb
Superficial digital flexor attaches onto 2nd phalanx
Deep digital flexor attaches onto 3rd phalanx
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What are the 3 types of joints?
Fibrous
Cartilaginous
Synovial
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Fibrous joints
Joints occur where bones are held rigidly together by fibrous tissue.
Fibrous joints also classed as - synarthroses (a joint that permits little or no movement)
244
Examples of fibrous joints
Fibrous joints join the flat bones of the skull (sutures)
Syndesmoses (fastened with a band) between 2 areas of bone - radius and ulna
Gomphosis joints - the specialised fibrous joint that anchors the root of a tooth into its bony socket within the maxillary bone (upper jaw) or mandible bone (lower jaw)
245
Cartilaginous joint
The bones are connected by either fibrocartilage or hyaline cartilage and there is no space between the bones. They allow limited or no movement (amphiarthroses)
246
2 main types of cartilaginous joints
Synchondroses - bones are connected by hyaline cartilage. They are immovable (synarthrosis)
Eg - the joint between the diaphysis and epiphysis of a growing long bone in a growing animal.
Symphases - where the bones are united by a layer of fibrocartilage. They are slightly moveable (amphiarthrosis)
Eg - include the joints between vertebral bodies and the pubic mandibular symphysis
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Synovial joints
Aka diarthroses
Allow a wide range of movement
Joint surfaces (articular surfaces) covered in hyaline cartilage.
Bones are separated by a space filled with synovial fluid (aka joint cavity). The whole joint is surrounded by the joint capsule.
It has an outer fibrous layer (protection)
An inner layer known as the synovial membrane which secretes synovial fluid.
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Define articular cartilage
Protects the 2 bones
249
Define synovial membrane
Producers synovial fluid
250
Define joint capsule
Holds the joint together in a tough membrane
251
Name the stabilising ligaments found around/within synovial joints
Collateral Ligaments
Cruciate ligaments
252
What is menisci
Found within synovial joints.
Intra-articular discs of fibrocartilage act as shock absorbers within joint
Eg- stifle joint and jaw
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Synovial fluid
-viscous, straw coloured fluid
-varies in consistency (fitness and disease)
-lubricates joint surfaces
-provides nutrients for articular cartilage
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Define flexion and extension
Flexion - decreases angle between bones
Extension - increases angle between bones
255
Define abduction and abduction
Abduction - moves limb away from body
Adduction - moves limb towards midline of the body
256
Define Circumduction
The limb moves in a circle
257
Define rotation
The limb turns round on its long axis, like using a screw driver
258
Define gliding/sliding
When one articular surface slides over another
259
Define Pronation and supination
Pronation - Turing the lower surface of the paw downwards
Supination - rotation of the paw upwards
260
Define protraction and retraction
Protraction - moving the lib cranially, meaning it advances the limb forward (walking)
Retraction - moving the limb back towards the body
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What is scapular retraction and protraction ?
Retraction - moving the shoulder blades (scapula) towards the spine
Protraction - moving the shoulder blades away from the spine
262
Define hinge
Enable movement
similar to the opening and closing of a hinged door, but only in one plane (Flexion and extension)
(Elbow)
263
Define condylar
Where a convex surface fits onto a concave surface allowing Flexion and extension then over-extension
Allows movement in 2 planes; Flexion, extension and then over-extension (eg carpal joint, stifle)
264
Define pivot
This is where a bone sits inside another bone and allows rotation
Eg - atlantoaxial Joint
265
Define ball and socket (spheroidal)
Consist of the ball head of one bone fitting into the socket of an adjacent bone - most freely moveable joint.
Allows Flexion, extension, abduction, adduction, rotation and Circumduction
(Eg hip and shoulder)
266
Define plane/gliding
These occur between the surfaces of two flat bones allowing a small gliding action
Eg- small bones of carpus and tarsus
267
Define saddle
This joint allows 2 planes of movement, flexion/extension and abduction/adduction with a small amount of rotation
Eg - the site of articulation between the metacarpal bone and the thumb, phalanges
268
Structure of tendons
Strong bands of fibrous connective tissue linking muscle to bone.
Achilles tendon - large, strong tendon that runs down the back leg to the point of the hock. There is a bursa at the point of insertion on the hock
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Structure of ligaments
Thickened bands of fibrous connective tissue that connect bones and form the capsule of joints
270
Open fracture
Has a wound that has penetrated the skin and the fracture ends are open to the environment
271
Closed fracture
A fracture with no break in the skin
272
Define articular
Involving the joint
273
Define diaphyseal
Fracture in the midshaft or diaphysis of the bone
274
Define metaphyseal
Fracture of the area between the midshaft and the end of a long bone
275
Define physeal
Fracture through the growth plate on an immature animal
276
Define epiphyseal
A fracture in the epiphysis
277
Define condylar
A fracture of the epiphysis when condoles are involved
278
What is a condylar ?
A rounded protuberance at the end of a bone
-distal humerus or femur
279
Greenstick displacement
An incomplete fracture of a bone in an immature animal
280
Define fissure displacement
A fine crack, which may displace during surgery or when stressed
281
Define depressed displacement
Especially fractures of the skull, where fragments may be pushed into the underlying cavity
282
Define compression displacement
Often refers to fracture of the vertebral body where a compressive force has resulted in the shortening of a vertebra by a crushing effect
283
Define impacted displacement
Cortical fragments forced into cancellous bone
284
Define avulsion displacement
A fracture in which a bony prominence has been torn away from the rest of the bone, usually by the pull of a muscle
285
Direction of a fracture line: transverse
Fracture line is at 90 degrees to the axis of the bone
286
Direction of a fracture line: oblique
Fracture line is at an angle of at least 30 degrees
287
Direction of a fracture line: spiral
Fracture line curves around the bone
288
Direction of a fracture line: longitudinal
Fracture extends along the length of the bone
289
Define a simple fracture
One fracture line creating 2 fragments
290
Define a comminuted fracture
More than one fracture line, creating more than 2 fragments
291
Define a wedge fracture
A multi-fragmented fracture with some contact between the main fragments after reduction
292
Define a segmental fracture
One or more large complete fragments of the shaft of a long bone
293
Define an irregular fracture
A diaphyseal fracture with no specific pattern
294
Define multiple fracture
More than one fracture in the same or different bones
295
Salter-Harris system
Epiphyseal or growth plate fractures are classified by this system.
296
Define Luxation
(Dislocations)
A displacement of articular surfaces from the normal position within a joint
297
Define subluxation
Is a partial dislocation of the joint surfaces
298
Define congenital
Anatomical abnormalities present at birth which may or may not be inherited
299
Define acquired
Result from a trauma of some sort.
The ligaments keeping the joint in its normal position are damaged and the joint is forced out of alignment
300
What are the 8 functions of the skin?
1. Protection
2. Immunity
3. Sensory
4. Secretion
5. Production
6. Storage
7. Thermoregulation
8. Communication
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Skin function - protection
-Prevents loss of water and electrolytes from the internal environment
-Prevents absorption of toxic and harmful substances from the external environment
-Prevents entrance of pathogens
-Protects the body from mechanical trauma
-Presence of ‘flora’ on skin which complete abnormal bacteria
-Melanocytes produce skin and hair colouring (pigmentation) called melanin - protect against damage from UV radiation
-Sebaceous glands secrete sebum, spreads over skin surface and contributes to permeability of skin.
302
Skin function - immunity
Keeps out potentially pathogenic microorganisms.
Achieved by: constant shedding of the stratum corneum (has a lack of water, fatty acids and pH to provide a hostile environment to invaders)
Canine skin = 7.4pH feline = 6.4pH
pH is created via interaction between various acids (fatty, amino, lactic and carbon dioxide) and bicarbonate (an alkali) from sweat.
If bacteria gets past they must complete with resident microflora for nutrients. If that doesn’t work they are exposed to immunoglobulins.
303
Skin function - sensory
Monitor external environment
Achieved by sensory nerve receptors located in the lower part of the skin
4 basic stimuli = temp, pressure, pain, touch
Leading from receptors are nerve fibres which pass to the spinal cord.
304
Skin function - secretion
Produced by different glands in the skin and pass to surface.
-sebum by sebaceous sweat glands
-sweat by sweat gland
-milk by mammary gland
-pheromones by specialised skin glands
305
Skin function - production
Vit D required for absorption of calcium from the intestines - synthesised in skin by the action of UV light on a precursor chemical. UV light converts 7-dehydrocholesterol present in the sebum into vit D. This is activated in the kidney and liver and increases the uptake and metabolism of dietary calcium.
The Vit D produced is not metabolically active until it has undergone further chemical changes in the liver and kidneys. (Ergosterol conversion).
306
Skin function - storage
Fat is stored in lower layers of skin as adipose tissue. (S/c fat). Works as an energy store and a thermal layer. Amount varies by animal. Influencing factors = age, diet, physical fitness, environmental temp.
307
Skin function - thermoregulation
Primarily prevents heat loss:
Vasoconstriction = blood flow to skin is reduced to lower amount of heat energy which is lost from the skin
Coat provides insulation.
Piloerection = increased warmth. Controlled by arrector pili muscles.
S/c fat acts as insulation also.
Cutaneous regulation is less important in cats and dogs due to lack of arteriovenous shunts in the dermis.
Scrotum has thin tissue with little hair which keeps the testicles cool.
308
Skin function - communication
Pheromones = natural scents, produced by specialised skin glands, used for communication.
Eg anal glands, passed during defecation and marks territory.
Visual communication - threatened animal, erecting hair of coat (raising hackles) to appear larger.
309
Structure of skin
3 layers.
Epidermis = consists of keratinocytes, melanocytes, Langerhans cells, Merkels cells and lipids.
Dermis = contains collagen and elastin fibres, hair follicles, sweat glands, blood vessels, lymphatics and nerves
Subcutis (subcutaneous or hypodermis) = arranged into fat lobules divided by fibrous septae which serve to anchor the skin to the underlying muscles and transmit vascular, lymphatic and nervous structures
310
Epidermis
Most superficial layer - arises from the embryological ectoderm and is organised onto stratified squamous arrangement.
Layer is avascualr and devoid of nervous tissue.
Epidermis is further divided into other layers based on the degrees of differentiation of the keratinocyte, the main cell in the epidermis.
311
Stratum basale (epidermis)
Aka stratum germinativum
Contains germinative cells required for regeneration of the layers of the epidermis.
This layer is separated from the dermis by a thin basement membrane.
After mitosis the keratinocytes undergo maturation as they migrate to the surface (keratinisation)
312
Stratum spinosum
Epidermis
Spinous layer
Has a ‘shiny’ appearance of keratin filaments and desmosomes (cell-to-cell bridges) after histological straining.
Keratinocytes undergo structural and biochemical changes at this level. Cells at this time are still alive.
Has a spiky appearance
1-2 cells thick but up to 20 cells thick in a hairless area.
313
Stratum granulosum
Epidermis
Granular layer.
Cells in this layer contain keratohyalin granules - later involved with keratin organisation.
As keratohyalin accumulates it destabilises lysosomal membranes which release lysosomal enzymes causing cell death.
All cells in this layer are dead or dying.
They do not multiply and accumulate keratin from the stratum corneum
Alpha-keratin is soft and found in normal skin whereas beta-keratin is hard and found in claws and horns.
314
Stratum lucidium
Epidermis
Clear layer
The cells lose their nuclei and become clearer
315
Stratum corneum
Epidermis
(Horny layer)
The cells do not have a nucleus, are flattened and being constantly shed into the environment.
Held together via different lipids (sphingolipids, ceramides, cholesterol, free fatty acids).
316
What is the cell renewal time?
(CRT)
Time it takes for a cell to migrate from the stratum basale to the stratum granulosum (22 days approx - normal canine skin)
The CRT is influenced by factors which may delay or increase this time:
-glucocorticoids (both exogenous and endogenous)
-UV light
-Arachidonic acids and associated metabolic factors
-epidermal growth factor
-epidermal chalone
317
Acronym for epidermis skin layer
Brave - basale
Shepherds - spinosum
Guard - granulosum
Lambs - lucidum
Carefully - corneum
318
Melanocytes
Originate from neural crest cells and migrate to the stratum basale of the skin, retina and mucous membranes during embryogenesis.
Each melanocyte connects to 25-30 keratinocytes and produces various types of melanin which are required for protection against Uv rays and free radical scavenging.
Melanocytes produce melanin, which then passes onto neighbouring keratinocytes.
Melanocytes do not undergo mitosis but can mutate into cancerous melanomas.
319
Dermis
The connective tissue layer.
Contains blood vessels, lymph vessels, nerves, receptors and sensory structures.
Important in thermoregulation
Where skin sutures are anchored when closing a wound.
Each hair follicle has an arrrector pili muscle - responsible for hair standing on end and a sebaceous gland within dermis, however they originate from the epidermis cells.
320
Hypodermis/subcuticular layer
Directly below skin
Made up of - loose connective tissue, fat cells and elastic fibres.
321
Nerves
(Skin)
Required for - sensory perception, control of vasomotor tone to the blood vessels, piloerection and nervous control to the secretory glands.
Several types of mechanoreceptors found in the skin:
-Pacinian corpsudes = vibration and pressure
-Meissner’s/Ruffini eopuscles = velocity of skin, movement/touch
-Hair movement sensors
-Slow adapting type = Merkel cells - activated by steady pressure and tactile stimuli
-Slow adapting type 2 = activated by skin stretch
-high threshold - mechanoreceptors respond to painful stimuli
-polymodal nociceptors - transmission occurs via unmyelinated (slow conducting) C-axons and produce a diffuse burning itching sensation.
322
What are the 3 vascular systems that supply blood to the skin?
The superficial plexus = right below the epidermis and supplies this layer and the upper portions of the hair follicles.
The middle plexus = located at the level of the sebaceous glands. Sends branches to supply the superficial plexus, the sebaceous glands and the remainder of the hair follicle.
The deep plexus = found at the boundary between the dermis and subcutis. Supplies the middle plexus, the apocrine sweat glands, hair follicle and subcuticular tissue.
323
The nose/rhinarium
(Skin)
-hairless
-keratinised
-heavily pigmented (in most individuals)
-epithelium contains no stratum lucidium
-contains numerous sweat glands
-epithelium on nose acts as finger print
324
Footpads
(Skin)
-stratum corneum is thickened and heavily keratinised
-pigmented and hairless
-provides increased protection against abrasion
-in dogs the epidermis is covered in conical papillae giving it the rough appearance (cats are smooth)
-dermis is thickened, very vascular and contains adipose tissue, forms a digital cushion that supports foot and provides some shock absorption as feet hit the ground.
-sweat glands that open onto surface
325
Paw pads
(Skin)
Digital pads = protects distal interphalangeal joint, one at the dew claw.
Metacarpal/metatarsal pad = protects phalangeal/metacarpal/tarsal joint. Heart shaped in dogs, round in cats.
Carpal pad/stopper pad = just distal to the carpal bones and protects when running at high speeds.
326
Claws
(Skin)
Is modified epidermis and grows from a specialised part called the coronary boarder or coronary band, this lies underneath a fold of skin, the claw fold.
The claw grows in 2 sheets which forms the walls of the claw and cover the undulating process of the third phalanx.
The sole in the groove between the two walls is made of softer horn. The dermis lies between the horn and the third phalanx and provides the blood and nerve supply to the claw.
327
What are claws used for ?
-protection
-grip
-manipulation of food
-predatory
-scent marking
-grooming
328
Difference between dogs and cats claws.
Dogs = tubular in shape, strong and rarely shed, not able to retract, not as sharp, generally pigmented
Cats = laterally flattened, easily shed, brittle, can retract when not using them, sharper, used as defensive weapon, less pigmented
329
Skin glands
Sebaceous glands = simple alveolar holocrine gland. Opens into a hair follicle halfway up the shaft. The sebum produced by these glands spreads over the surface of the skin and provides animals with a glossy coat.
Sebum is an oil based compound.
Functions to prevent skin desiccation and is important in deterring pathogenic bacteria.
With cells that compromise the sebum disintegrate, the lipids in the cells break down and form hydrocarbon chains which from the scent signature which is specific to each dog.
Dehydrocholesterol, a precursor to Vitamin D is present in sebum, when irradiated by UV light, converts to the active form of Vitamin D which is then absorbed through the skin.
Pheromones are produced and excreted here.
Number of glands increase where less hair.
330
Where are the specialised sebaceous glands located?
Tail glands = dorsal aspect of tail.
Circum anal glands = form a ring around anus, this is what dogs smell when they sniff each other
Anal sacs = sit at 4 and 8 o clock. Contains pheromones - expressed during defecation, marking territory
Circumoral glands = lips of cats. Secrete pheromones and are for communication. Used to mark territory.
Ceruminous = found in external ear canal and secrete ear wax.
Meibomian = found in the mucocutaneous junction of the eye and secrete fatty component of tears
331
Sudoriferous glands
(Skin)
Sweat glands = simple coiled tubular structures which arises in 2 forms, eccrine (watery secretion) and apocrine (oilier product)
Apocrine = glands are located throughout the haired skin of dogs and cats. Below sebaceous glands and open into primary hair follicles. Sweat from these glands are important in providing IgA and other antimicrobial products to the skin surface along with pheromonal properties. (Associated with hair follicles)
Eccrine = found only in footpads of dogs and cats. Located deep in dermis and subcutis. Glands do not open into hairs but directly onto footpad surface. Releases a hypertonic (alkaline product). Surrounded by myoepithelial cells which contract to squeeze out moisture. (Without hair follicles)
332
Mammary glands
(Skin)
-modified sweat glands
-5 pairs in bitches , 4 pairs in queens
-develop in the embryo from mammary ridges that run from the axilla to the groin, a teat papilla develops on the surface of the body, then solid epidermal buds or sprouts grow downwards into the hypodermis and branch. When the branching system has been well established the epidermal tissue hollows to produce the duct system of the gland.
Rudimentary teats are found in males.
Consists of glandular tissue surrounded by fibrous connective tissue and fat.
Becomes active and hypertrophied in pregnancy and stats to produce secretions.
The teats hypertrophy also so they stand out to pups/kits
Milk = source of nutrients for new Borns. First milk is colostrum containing antibodies.
333
Hairs
(Skin)
-composed of keratin plus pigments
-formed from the epidermis that firstly extends into dermal tissue to form a ‘hair cone’ over a piece of dermis called the dermal hair or hair papilla.
As hair starts to grow from cone the epidermal cells around it are destroyed, leaving an open channel or hair follicle for the hair.
Hair grows continuously until it dies and becomes detached from cone. Will either shed or stay attached to body until combed out as it’s supported by other hairs
334
What are the 3 types of hair?
-guard/primary
-wool/secondary/undercoat
-vibrissae/tactile
335
Role of guard hairs
Aka primary or ‘top coat’
Outer protective coat
Thick long and stiff
Lies close to skin - giving smooth appearance
Provides a degree of waterproofing
1 guard hair from each primary follicle
Can be raised by the smooth arrector pili muscle in thermoregulation and communication
336
Role of undercoat hairs
Aka languo
Thinner, shorter, softer and present in higher numbers
Form dense insulating layer
Thickness varies between breeds - but usually thicker in winter months
-wool hairs grow from secondary follicles - each producing a number
337
Role of vibrissae hairs
Aka tactile or whiskers
Thicker than guard hairs
Follicles deep within hypodermis
Follicle surrounded by sensory nerve endings so any movement detected
Only found: upper lip, eyelashes, eyebrows, cheeks, chin, carpus of the cat
338
Structure and formation of hair
-outer cuticle
-a cortex, often pigmented
-inner medulla
-root or bulb of the hair
The hair shaft is above skin surface whereas the hair root is within follicle.
Formation:
-‘peg’ of epidermal cells grows down into dermis forming a cone
-underlying dermal papilla supplies blood supply and nerves to growing hair
-from the hair cone, the cells keratinise and form a hair
-grows up through epidermis to skin surface
-at this point the cells of the cone die, forming a channel - the hair follicle
-hair continues to grow and then becomes detached from follicle
339
Growth cycle of hair
Anagen phase = growth
Catagen phase = transition
Telogen phase = resting
Exogen= fallout
340
Hair growth
Hair growth is influenced by photoperiod and nutrition
65-90% of hair made up of protein
Coat quality can be used to assess nutrition
341
Define active vomiting
Preceded by salivation and nausea, followed by strong abdominal contractions and expulsion of vomit
342
Define passive vomiting
‘Regurgitation’
Often overflow of oesophageal contents
343
Define projectile vomiting
Violent ejections of the stomach contents which is characteristic of pyloric stenosis.
344
Saprophytes (digestion)
Feed on dead or decaying material. Secrete digestive enzymes onto food externally.
345
Parasites (digestion)
Feed on living organisms (their host)
Beneficial to the parasite but harmful to host.
346
Holozoic feeders (digestion)
Take food into their bodies and digest it.
Either carnivore, herbivore or omnivore
347
Define ingestion (digestion)
Taking food into the body
348
Define peristalsis (digestion)
Propelling food along the digestive system by muscular contractions of the gut wall
349
Define digestion
Breakdown of large insoluble food molecules into simple soluble molecules.
Can be mechanical or chemical
350
Define absorption (digestion)
Passage of digested food thought the gut wall into the blood stream
351
Define egestion
Elimination of indigestible food from the body
352
What digestive system do carnivores and omnivores have?
Monogastric digestive system
353
What are the functions of the digestive system ?
-ingestion
-digestion
-absorption and metabolism
-excretion
354
What are the parts of the digestive system
-mouth
-pharynx
-oesophagus
-stomach
-small intestine
-large intestine
-anus
355
What accessory glands contribute to the digestive system.
-salivary glands
-pancreas
-liver
-gall bladder
356
What are the 4 types of teeth ?
Incisors (used for cutting)
Canines (fangs, eye teeth, tusks - are tearing teeth)
Premolars
Molars (grind the food) largest teeth is the carnassial
357
Canine dental formula
Deciduous = I3/3 C1/1 pm3/3 X2 = 28 teeth
Eruption times = I 3-4 weeks C 5 weeks Pm 4-8 weeks
Permanent = I3/3 C1/1 pm4/4 M2/3 X2 42 teeth
Eruption times = I 3.5-4 months C5-6 months pm 1st premolar 4-5 months remainder 5-7 months M5-7 months
358
Feline dental formula
Deciduous = I3/3 C1/1 pm3/2 X2 = 26 teeth
Eruption times = entire dentition starts to erupt at 2 weeks and is complete by 4 weeks
Permanent = I3/3 C1/1 Pm3/2 m1/1 X2 30 teeth
Eruption times = I 12 weeks Pm variable - full dentition present by 6 months
359
Rabbit dental formula
I2/1 C0/0 pm3/2 m3/3 X2 = 28 teeth
360
Tooth anatomy
-tooth consists of a crown that projects above the gum, a neck surrounded by gum, and one or more roots embedded in sockets in the jaw.
-crown is covered in a layer of enamel which is the hardest substance in the body.
-enamel consists mainly of calcium, phosphate and fluoride.
-rest of tooth is composed of dentin - similar composition to bone
-a pulp cavity in the centre of the tooth is filled with pulp (connective tissue containing blood vessels and nerves).
-a layer of bonelike cement covers much of the root and holds the tooth firmly in the jaw.
361
Function of the mouth
Prehension - to pick up food (lips and tongue)
Mastication - breaking up food for swallowing (into smaller boluses)
Lubrication - with mucous and saliva (to aid swallowing)
In omnivores/herbivores digestion of carbohydrates starts at the mouth (NOT in carnivores)
362
Salivary glands
(Digestion)
-4 pairs of salivary glands (zygomatic, parotid, sublingual, mandibular)
-ducts open into oral cavity, pour saliva onto food as its chewed in mouth
-produced continuously but increases with anticipation of food
-salivation occurs through: fear, pain, anticipation of vomiting, an irritant (chemicals and gases)
-clear liquid (99% water 1% mucus)
363
Hard palate
-Formed by palatine processes of the incisive, maxillary and palatine bones.
-covered by mucosae which is raised into transverse ridges (rugae) which aid in transportation of food towards back of mouth.
364
Soft palate
-Merges off the hard palate
-lined with the same epithelium as hard palate but comprises soft tissue instead of bone.
-covered with respiratory epithelium on its dorsal surface and oral mucosa Ventrally.
-has salivary glands within mucosa
-divides pharynx into nasopharynx and oropharynx.
-muscle is present - needed when animal swallows. can be lifted to block trachea
-required for breathing and swallowing
365
Pharynx
-forms a cross over between digestive and respiratory systems
-walls are muscular and lined with mucous membrane that is continuous with the lining of the oral cavity and of the oesophagus.
-has lymphoid tissue : tonsils
-connected to middle ear by Eustachian tube (equalises air pressure around tympanic membrane)
366
Oesophagus
-simple muscular tube that connects pharynx to the cardiac sphincter of the stomach.
-4 layered structure, seen throughout gastrointestinal tract
-expands widthways, the flexibility is very important in carnivores due to eating prey in large chunks.
-well supplied with nerves and blood vessels
367
Prehension and mastication
Prehension - lips, teeth and tongue used for picking up food and taking it into mouth. Action varies with species
Mastication - teeth are used to chew food into smaller pieces. Lips and tongue roll food around and combine it into a bolus or a lump of food. Saliva helps to soften and stick the pieces together for swallowing.
368
Deglutition
When bolus is ready to be swallowed it is pushed to back of tongue. The soft palate prevents the food going into nasal passages ans the epiglottis closes over the larynx. This prevents food entering the trachea and passing into lungs.
A wave of muscular contractions known as peristalsis passes down the pharynx causing bolus to be directed into the oesophagus, food travels from oesophagus to stomach by peristalsis.
On average this takes 15-30 secs. Liquids being faster than dry foods.
369
Stomach (digestion)
-process of digestion begins
-sac like structure lying in the cranial abdomen.
Functions:
-act as a reservoir for food before it digested into small intestine
-mix and break up food
-to begin the process of protein digestion
-secretes gastrin (hormone) into blood
370
Stomach contractions
-stomach has 3 layers of smooth muscles, this is responsible for causing muscle contractions
-muscle contractions mix the stomach contents and push them into duodenum
-lining of stomach has deep longitudinal folds called rugae which flatten as the stomach fills with food.
2 types of stomach contractions:
Rhythmic segmentation and peristalsis = movements become more frequent when the stomach is empty and contribute to sound of stomach rumbling.
Reverse peristalsis = occurs during vomiting. Food is propelled in the opposite direction. Cardia opens and food passes into oesophagus and out into the mouth.
371
Gastric secretions
-mucosal lining of stomach is simple columnar epithelium with numerous tubular gastric glands. The gastric glands open to the surface of the mucosa through tiny holes called gastric pits.
3 different types of gastric cells make up gastric glands:
-mucous and goblet cells = found in all parts of stomach. Secrete mucous to lubricate the food and protect stomach wall from damage from digestive enzymes.
-parietal cells = found within the Fundus, secrets HCL, creates an acid pH which enables pepsin to work effectively.
-chief cells = found within the Fundus, secrete pepsinogen, the precursor to the active enzyme pepsin. Pepsin breaks down proteins to peptides.
372
Endocrine cells
D cells = found in the stomach (pylorus), intestine and pancreatic islets. Secrete somatostatins - released when the stomach reaches a certain level of acidity.
G cells = sit in stomachs pylorus region. Produce the hormone gastrin. Gastrin can increase HCL production by stimulating ECL like cells to release histamine. (Enhances)
Enterochromaffin-like cells = control acid secretion by releasing histamine as a paracrine stimulant.
Located near the basement membranes in the gastric oxyntic region.
These products are secreted directly into the bloodstream.
Endocrine cells secrete the hormone gastrin - functions the regulation of gastric activity.
373
Small intestine
-most important in enzymatic digestion
-absorption of the products for digestion
-in most mammals its 3 and a half times its body length (roughly 6m in a dog)
-chemical digestion with intestinal juice, pancreatic secretions and bile.
-Pancreas releases pancreatic juice containing digestive enzymes into the duodenum.
-liver produces bile which is stored in the gall bladder and secreted into the duodenum through bile duct.
374
Small intestine has 3 areas called :
-duodenum
-Jejunum
-ileum
375
What is the structure of the small intestine?
4 layers:
The mucosa - simple columnar epithelium with intestinal glands forming vili
The submucosa
The smooth muscle
The serosa (outer layer)
376
Duodenum (first part of small intestine)
(Chyme)
Partially digested food does from stomach through pyloric sphincter into duodenum.
Duodenum contains intrinsic glands (within the wall of intestine) known as Brunners glands - they secrete a mixture of digestive enzymes known as succus entericus.
Duodenum takes the form of a U-shaped loop with the pancreas lying within it.
377
Jejunum and ileum (small intestine)
Contains intrinsic glands known as crypts of Lieberkuhn
Referred to as intrinsic glands as they are within the wall of the intestine
Secrete a mixture of digestive enzymes
Both narrow mobile tubes in no fixed position
378
Large intestine contents of a dog:
-caecum
-ascending colon
-transverse colon
-descending colon
-rectum
-anus
379
What is the main function of the large intestines ?
1. Absorb water
2. Vitamins
3. Electrolytes
380
Caecum
Short blind ending sac
Has no significant function in dogs and cats
Well developed in rabbits and guinea pigs as it contains bacteria which breaks down cellulose
381
Large intestine
Initial part = ascending colon - on right side of animal.
Transverse section and descending colon found on the left side of the abdomen.
Transverse section travels from R side of abdomen between the stomach and intestines.
Descending is the longest segment travelling down the L side until it reaches the pelvic cavity where it continues to rectum.
Rectum lies midline in the pelvis and is situated dorsally above the urinary and reproductive organs.
Passage of food from ileum to the large intestines is controlled by the ileo-caecal valve.
Many goblet cells secreting mucin as lubrication for moving material.
382
Anal canal
Joints at the last part of digestive tract to the outside world.
Short and contains 2 sphincters.
Internal sphincter = thickening of smooth muscle of the gut.
Outside sphincter = striated muscle
The area of skin around the anus under the tail is called the perineum or perineal area.
383
Anal glands
Scent glands.
2 anal sacs located at 4 and 8 o’clock.
The sacs have a lining producing a fluid which contains pheromones and is responsible for territory marking.
A duct from each sac empties into the anus in the dog and just outside the anus in a cat.
These glands should empty when the animal defecates.
Problems can arise when emptying doesn’t occur when defecating, causing clinal signs (anal irritation)
384
Faeces formation
Water, vitamins and electrolytes are absorbed in the large intestine (colon).
Bacteria assist in the breakdown of any organic material in food and they contribute to smell of faeces.
Absorption of water ensures the body does not lose excessive water and that the faeces are firm and formed.
385
Normal faces contents
-water and fibre
-dead and living bacteria
-dead intestinal cells
-mucus
-contents of the anal glands
-stercobilin - a pigment derived from bile which gives faeces its colour.
386
Liver
Located on the right side in the cranial abdomen directly behind the diaphragm immediately in front of the stomach and is the largest gland in the body.
Reddish/brown colour and is firm in consistency.
Attached to the ventral abdomen by the falciform ligament.
Liver is divided into lobes by large fissures. Functional units of the liver are lobules with sinusoids that carry blood from the hepatic portal vein.
Responsible for: production of heat by way of the many chemical reactions taking place in its tissue, production of bile, red blood cell production, area where products of digestion are metabolised.
It is able to regenerate itself if damaged and is essential for life.
387
Blood supply of the liver
3 way.
Liver receives blood from 2 sources.
Hepatic artery = freshly oxygenated blood is bought to the liver.
Hepatic portal vein = blood that is rich in nutrients from the digestive tract is carried to the liver.
Hepatic vein = takes blood away.
388
Bile
Produced in the liver and stored in the gall bladder until needed for digestion.
Enters the duodenum via the bile duct which is attached to the liver.
Contraction of the wall of the gall bladder forces bile out into the intestine.
Bile is essential for the breakdown of fats.
If too little bile is produced you will see fat in the faeces.
Bile does not enter the intestines until the food is present and is green/yellow in colour
389
Liver functions
Produces bile - stored in gall bladder
Regulates amino acids
Stores glucose as glycogen
Stores fat and fat soluble vitamins
Produces all clotting factors
Produces albumin and globulin
Detoxifies dangerous waste products, excretes these in bile
Destroys old red blood cells, excreted in bile
Stores iron as haemosiderin
390
What does the liver produce/synthesise ?
-glycogen
-cholesterol
-plasma proteins
-bile salts (sodium glycocholate, sodium tautocholate)
-bile pigments (bilirubin, biliverdin)
-bicarbonate
-haemosiderin
-urea
-erythropoietic factor (substance that stimulates bone marrow to make red blood cells)
-detoxification
-breaks down many drugs
391
Gall bladder
Lies between the Quadrate and right medial lobes and is a pear shaped sac thats attached to the visceral surface of the liver by cystic duct.
Principal function = storage reservoir for bile.
Bile contains water, bile salts, bile pigments and cholesterol.
When chyme enters a release of CCK and secretin enables the wall of the gall bladder contract and expel bile unto the digestive tract.
392
Pancreas
Has both endocrine and exocrine functions.
Endocrine portion consists of scattered islets of Langherhans which secrete the hormones insulin and glucagon into the blood.
Exocrine portion is a major part of the gland. Consist of pancreatic acinar cells that secrete digestive enzymes into tiny ducts interwoven between the cells. These act upon carbohydrates, fats and proteins.
Secretions are controlled by hormone secretin and cholecystokinin.
The enzymes enter the duodenum via the pancreatic duct that joins the common bile duct.
393
Enzymes
Amylase - continues breakdown of starch
Lipase - breaks down lipids to fatty acids and glycerol
Trypsinogen - which is converted to active trypsin by the intestinal enzyme enterokinase
Trypsin - Acts on proteins and the products of protein breakdown started by the pepsin in the stomach
Chymotryopsinogen - inactive form is converted to active chymotrypsin by trypsin, breaks down some parts of peptides to amino acids.
Carboxypeptidose - breaks down some parts of peptides to amino acids.
The pancreas also makes bicarbonate ion to neutralise the HCL from the stomach which facilitates these enzymes which would be denatured by stomach pH.
394
Process of absorption
Pyloric sphincter = a gateway separating the stomach and the small intestine, controlling the entry of chyme.
Chyme = a slushy acidic mixture of food and digestive juices.
Enzymes = protein molecules that increase the speed of chemical reactions in the body.
Villi - projections along the small intestinal wall. Increasing surface area for greater absorption.
Hydrolysis - splitting of substances by adding water
Glycerol - combination of fats and oils.
395
Nutrients (digestion)
Water = most important. Makes up 60-70% of fat free body weight.
Carbohydrates = broken down into simple sugars (saccharides) and fibre
starch = simple sugars = digestible
Fibre = bulk = non digestible
Protein = made out of 20 different amino acids. Some are essential (taurine in cats)
Fat = energy source. Carry the fat soluble vitamins A, D, E and K. Unsaturated fat carries essential fatty acids.
Minerals = can be macro minerals if needed in relatively large quantities (calcium or phosphorus) or micro minerals if needed in very small quantities (copper, magnesium). Each mineral has its own role.
Vitamins = small quantities required to perform metabolic functions.
Water soluble = B and C
Fat soluble = A, D, E and K
396
Nutrient absorption
Villi contain a loop of blood capillaries that lead to the hepatic portal vein and lymphatic capillary called a lacteal.
Amino acids and sugars = villi, hepatic portal vein, liver, cells
Fatty acids and glycerol = pass into lacteal as chyle, travels along lymphatic system to heart, enters blood for storage or use.
397
Why do multi-cellular organisms require a more specialised transport system?
-in larger organisms diffusion is too slow
-because organisms surface area to volume ratio
-single celled organisms have a very large surface area to volume ratio, so the diffusion path is short.
398
What 3 components do all circulatory systems have?
-circulatory fluid (blood)
-pipework (artery, vein, capillaries)
-pump (heart)
399
What are the functions of blood?
Transport = of oxygen, nutrients, hormones, enzymes, metabolic waste (carbon dioxide, nitrogenous wastes)
Protection = white blood cells, antibodies, complement proteins, clotting mechanisms
Regulation = of body temp, fluid and pH (acid-base)
400
Define haemopoiesis/haematopoiesis
Process that produces the formed elements of the blood from stem cells originating in the bone marrow.
Haemopoietic tissue: jelly-like connective tissue in the bone marrow of long bones
401
Define erythropoiesis
Red blood cells
402
Define leucopoiesis
White blood cells
403
Define thrombopoiesis
Platelets
404
What pH is blood?
7.4
405
Functions of blood
Transport oxygen, nutrients, waste and carbon dioxide
Regulation
Protection
406
What is blood made of?
Plasma = 55%
White blood cells and platelets = <1%
Red blood cells = 45%
407
Plasma
Pale straw coloured liquid
Made mostly of water and carries:
Red and white blood cells
Platelets
Nutrients (glucose and amino acids)
Clotting factors
Mineral salts (sodium, chlorine, potassium, calcium, magnesium)
Waste like urea and carbon dioxide
Hormones and antibodies
Plasma proteins
-when plasma uses clotting factors it becomes serum
408
Red blood cells
Erythrocytes
Transports oxygen and carbon dioxide
Biconcave circular discs
7um in diameter
Contain the protein haemoglobin
Anuclear
Large surface area: volume ratio
Oxygen diffuses through the membrane combining with haemoglobin to form oxyhaemoglobin
1mm cubed contains over 5 million red blood cells
Life span = 120 days
409
White blood cells
Leukocytes
Smaller numbers than RBC
Nucleated cells
Defence against infection
410
Granulocytes
Produced by the bone marrow
70% leukocytes
Granules in cytoplasm
Segmented or lobed nuclei
Sometimes called polymorphonucleocytes
(PMN) - many shaped nuclei
Classified according to type of stain they take up
411
Neutrophil (granulocyte)
Stains purple
Engulf bacteria and debris
Life span is short (1-4 days)
Segmented nucleus
Neutrophilia = increased amount
Neutropenia = deficient
412
Eosinophil (granulocyte)
Stains red
Nucleus often has 2 lobes
Regulate allergic and inflammatory processes
Play an important role in the management of parasitic infections
Eosinophilia = increased amount
413
Basophil (granulocyte)
Stain blue
Nucleus with separated lobes
Basophils secrete histamine and heparin
414
Agranulocytes
Cytoplasm is clear
Life span of several months
Two cells in this group
415
Lymphocytes (agranulocytes)
80% agranulocytes
Main cell of immune system
Produced in lymphoid tissue
Larger than RBC
Relatively large, dense, round nucleus
Blue staining cytoplasm
Life span varies = few days to years
Important cells in specific immune response
416
Monocytes (agranulocytes)
Largest leucocyte
Oval, or horse shoe shaped nucleus
Blue staining cytoplasm
Produced by bone marrow
Only present in small numbers
417
Thrombocytes
Platelets
Cell fragments formed in bone marrow
Small anuclear discs, present in large numbers in blood
2-4um in diameter
Often seen in ‘clumps’
Life span = 10 days
Role in clotting mechanism
418
Packed cell volume (PCV)
Measurement of red blood cells present in the blood.
A sample is put in a capillary tube, one end is sealed and it is spun in the centrifuge to separate the heavy blood cells from the plasma.
Calculation formula:
PCV% = length of column of RBC divided by total length of column X 100
419
Normal PCV values of cat and dog ?
Cat = 35%
Dog = 45%
420
What does increased PCV mean?
Dehydration or an abnormal increase in RBC production
421
What does decreased PCV mean?
RBC loss from any variety of reasons like cell destruction, blood loss and failure of bone marrow production.
422
Blood clotting - why is it essential?
-essential to wound healing
-damaged blood vessels can be sealed
-blood loss can be minimised
-it prevents to entry of pathogenic microorganisms
423
What happens if a blood vessel is damaged ?
1. Platelets stick to the damaged vessel wall, forming a seal (exposed collagen fibres). Platelets release the enzyme thromboplastin (prothrombin activator)
2. In the presence of thromboplastin and calcium ions, the plasma protein prothrombin is converted into thrombin (an active enzyme).
3. Thrombin then converts the plasma protein fibrinogen into a meshwork of insoluble fibres called fibrin. Fibrin forms a network across the deficit, trapping blood cells, forming a clot.
424
What can affect clotting times?
Reduced by: surface contact with materials that will act as foundation for clotting (gauze, swabs)
Raising environmental temperature (keeping an animal in a warm kennel)
Increased by: lack of vitamin K, liver disease, genetic factors, systemic disease, thrombocytopenia, lack of blood calcium, parasitic disease
425
Fish heart
2 chambered
The less muscular atrium receives blood from the body.
A muscular ventricle which pumps blood to the gills.
Blood leaves the gills via the aorta
426
Amphibian and most reptiles heart
Three chambered heart
2 atria and one ventricle - mixing of oxygenated and deoxygenated blood is kept to a minimum due to the timing of the contractions between the atria, this is called an incomplete double circulatory system.
Could also absorb oxygen through their skin when moist.
427
Birds and mammals heart
4 chambered heat
Fully separated pulmonary and systemic circulations
428
Location of the heart
Lies between right and left lungs in the thoracic cavity.
Protected by the sternum Ventrally and thoracic vertebrae dorsally.
Lies slightly to the left and is well protected by the rib cage and sternum.
429
Structure of the heart
Consists of 2 pumps fused together - each has 2 chambers (atrium and ventricle)
Valves to prevent back flow
Cone-shaped
Base - located dorsal and cranial in the thorax
Apex - ventral and caudal
Heart wall consists of - endocardium, myocardium, epicardium, pericardium.
Mainly consists of cardiac muscle tissue. Made up of cells that enables electrical impulses to pass through the tissue. Contains large numbers of mitochondria and myoglobin molecules.
Heart is enclosed in a sac (the pericardium), this is a potential space containing a small quantity of fluid for lubrication of the outer surface of the heart.
430
Define pericarditis
Inflammation of the pericardium
431
Define tamponade
Blood or fluid collects in the pericardium, the sac surrounding the heart. This prevents the heart ventricles from expanding fully
432
How does the heart work
Stage 1 - diastole = atria and ventricles relax
Stage 2 - atrial systole - atria contracts and ventricles relax, valves open to allow blood into the ventricles.
Stage 3 - ventricular systole = atria relaxes, ventricles contract. Valves close to stop blood flowing backwards, ventricles contract forcing blood to leave the heart, at the same time the atria are relaxing and once again filling with blood.
Cycle repeats
433
Electrical activity in the heart
Beat starts at sinoatrial node (pacemaker)
Specialised area of cardiac muscle within right atrium wall
Autonomic nerves control the rate
Impulse to contract starts at the node and spreads across atria, wave reaches atrioventricular node.
When the AV node is excited it sends impulses along a specialised bundle of fibres called the ‘bundle of His’ which runs down intraventricular septum
Impulses passes down fibres running along the interventricular septum
At bottom of ventricles bundles of his split into left and right branches (these spread into 2 ventricles)
Contraction status at apex and moves up
Forcing blood up and towards the aorta and pulmonary artery.
434
ECG
Measures electrical activity in the heart.
PQRST
P wave = depolarisation of the aorta
QRS complex = depolarisation of the ventricles
T wave = recovery wave
435
Sinus rhythm
Occurs when the sinus node depolarises spontaneously and the consequent wave of depolarisation follows the natural pathways through the heart.
436
Ventricular fibrillation
A rapid and disorganised rhythm of heartbeats that rapidly leads to loss of consciousness and sudden death if not treated immediately.
437
Heart sounds
Produced by the closing of valves
Normal sounds are produced when valves snap closed: LUB-DUB
LUB = closing of AV valves - beginning of systole
DUB = closing of semilunar valves - end of systole
438
Abnormal valve sounds
Leakage of valve = swishing sound (murmur)
Narrowing of valve = stenosis = high pitched sound
439
What are the 3 types of blood vessels?
-artery
-vein
-capillaries
440
What way do arteries carry blood?
Away from the heart
441
What way do veins carry blood?
Towards the heart
(Exception - portal veins)
442
What are the 3 layers of tissue in both arteries and veins?
1.tunica intima
2.tunica media
3.tunica externa (or adventitia)
Capillaries are made up of a single layer of endothelial cells
443
Tunica externa
Strong outer covering
Composed of connective tissue, collagen and elastic fibres.
Fibres allow arteries and veins to stretch - preventing overexpansion
444
Tunica media
Middle layer of the walls of arteries and veins
Composed of smooth muscle and elastic fibres
445
Tunica intima
Inner layer of arteries and veins
446
Arteries
Carry blood away from the heart.
Thick, elastic walled vessels (elastic fibres and smooth muscle)- adapted for withstanding the high pressure that is exerted from the heart.
Lumen is relatively narrow.
Tunica media layer is thicker in arteries than veins.
Arteries branch as they enter tissue becoming smaller and narrower (arterioles). They regulate and slow blood flow.
447
Anastomosis
Surgical connection between 2 structures to provide an alternative route of blood flow.
Used if one branch becomes obstructed.
Kidneys, brain and heart have end arteries, they branch but dont join up together: prevents damage from sudden drop in BP (clots = fatal).
448
Veins.
Carry blood towards the heart from every tissue.
Relatively thinned walled.
Low blood pressure
Some contain semilunar vales to stop blood flowing in the wrong direction.
Low pressure so no elastic fibres and smooth muscle.
Large lumen to reduce resistance flow.
Flow is helped by contractions of the leg and abdominal muscles.
From capillaries, venules join to form veins.
449
Capillaries
Small, thin walled, permeable vessels, huge surface area: volume ratio - helps rapid diffusion of substances between blood and cells.
Blood flow is slow as they are so narrow.
Capillaries are where the transported substances enter and leave the blood.
No exchange of material takes place in arteries and veins as those walls are too thick and impermeable.
Arranged in networks called capillary beds feeding a group of cells, and no cell in the body is more than 2 cells away from a capillary.
450
Blood flow and body temperature
Body is too hot = vasodilation. Capillaries near the surface of the skin widen, blood is diverted to the skin where the heat can easily radiate away. Water from the blood is excreted as sweat to cool body.
Body is too cold = vasoconstriction. Capillaries near the surface of the skin get narrower. Blood is diverted away from the skin to limit heat loss. Sweating stops.
451
What is arteriolosclerosis?
A disease where the arteries harden or thicken.
Caused by smoking and cholesterol in the diet.
Leads to high blood pressure and increased risk of heart attack.
Fixed by a coronary artery bypass graft (CABG).
452
Blood pressure
This is the force that the blood exerts upon blood vessels in the body and is greatest in the aorta and lowest in the veins returning to the heart.
453
How is blood pressure maintained?
-neural control
-hormonal control
-angiotensinogen produced by the liver
-converted to angiotensin I by renal hormone renin and then converted to angiotensin II by angiotensin converting enzyme (ACE).
454
Open circulation
A heart that pumps fluid called haemolymph through short vessels and into a large cavity called the haemocoel, the haemolymph directly bathes organs and tissues enabling the diffusion of substances.
When the heart relaxes, the haemolymph blood is sucked back in via pores called ostia
Haemolymph moves around the haemocoel due to the movement of the organism.
455
Closed circulation
Blood is fully enclosed within blood vessels at all times.
Pumped from the heart through a series of vessels
Capillaries diffuse substances in and out of the blood and into cells.
Blood returned via heart via larger vessels.
Blood is pumped directly to organs that require it most.
456
Single circulation
Fish (bony fish/sharks) have a 2 chambered heart.
The less muscular atrium receives blood from the body and pumps it into the ventricle.
Ventricle pumps blood to capillary beds of gills
Blood exits via the aorta
Muscular contractions of body help to increase blood pressure
457
Double circulation
Mammalian circulatory system
The pulmonary circulation transports blood between the heart and the lungs (right side) whereas the systemic circulation transports blood between the heart and the rest of the body (left side).
Advantage = the 2nd pass through the heart gives the blood a boost, increases rate of flow and enables oxygen and nutrients to be delivered more quickly to cells.
458
Systemic circulation
Between heart and body
459
Pulmonary circulation
Between heart and lungs
460
Systemic circulation - arterial
Oxygenated blood = leaves via the left ventricle in the aortic arch. Branches off as coronary: two arteries which supply tissues of heart with oxygenated blood.
Brachiocephalic trunk = supplies blood to the head through the common carotid artery and also gives off the right subclavian artery which supplies the right forelimb and continues as the right axillary artery and then the right brachial artery.
Left subclavian artery = enters the forelimb through the axilla, becomes the left axillary artery and then the left brachial artery to supply blood to the left forelimb. The aorta continues through the thorax giving off paired spinal arteries to supply the various structures and muscles of vertebral column and thorax.
461
Systemic circulation - paired arteries
Hepatic = supply blood to the liver
Coeliac = stomach, liver and spleen
Mesenteric = cranial: small intestine, caudal: large intestine
Renal = supply blood to the kidneys
Ovarian and testicular = supply the gonads
Internal iliac = pelvic viscera
External iliac = branches into femoral artery
Dorsal pedal and tarsal (pulse points)
462
Systemic circulation - venous
Major veins that drain into the right atrium are:
Cranial vena cava - returns deoxygenated blood from the head, neck and forelimbs
Caudal vena cava - returns deoxygenated blood from the pelvic region, hind limbs and abdominal viscera
Azygous vein - arises in abdomen and runs towards heart passing through diaphragm. In thorax it runs dorsally and joins either the cranial vena cava or drains directly into the right atrium.
Coronary veins - venous return from the heart itself is via coronary veins which join together to form the coronary sinus which then empties into right atrium.
463
The hepatic portal system
Modified area of the systemic circulation
The liver has 2 blood supplies - hepatic artery from aorta via coeliac artery and hepatic portal vein from intestines via superior mesenteric vein.
Blood is drained from the liver by the hepatic vein, which joins with the caudal vena cava and is returned to the heart.
464
Foetal circulation
Placenta plays the part of lungs, kidneys and digestive tract.
Blood circulating through the placenta provides oxygen and nutrients and removes waste products.
Umbilical vein = carries oxygenated and nutrient rich blood to the foetus, via the foetal liver
Paired umbilical arteries = carries deoxygenated and waste product rich blood away from foetus.
Blood flow through the liver and lungs has little importance
Numerus shunts are present: foramen ovale, ductus arteriosus, ductus venosus.
465
Pulmonary circulation
Deoxygenated blood leaves the right ventricle via pulmonary artery and it travels to the lungs for gaseous exchange.
466
Function of the lymphatic system
-Returns excess fluid (lymph) back into circulation
-removes bacteria and foreign material
-produces lymphocytes
-transports products of fat digestion and fat soluble vitamins
467
Lymph
Clear to white in colour
Increase in lymphocytes
Absent in CNS and bone marrow
A one way system
Made up of lymphatic capillaries, vessels, ducts, nodes, tissues
468
Lymphatic capillaries
Smallest lymphatic vessels
Thin walled, delicate network
Called lacteals in the small intestine
469
Lymphatic vessels
Lymphatic capillaries merge
Similar structure to veins
Numerous valves
470
Lymphatic ducts
Right duct - drains R side of head, neck, thorax and right front limb into heart via right jugular/cranial vena cava
Thoracic duct - main duct. Collected blood from rest of body, arises in the abdomen as cisterna chyli (abdo,pelvis and hind limbs) once passes through diaphragm via aortic hiatus becomes thoracic. Empties into jugular/cranial vena cava.
Tracheal - head and neck, empty into thoracic duct or large veins near heart
471
Spleen (lymphatic tissue)
Largest lymphoid organ
Storage for RBC and platelets
Destroys worn out RBC
Contains phagocytic cells - filters foreign material and destroys them
Produces lymphocytes
Can rupture/develop tumors
472
Tonsils (lymphatic tissue)
Ring of lymphoid tissue in the pharynx
First line of defence against micro-organisms entering the mouth
473
Thymus (lymphatic tissue)
Very important in young
Cranial thoracic inlet
Produces T lymphocytes that form cellular mediated immune response
Regresses at puberty and often disappears.
474
Gut-associated lymphoid tissue (GALT)
Lymphatic tissue
-found in the small intestinal mucosa
-also known as Peyer’s patches
475
Structure of lymph node
-bean shaped
-numerous afferent lymphatic vessels
-Hilus drains into a single efferent vessel
-fibrous connective tissue capsule
-within the node is a network of support fibres
-lymph fluid flows through sinuses within the node
-cortex region - germinal centres or lymph nodules (produce lymphocytes)
-medulla region - macrophages (phagocytic cells)
476
Innate immunity
Built in immunity
A general immune response that is not targeted to specific antigens.
Protects from diseases from other species
477
Acquired immunity
Aka adaptive bcs it develops as we grow.
Targeted response to specific antigens ad relays on the use of antibodies.
Acquired immunity can be subdivided into active and passive immunity.
478
Active immunity
A type of immunity or resistance developed in an organism by its own production of antibodies in response to exposure to an antigen, a pathogen or vaccine.
Generally long term.
479
Natural immunity
The animal gets sick and creates its own antibodies
480
Artificial immunity
The animal creates antibodies following a vaccine.
481
Passive immunity
A type of immunity acquired by the transfer of antibodies from one individual to another
Natural - when a mother transfers antibodies to her offspring via placental route during pregnancy and via colostrum during breastfeeding.
Artificial - requires medical intervention by administering antibodies post-exposure.
482
What is the primary function for the respiratory system?
To obtain oxygen for use by body’s cells and eliminate carbon dioxide that cells produce.
483
Gases and water
Gases are soluble in water.
Increasing temperature decreases solubility
Oxygen is more soluble than nitrogen
484
Where does gaseous exchange occur?
The alveoli
485
What is the formula for exchange of gases between an animal and the environment.
Oxygen + glucose —> energy + CO2 + water vapour
486
What is the function of respiration?
Take oxygen from the air into the body (inspiration) along the respiratory passages to the areas where gaseous exchange takes place and excretes carbon dioxide from the body into the air (expiration).
Voice production (purring)
Temperature regulation
Acid-base balance
Sense of smell
487
What are the 2 stages respiration can be broken down into?
External - respiration describes the process of inspiration. It is the gaseous exchange between the air and the blood and occurs in the lungs.
Internal - respiration, also called tissue respiration is the gaseous exchange between the blood and tissues. This occurs in all tissues.
488
What can the respiratory system be divided into?
Upper = nose, nasal cavity, sinuses, pharynx and larynx
Lower = trachea, bronchi, bronchioles, lungs and alveoli
489
What does the respiratory system consist of?
Nose = the nasal cavity and turbinate bones
Pharynx = cavity at the back of mouth leading to the oesophagus and trachea
Larynx = between the pharynx and the trachea, the voice box
Trachea = the windpipe running from the larynx down the neck and into the thorax
Bronchi = divisions and branches of the trachea entering the lungs
Alveoli = tiny air-filled sacs within the lungs where gaseous exchange occurs.
490
What is the function of the nose and nasal cavity (upper respiratory tract)
Warming, filtering and moistening
The main tissue is ciliated mucous epithelium.
The nasal cavity is filled with scrolled bones called turbinates - maximises surface area.
491
External nares
Rhinarium - hairless pad of thick, stratified squamous epidermis
Contains mucus and sweat glands
Alar folds - rostral end of the ventral turbinates
Philtrum - line down to mouth
492
Nasal cavity
Cartilaginous septum
Filled with turbinates
Covered with ciliated mucous epithelium with a good vascular supply. This warms and moistens incoming air. Cilia and mucus help inhaled foreign material. Foreign material is moved into the pharynx and swallowed.
493
Defence mechanism
Mucus and cilia reduce the entry of foreign particles.
Surface antibodies are present and can be increased by using intranasal vaccines.
Sneezing results when nasal mucus membranes are irritated, prevents foreign material from being inhaled.
Dorsal turbinates = richly supplied with sensory nerves
494
Typical respiratory epithelium
The nose contains typical respiratory epithelium (TRE)
TRE = ciliated pseudo-stratified columnar epithelium with goblet cells scattered throughout.
Found throughout the length of the air passages in the respiratory tract.
The serous and mucus secretions catch and hold any dirt particles/bacteria inhaled.
495
Sinuses
An air-filled cavity lying within a bone.
Connecting to each nasal cavity are 2 sinuses.
The frontal sinus - lies within the frontal bone of the skull, above and between the eyes.
The maxillary sinus - lies between the maxillary bone and the palatine bone just below each eye. (Not a true sinus as not completely enclosed in one bone).
496
Pharynx
Shared with the digestive system.
Split into: nasopharynx dorsally and oropharynx Ventrally
Split by musculomembranous soft palate.
Eustachian or auditory tubes enter the pharynx from the middle ear - ensure air pressure is equalised to protect the tympanic membrane
Split into 3 areas:
Nasopharynx
Oropharynx
Laryngopharynx
497
Degultition mechanism.
The oral phase (swallowed, chewed, prepared into a ‘pellet’)
The pharyngeal phase
The oesophageal phase
498
Larynx
A moveable framework of cartilage, vocal cords and muscle that connects the pharynx and trachea.
Function = to ensure that only gases pass down into the lower respiratory system.
Larynx closes as soon as food particles touch the epiglottis.
Also the voice box
Suspended from the skull by the bony hyoid apparatus.
499
Epiglottis
Made of elastic cartilage
Attached to the entrance of the larynx
While breathing it lies completely within the pharynx - whilst swallowing it serves as a part of the larynx
500
Laryngeal cartilage
Epiglottis - most rostral cartilage, seals during swallowing
Thyroid - largest, forms the floor
Arytenoid - side, supports the vocal cords
Cricoid - ring structure
501
Hyoid apparatus
Made up of a number of bones that are fine in structure.
They are joined by a cartilaginous joint.
Found at the cranial end of the neck region.
Suspension mechanism for the tonnage and larynx.
502
Trachea
Runs from the larynx to the lungs
Held permanently open by rings of hyaline cartilage, between these rings are annular ligaments made up of fibrous connective tissue and smooth muscle.
Lined with cilia to help remove debris known as ‘muco-ciliated escalator’
Once in thoracic cavity branches into 2 tubes just above the heart (the left and right bronchi)
503
Bronchi
Continuation of the trachea
Held open by thin rings of cartilage
Each bronchi enters a lung - they subdivide and become progressively narrower to bronchioles then alveoli, forming a bronchial tree
504
What do the terminal bronchus narrow into?
The alveolar duct, this leads to an alveolar sac from which branch several alveoli.
505
Alveoli
Lined with simple squamous epithelium
Tiny capillaries surround each alveolus - where external respiration occurs.
One cell thick, large surface area - allows for more efficient gaseous exchange
On the outside is a dense network of blood capillaries which originate from the pulmonary artery. (Gaseous exchange takes place here)
506
Lung lobes
Cranial - apical
Middle - cardiac
Caudal - diaphragmatic
The right lung has a 4th lobe - accessory
507
The lung
Contains no muscle
Cannot expand on its own
Very elastic - returns to a collapsed state when there is nothing to expand it
508
Gaseous exchange
Alveoli provide a large surface area for gaseous exchange.
When an animal breathes in, the oxygen in this air diffuses across the thin pulmonary membrane into the blood capillaries surrounding the alveoli.
The oxygenated blood travels around the body to the tissues.
Carbon dioxide diffuses from the blood into the lungs and passes out in expired air.
509
Define tidal volume
The amount of air that moves in or out of the lungs with each respiratory cycle
510
Define residual volume
The volume of air remaining in the lungs after maximum forceful expiration
511
Define minute volume
The amount of gas inhaled or exhaled from a persons lungs in 1 minute
(Tidal volume X respiratory rate)
512
Define total lung capacity
The volume of air in the lungs upon maximum effort of inhalation
513
Define expiratory reserve volume (ERV)
The volume of air that can be forcefully exhaled after a normal resting expiration.
Leaving only the residual volume in the lungs
514
Define inspiratory reserve volume (IRV)
The extra volume of air that can be inspired with maximal effort after reaching the end of a normal, quiet inspiration
515
Define vital capacity
The greatest volume of air that can be expelled from the lungs after taking the deepest breath possible
516
Define functional residue capacity (FRC)
The volume remaining in the lungs after a normal passive exhalation
517
Define dead space
The volume of ventilated air that doesn’t participate in gas exchange
518
Normal respiratory rates
Dog = 10-30 brpm
Cat = 20-30 brpm
Rabbit = 35-60 brpm
Guinea pig = 60-140 brpm
Rat = 60-140 brpm
Mouse = 100-280 brpm
Hamster = 74-80 brpm
519
Mechanism of respiration
Inhalation = Diagramm contracts pulling it from its relaxed position to more flattened. This increases the length of the thoracic cavity. At the same time the external intercostals muscles contract, pulling the ribs upward and outwards - this acts to increase the volume of the thoracic cavity and decrease pressure inside. Air is drawn in via the trachea to accommodate the reduced pressure.
Exhalation = diaphragm relaxes and returns to its dome shaped position. The external intercostals relax and ribs fall back. Both the ribs and diaphragm act to decrease the volume and increase the pressure in the thorax. Air is driven out through the trachea.
520
Control of respiration - neural
Lungs inflate
Receptors of the bronchi and bronchioles send impulses to the respiratory centre in the medulla and pons of hindbrain.
Inhibits respiration and stimulates expiration
This is the Hering Breuer reflex
When lungs deflate, the respiratory system initiates the next inspiration.
This is the deflation reflex.
521
Control of respiration - hormonal
Respiration is controlled by chemicals in blood for example - carbon dioxide
This is monitored by medulla of hindbrain
When carbon dioxide increases in the blood, ventilation will increase, resulting ion levels in the blood decreasing
Oxygen levels are monitored by chemoreceptors in the carotid arteries and aortic arch
522
What is the endocrine system?
A series of ductless endocrine glands which are situated throughout the body, each secreting a different hormone.
523
What does the endocrine system do?
Forms a part of the regulatory system.
Works with the nervous system to maintain homeostasis.
Endocrine response = slow onset but lasts longer period of time
Nervous response = rapid and short lasting
524
Hormonal secretion methods
Transported via the blood to organs and around the body
Metabolic = acting as a catalyst in a reaction
Kinetic = resulting in substances moving around the body
Behavioural = mating behaviour
Changing = the appearance or structure of tissue (mammary development)
525
Exocrine glands
1. Produce secretions released outside the body or into the GI tract
2. Always have a tube or opening or duct
3. Gland products are localised to region around duct
Example = sweat glands
526
Endocrine glands
1. Also called ‘ductless glands’
2. Hormone-producing cells secrete hormones directly into bloodstream
3. Chemicals circulate through whole body
Example = adrenal glands
4. Help control many body functions
527
Hormones
Chemical agents produced by one organ and secreted directly into the blood stream.
Only the organs that have the specific receptors respond to the hormone
They are rapidly destroyed so that new messages can be sent
Involved in homeostasis and adaption.
528
Stimulus of hormone secretion
Occurs in response to a specific stimulus:
Nerve impulses - adrenaline is released in response to nerve impulses
Stimulating/releasing hormone - TSH activates the thyroid gland
Levels of certain chemicals in the blood - raised blood glucose stimulates release of insulin from the pancreas
Feedback loops - prevents over secretion
529
What hormones are not secreted by the endocrine glands?
Gastrin
Secretin
Chorionic gonadotrophin
Erythropoietin
530
Functions under endocrine control
Digestion related metabolic processes
Osmoregulation excretion (H20, salt metabolism)
Calcium metabolism
Growth and morphological changes
Reproductive organs, reproduction
531
3 distinct endocrine hormone groups
Amines derived: adrenaline, thyroxine, dopamine
Steroids: testosterone, oestrogen, progesterone, corticosteroids
Peptides: TSH, oxytocin
Proteins: growth hormone, insulin, ACTH
532
Homeostasis and the hypothalamus
(Endocrine system)
Hypothalamus is a major control centre for homeostasis
Constantly regulates functions using both nerves and hormones
Functions controlled: temp, hunger/thirst, sex, sleep, fight or flight, levels of hormones
Hormonal control is exerted via anterior and posterior pituitary
Control of endocrine glands by hormones of the anterior pituitary - ACTH, TSH, FSH, LH
The hypothalamus controls the anterior pituitary through a series of releasing hormones: RHs
533
What are negative feedback loops?
The mechanisms change the variable back to its original state or ‘ideal value’
534
What is positive feedback ?
Increased levels of a hormone are detected by a gland and result in even more hormone being produced by that gland.
535
What endocrine glands are in the body?
Pituitary gland (anterior and posterior)
Thyroid gland
Parathyroid gland
Adrenal gland (cortex and medulla)
Pancreas
Ovaries
Testes
536
Define target tissue
Many target tissues modify their response locally by multiple mechanisms to provide homeostasis
537
Pituitary gland
Ventral to hypothalamus in forebrain
AKA ‘Master gland’
Has 2 lobes - anterior and posterior
Anterior - a classical gland composed predominantly of cells that secrete protein hormones (7)
Posterior - an extension of the hypothalamus and main function is to store hormones
538
Pineal gland
Located within the brain
Produces melatonin in response to daylight length
Functions: body related to the photoperiod (reproductive behaviour, coat changes)
539
Anterior pituitary hormones
(Cranial end of the pituitary, larger gland - situated at the base of the hypothalamus)
Thyroid stimulating hormone (TSH)
Adrenocorticotrophic hormone (ACTH)
Growth hormone (GH) ‘’AKA’’ somatotropin
Follicle stimulating hormone (FSH)
Luteinising hormone (LH)
Interstitial cell stimulating hormone (ICSH) (male version of LH)
Prolactin
540
Posterior pituitary gland hormones
(Caudal end of the pituitary gland, smaller, situated at the base of the hypothalamus)
Antidiuretic hormone (ADH) aka vasopressin
Oxytocin
541
Thyroid gland
Positioned in the neck, ventral midline
Butterfly shaped
Releases hormone responsible for metabolism
Stimulated by TSH
Needs iodine, lack of affects thyroid
Releases 3 hormones: thyroxine (T4), Tri-iodothyronine (T3), Calcitonin
542
Parathyroid gland
Situated either side of the thyroid gland
Produces parathyroid hormone (PTH, parathormone)
Secreted in response to low blood calcium and stimulates resorption of bone and increased intestinal calcium absorption.
543
Pancreas
(Endocrine system)
Pink, lobular gland
Location: Caudal end by the duodenum
A mixed gland: exocrine = digestive pancreatic juices and endocrine = Islets of Langerhans secrete hormones:
Insulin (beta cells), Glucagon (alpha cells), Somatostatin (delta cells)
544
Adrenal glands
Situated on the cranial end of the kidneys, secretes 3 main hormones.
adrenal cortex: Glucocorticoids and Mineralocorticoid (aldosterone)
Adrenal medulla: adrenaline and noradrenaline
545
Ovaries
(Endocrine system)
Location: lie each side of the dorsal abdomen, just caudal to the kidney. Begin to secrete hormones once animal has reached maturity.
Oestrogen and progesterone
546
Testes
(Endocrine system)
Male reproductive glands, present within scrotum, external to abdominal cavity.
Secrete hormones at maturity
Testosterone and oestrogen
547
Other endocrine activity
Gastrin = secreted by food entering stomach, stimulates release of gastric juices from glands
Secretin = secreted by food entering duodenum, stimulates release of intestinal and pancreatic juices.
Chorionic gonadotropin = ectodermal layer of chorion surrounding foetus. Maintains corpus luteum in ovary throughout gestation.
Thymosin = promotes development and maturation of lymphocytes. Contributes to immune response.
Calcitrol = active form of Vitamin D. Produced in the kidneys, increases absorption of calcium and phosphate from digestive tract.
Erythropoietin = kidneys: released when blood oxygen is low. Stimulates bone marrow to produce red cells.
548
What are the 2 major functional subdivisions can of urinary system?
1. The kidneys
2. Excretory passages
549
Functions of the urinary system
Maintain homeostasis
Excretion - remove nitrogenous waste products and excess water from the body
Osmoregulation - this keeps the chemical composition and column of the blood constant by eliminating excess water and salts
Endocrine gland - secretes the hormone erythropoietin which stimulates the bone marrow to produce RBCs
550
Toxin breakdown
(Urinary system)
Excess amino acids and proteins produce waste —> toxin called ammonia —> toxins filtered and converted by liver —> less toxic urea and uric acid —> filtered by kidneys —> excreted as urine
551
Structure of the urinary system
Lies in the abdominal and pelvic cavities
Anatomically linked with the genital or reproductive system.
2 kidneys
2 ureters
1 bladder
1 urethra
552
Structure of the urinary system
Lies in the abdominal and pelvic cavities
Anatomically linked with the genital or reproductive system.
2 kidneys
2 ureters
1 bladder
1 urethra
553
The kidneys
Bean shaped organs
Cranial abdomen, either side of midline
Ventral to lumbar hypaxial muscles (the left is more caudal)
Retro peritoneal
Adrenal glands close to cranial pole of kidney
Surrounded by a layer of protective fat
554
What is the hilus
(Kindeys)
An indented area on the kidneys
Where blood vessels, nerves and ureters enter and leave
555
What are the 4 distinct parts of the kidney
Cortex - outer part
Medulla - middle part
Renal pelvis - inner part
Capsule - external layer of fibrous connective tissue protecting the kidney
556
What filters waste from the kidneys?
Nephrons
Blood is filtered and urine is produced
557
What does a nephron consist of?
Glomerular or Bowman’s capsule
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule
Collecting duct
558
Blood supply to the kidneys
Arterial supply comes from the aorta into a renal artery
Carries 20% cardiac output
Once it enters the kidney the renal artery divides into several interlobular arteries - these pass between renal pyramids and into the cortex where they split into capillaries supplying renal tubules and the glomerulus.
Each glomerulus supplies a single nephron, they then form interlobular veins, finally forming a sigle renal vein which joins the caudal vena cava
Blood entering the kidneys contains O2, nutrients, waste products from the body
Blood leaving the kidneys contains CO2 from the kidney tissue but the nitrogenous waste has been filtered out by the glomerulus.
559
What is the glomerular capsule or Bowman’s capsule ?
Encloses a network of capillaries known as the glomerulus
A capsule and a glomerulus together form a renal capsule
560
What is the proximal convoluted tubule
Lined with microvilli
Water and electrolytes reabsorbed here
561
What is the Loop of Henle?
Concentration of urine is regulated here
562
What is the distal convoluted tubule
Not lined with microvilli
The final adjustments are made to the electrolyte content of the urine here
563
What is the collecting duct ?
Collects urine from several nephron and empties into the pelvis of the kidney
564
The glomerulus
The arterioles have a lot of divisions and coils which create a knot of blood vessels and this is called the glomerulus
It sits in a cup made of squamous epithelial tissue known as the Bowman’s capsule
565
What are the blood vessels called involved in the glomerulus ?
Afferent arteriole = enters
Efferent arteriole = exits
The afferent arteriole is much thicker than the efferent arteriole.
Because of the size difference in vessels the blood in the glomerulus is under high pressure.
The high pressure forces fluid and small molecules out of there blood and into the bowman’s capsule
Cells like RBCs and plasma proteins are too large to pass through and so remain in the circulation.
This process is known as ultrafiltration and the fluid produced is called the glomerular filtrate.
The fluid now passes into the rest of the nephron for more filtering
566
What does the proximal convoluted tubule (PCT) do?
Long-twisted tube leading from the neck of the Bowman’s capsule.
Lies in the renal cortex.
Most reabsorption happens here (most sodium ions and water and all glucose in the filtrate)
These are all reabsorbed into the fluid surrounding the PCT and back into the blood
The remaining filtrate continues to the Loop of Henle
567
Function of the Loop of Henle
U-shaped
Has 2 parts - descending and ascending
Filtrate becomes concentrated in the Loop of Henle, this conserves water and minimises the volume of urine.
Descending limb = permeable to water and filtrate becomes more concentrated
Ascending limb = impermeable to water, contains sodium pumps, filtrate becomes less concentrated
568
Function of the distal convoluted tubule (DCT)
Shorter and less twisted than the PCT
The DCT is responsible for the regulation of pH, potassium, sodium and calcium
It is here that final adjustments are made to the electrolyte content of the urine according to the status of the ECF.
These adjustments are made by selective reabsorption and active secretion of certain compounds.
569
Selective reabsorption
Most of the sodium in the filtrate has been reabsorbed back into the blood by active sodium pump in the Loop of Henle. Any remaining sodium ions are absorbed here under the control of the hormone aldosterone .
Calcium ions are also reabsorbed under the control of the endocrine system
570
Active secretion
The DCT may also secrete compounds if their concentration becomes too high within the renal tubules.
The DCT regulates blood pH in this way.
These compounds include drugs and hydrogen ions.
It is through active secretion of hydrogen ions that the kidneys have a direct effect upon blood pH and the maintenance of homeostasis and the acid/base balance.
571
Collecting ducts
The filtrate from several nephrons passes into a collecting duct. From here it is conducted to the renal pelvis
Final adjustments are made to the volume of the filtrate in response to the status of the ECF.
The volume of water is adjusted under the control of ADH
ADH is produced by the posterior pituitary gland and changes the permeability of the duct walls to water.
572
Define uraemia
State of toxicity resulting when the kidney isn’t able to filter blood adequately
573
Define diuresis
Therapy where extra fluid is provided thus giving the kidney its excretion medium to remove toxic waste
574
Define dialysis
Use of a fluid (dialyser) to force the diffusion of certain solutes from the blood.
Can be peritoneal or haemodialysis
575
What is urine made up of?
96% water and 4% solids
These solids inc = urea, urates, uric acid (all end products of protein metabolism), chlorides, phosphates, sulphates and oxalates of sodium, potassium, calcium and creatinine.
576
What is the average pH of urine?
5-7pH
Dog = 6.5
Cat = 6
577
Urine formation
The kidneys filter the blood
Filtrate undergoes changes in the kidney to form urine - For every 100L of blood filtered, 1L is excreted as urine.
Blood enters kidney via renal artery - reaches capillaries of renal artery.
Blood is under high pressure which forced fluid and small molecules out of the glomerulus into the lumen of the Bowman’s capsule - larger molecules are retained in the blood. (Known as ultrafiltration)
The fluid is now called glomerular filtrate.
The filtrate reaches the PCT, where sodium ions, 65% water and all glucose is reabsorbed.
Some urea diffuses back into the blood, drugs and toxins are secreted.
The filtrate now reaches the Loop of Henle and flows down the descending loop and water is reabsorbed.
The filtrate flows up the ascending loop and sodium ions are reabsorbed.
Result = concentration of filtrate is the same when it leaves the loop so when it enters but the volume is reduced and water has been conserved.
The filtrate now reaches the DCT where final adjustments are made to the electrolyte content.
Sodium is reabsorbed and replaced in the urine by potassium. Reabsorption of water is controlled by aldosterone.
The acid/alkaline balance is controlled by excreting hydrogen ions.
The filtrate now reaches the collecting duct where final adjustments are made to the volume of the water in urine.
578
What is the anti-diuretic hormone able to do?
Alter the permeability of the walls of the collecting ducts. The urine is then collected in the renal pelvis and leaves the kidney via the ureter.
579
The ureters
There are 2
One from each kidney
Lie each side of midline dorsal abdomen suspended in visceral peritoneum.
Thick walled, lined with mucous membrane
Wall contains smooth muscle tissue
Urine moves along the ureters using peristalsis
Enter bladder on dorsal aspect
Flap valve prevents urine back flow - ureterovesical valve
580
The bladder
A triangle shaped storage organ
Located in lower abdomen
A reservoir for urine
Extends into the abdominal cavity Ventrally over pelvic brim but lies mostly within the pelvic cavity
Rounded end cranially, narrow end or neck Caudally
Bladder wall consist of - transitional cell epithelium, submucosal layer of elastic tissue and smooth muscle
Its capable of considerable distension
The walls contain stretch receptors (sensory nerves) to indicate to the animal the need to urinate.
Has a strong muscle at the exit of bladder known as sphincter muscle which retains urine within the bladder until urination
Sphincter consists of - internal sphincter under involuntary control and external sphincter under voluntary control.
The section between the ureter entry area and the neck of the bladder is known as the trigone. This acts as a valve to prevent back flow of urine along the ureter.
581
Micturition
Correct term for passage of urine.
Normally a reflex activity but can be overridden by voluntary control from the brain.
Voluntary control is not fully developed until 10 wks of age in puppies and kittens.
582
The urethra
A tube that conducts urine from the bladder to the outside.
Its structure varies according to the sex of the animal and species (male cats and dogs)
583
Female urethra
Short
Opening onto the floor of the reproductive tract between the vagina and vestibule.
Ridge called urethral tubercle
External urethral orifice = useful landmark when catheterising a bitch.
584
The male urethra
Near the bladder neck are 3 openings into the urethra:
-prostate gland
-2 deferent ducts; joined by erectile tissue forming the penis, at ischial arch
The urethra is divided into 2 parts - the pelvic urethra and the penile urethra
Tom cat:
Urethra runs a little distance before joined by prostate and deferent ducts
Preprostatic urethra
Then joined by duct bulbourethral glands
Opens onto perineal region, ventral to anus
585
Osmoregulation - control of water in the body
Water taken in by food and water and excreted in urine, faeces, sweat and respiration.
Other factors can cause a decrease = shock, dehydration, blood loss, haemorrhage, v+ and d+
Renin = produced by glomeruli, due to fall in arterial pressure
Angiotensinogen = converted to angiotensin by renin
Angiotensin = causes vasoconstriction, stimulates adrenal cortex to release aldosterone
Antidiuretic hormone (vasopressin) = from posterior pituitary gland, increases water permeability of collecting duct.
Baroreceptors = walls of blood vessels, detects pressure change
Osmoreceptors = in the hypothalamus, monitors plasma osmotic pressure, controls thirst and ADH release
Renal function, or Osmoregulation ensures - plasma components and volume and tissue fluid remains constant (homeostasis), controlling water and salt loss from body.
586
What 3 hormones does the kidney produce?
Erythropoietin (EPO) - travels to bone marrow to stimulate RBC production.
Vit D - an active hormone, converted into its strongest form in the kidneys. Crucial role in bone metabolism and regulates the body’s metabolism of calcium and phosphorus.
Renin - helps to control blood vessel stability and to regulate blood pressure. Formed in specialised cells in the kidney.
587
Excretion of nitrogenous waste
Amino acid leave gut to liver - converted to body proteins
Excessive amino acids broken down - deamination, producing ammonia, extremely toxic to tissues
Ammonia is combined with carbon dioxide by liver forming urea (ornithine cycle)
CO2 + 2 NH3 = CO(NH2)2 + H2O
NH3 = ammonia
CO(NH2)2 = urea
588
What is involved within the male reproductive system?
scrotum
2 testes
2 epididymis
2 vas deferens
Prostate
Penis
Prepuce
Urethra
589
Scrotum
Testicles lie within the scrotum
A membranous pouch divided by a septum into 2 halves
Dartos muscle within the scrotal wall - function: retracts scrotum towards body when cold
Contains smooth muscle allowing the position of the testicles to change depending on temp.
590
Testicles
2 testes
Can be referred too as gonads or testicles.
Each testicle is oval shaped.
Wrapped in a double layer of peritoneum known as tunica vaginalis.
During growth they descend from the abdomen, through the inguinal ring in the wall of the abdomen
591
Define cryptorchid
One or both testicles retained
592
Define monorchid
Only one testicle developed
593
What is the function of the testicles?
To produce sperm by the process of spermatogenesis
To produce fluid to transport the sperm - aids in sperm survival
To secrete testosterone to influence sperm development and male behavioural patterns
594
What do the Cells of Leydig secrete
Also called interstitial cells.
Stimulated by the anterior pituitary gland to secrete testosterone.
595
Epididymis
A large coiled tube that lies along the testis.
Acts as a storage area for sperm and where they undergo a period of maturation.
596
The vas deferens (spermatic cord)
Carries sperm from the epididymis through to the urethra via the prostate gland (bulbo-urethral gland in the cat).
Within the spermatic cord there are:
-Testicular artery and vein
-nerve
-cremaster muscle
597
Accessory glands
Secretes seminal fluid
Increases ejaculate volume
Helps sperm pass successfully into female
Provides optimum environment for sperm during transfer
Neutralises acidity of urine within urethra.
598
Prostate gland
Bi-lobed structure about the size and shape of a walnut and surrounds the urethra at the level of the pelvic bone.
Lies just below the neck of the bladder in a dog and a little further down the urethra in the cat.
Prostate produces a milky white fluid that forms part of the seminal fluid, this makes up a volume of the ejaculate.
Aids the survival of the sperm by being slightly alkaline and providing enzymes energy.
599
The bulbo-urethral gland
Present in the CAT only
Lies caudal to the prostate gland along the urethra
Secretes a thick mucus substance that forms part of the seminal fluid in the cat
600
The penis and prepuce
Functions of penis: convey sperm and fluids from the testis into the female reproductive tract
Convey urine from the bladder to the outside via the urethra.
Tubular organ. Consist of the root, body and glans.
Small bone that develops which is unattached to the rest of the skeleton, referred to as the splanchnic skeleton and the bone is called the os penis.
Dog - penis points cranially from between the hind legs. The distal part is contained within the prepuce which is lined with epithelial tissue - its function is to cover and protect when the penis is not erect.
Os penis lies dorsal to the urethra and has a groove in which the urethra is located with the function of aiding entry into the female reproductive tract when mating.
Cat - penis is shorter and points Caudally. The external opening is ventral to the anus. The tip of the glans penis is covered with tiny barbs which elicit a pain reflex as the male withdraws from the female, this stimulates ovulation within 36 hours. (Induced ovulation)
During sexual excitement the penis points cranioventrally allowing the tomcat to mate in a similar way to the dog.
601
Hormone Control (reproductive system)
Formation of spermatozoa begins at puberty when there is a stimulation by the pituitary gland for the stimulation of the cells of Leydig to produce testosterone.
Rising levels of testosterone result in production of spermatozoa and the resulting in male characteristics.
Sertoli cells provide support for the development and maturation of spermatozoa.
They’re stimulated by FSH from the anterior pituitary gland and produce inhibin (a hormone that has negative feedback on the production of FSH)
602
Structure of a spermatozoon
Acrosome = protects head of spermatozoon, contains enzymes
Head = contains haploid number of chromosomes
Midpiece = contains enzymes and mitochondria (energy for movement)
Tail = powerful propulsive force
603
What is involved in the female reproductive tract ?
2 ovaries
2 fallopian tubes (oviducts)
The uterus (has horns, body and cervix)
The vagina
The vestibule
The vulva
604
What supplies blood to the female reproductive tract ?
Ovarian artery - from aorta just caudal to renal artery. Supplies ovary, uterine tube and horns
Uterine artery - forms anastomoses with ovarian artery. Supplies caudal portion of tract
605
The ovary
Ovaries produce sex cells called ova, they’re transported by the fallopian tubes to the uterus.
Implantation takes place if fertilisation has occurred and the embryo is developed.
Located in the abdominal cavity caudal to the kidneys.
Source of oestrogen and progesterone.
Made up of connective tissue, smooth muscle, blood capillaries and large number of germ cells and developing follicles.
Attached to various areas of the abdomen by ligaments to ensure they remain their position but permit stretch during pregnancy.
606
What ligaments attach the ovary to the abdominal wall?
Suspensory ligament - attach the ovary to abdominal wall
Round ligament - attached to the inguinal ring
Broad ligament - attached to the uterine tube (oviduct) and is continuous
607
What is the ovary divided into ?
Medulla - contains blood vessels, nerves, lymphatics, muscle and connective tissue
The cortex - a connective tissue ‘stroma’ which contains large numbers of germ cells
608
What is the mesovarium
Encloses the ovary and its nearby uterine tube in a section of visceral peritoneum.
Forms a pocket like structure known as the ovarian bursa which completely covers the ovary.
609
The oviduct/fallopian tube
Constructed of smooth muscle and lined with ciliated columnar epithelium.
Surrounding peritoneum is called the mesosalpinx.
At ovulation the infundibulum lies very close to the ovary. Modified with fimbriae to catch the ovaries which are then directed down into the oviduct using peristalsis.
610
The uterus (uterine horns)
Hollow Y shaped organ
Comprises of: body, 2 uterine horns, mesometrium or broad ligament.
The wall of the uterus has 3 layers: perimetrium - outer serosal layer. myometrium - compromises layers of smooth muscle that produces strong contractions during parturition. Endometrium- lining of columnar mucous membrane, glandular tissue and blood vessels, thickens to provide nutrition to the embryo.
611
What is the mesentery of the uterus also called?
Broad ligament
612
What is the term for an animals first pregnancy?
Primigravida
613
What is the term for an animal who’s had several pregnancies ?
Multigravida
614
The cervix
Short thick-walled muscular sphincter that connects the uterine body with the vagina.
Sphincter is normally tightly closed and only relaxes to allow the passage of sperm or foetuses.
During pregnancy the opening is blocked by a mucoid plug which protects the ova from infection, during parturition this plug comes away and the cervix increases in dilation.
615
The vagina, vestibule, and vulva
Lined with stratified squamous epithelium.
Vagina leads to vestibule forming a channel to the external urethral orifice where the urinary and reproductive systems join.
Vestibule - extremely muscular. Contributes to the tie in dogs during mating by tightening onto the penis.
Vulva - marks the external opening of the urogenital tract. Consists of 2 folds of skin known as the labia.
616
Ovulation
Surface of the ovary is covered with a layer of germinal epithelium from which germ cells arise.
Germ cells initially develop into many primary ovarian follicles which develops into a Graafian follicle.
When a batch of follicles ripen, they come to the surface of the ovary where they rupture and release the developed ova into oviducts (known as ovulation).
The ova are captured by the fimbriae of the infundibulum of the oviducts.
Once the follicle has released the ovum, the follicle remnants change structure into corpus luteum, and then reabsorb into corpus albicans (scar tissue).
617
Mammary glands
Modified cutaneous glands found on the ventral wall of the abdomen and thorax, each side of the midline.
Made up of glandular tissue within connective tissue and lined with a secretory epithelium causing mammary gland enlargement during pregnancy.
Milk drains through sinuses to teat canal, to teat orifices and is produced in response to 3 hormones; progesterone, prolactin, oxytocin.
618
What is the function of the nervous system ?
To receive information from external and internal stimuli
To interpret and integrate information received
To bring about necessary response
619
What are the 6 types of neuroglia cells?
Ependymal - line cavities called ventricles. Filter some material out.
Oligodendrocytes - wrap around axons of CNS neurons providing insulation
Astrocytes - cell extensions called processes for chemical exchanges. These processes connect with neurons and other tissues.
Microglia- resident macrophages of CNS. Responsible for maintenance of CNS tissue.
Satellite cells - provide nutrients and protection to neurons in PNS. Wraps around body.
Schwann cells - wraps around the axons of neurons. Forms myelin sheath which is a protective layer.
620
Sensory nerves
Afferent
Designed to pick up stimuli and send the impulse up its axon to the cells body in the CNS.
Found in the skin, muscles, bones, internal organs and part of a specialised sense organ.
621
Connector or intercalated neuron
Pass the electrical impulse along nerve cell called intercalated fibres/neurons to other neurons in the CNS.
Neurons in the brain and spinal cord that conduct impulses between neurons such as afferent and efferent neurons.
622
Motor neuron
Efferent
Send the electrical impulse down their axon, to a muscle or gland to promote an action.
623
Visceral fibres
Found in internal organs, smooth muscles and glands
Send electrical impulses to the CNS in response to changes in these organs and the visceral motor fibres cause muscles in the internal organs to move and glands secrete
624
Somatic fibres
Found in the skin and musculoskeletal system
Somatic sensory fibres give the animal its sense of touch
Somatic motor fibres allow it to carry out voluntary movement, they are under the animals conscious control.
625
Define ganglion
Collection of cell bodies outside the CNS
626
Define receptor
Sensory nerve ending - specialised to detect changes and trigger impulses in sensory fibre
Eg: temp, taste, vision etc
627
Define effector
Muscle or gland, which carries out an activity, instructed by the nervous system.
628
Define a synapse
Impulses passed from one neurone to another
629
Define a neuro-muscular junction (NMJ)
An impulse passed from a neuron to a muscle fibre
630
How is information transferred ?
(The nervous system)
Synapse
Electrical and chemical
Voltage-gated channels open or close in response to a change in the voltage across a plasma membrane
Chemically gated channels open or close depending on the presence or absence of a specific chemical that binds to the channel protein.
631
Define resting potential
The electrical potential of a neuron when not stimulated or involved in a passage of an impulse
632
Define action potential
Initiated when the membrane potential of a neuron reaches a certain threshold level.
633
Define neurotransmitter
Endogenous chemicals that allow neurons to communicate with each other throughout the body.
634
What is depolarisation
Where the inside of a neuron becomes less negative in comparison to its resting condition, its plasma membrane is depolarised.
635
What is hyperpolarised ?
When the inside of a neuron becomes more negative in comparison to its resting condition, its plasma membrane is said to be hyperpolarised.
636
Eletrical messages
(The nervous system)
1. Action potentials arrive at axon terminal
2. Voltage-gated Ca2+ channels open
3. Ca2+ enters the cell
4. Ca2+ signals to vesicles
5. Vesicles move to the membrane
6. Docked vesicles release neurotransmitter by exocytosis
7. Neurotransmitter diffuses across the synaptic cleft and binds to receptors
637
What is involved within the central nervous system ?
Brain and the spinal cord
638
What is involved in the peripheral nervous system?
All other nerves and neurons that do not lie within the CNS
639
What is grey matter ?
Has cell bodies with little or no myelin
In the brain it’s mainly peripheral and forms an island with white matter
In the spinal cord it forms a butterfly shaped core surrounded by white matter.
640
What is white matter?
Consists of myelinated nerve cell processes
641
What types of cells make up the brain?
Glia = supports anf protects the neurons
Neurons = carry information in the form of electrical pulses known as action potentials.
642
Structure of the brain
Forebrain = cerebrum,thalamus and hypothalamus
Midbrain
Hindbrain = medulla oblongata, pons, cerebellum
643
Cerebrum
In the forebrain.
90% of neurons are found here.
Divided into right and left cerebral hemispheres - connected by a thick band of neurons called corpus callosum.
Function is to maintain a flow of information between the 2 halves of the cerebrum.
644
What are the folds called on the surface of the hemispheres ?
Gyri - folds in cerebral hemispheres
Sulci- shallow grooves separating the gyri
Fissures - deep grooves separating the gyri
Longitudinal fissure - prominent groove that divides the cerebrum into right and left cerebral hemispheres.
645
Thalamus
Deep in posterior forebrain
Processes information from sense organs
Passes information between cerebrum and brainstem
646
Hypothalamus
Lies ventral to the thalamus and dorsal to the pituitary gland
Functions:
Provides a link between the nervous and endocrine systems
Helps control the autonomic nervous system
Homeostasis
647
Midbrain
Short length of tissue between forebrain and hindbrain
Cerebral hemispheres lie dorsally
Passes impulses between the hind and the forelimb
Also called mesencephalon
648
Cerebellum
Hindbrain
Dorsal aspect
Coordinates balance and muscular movement
649
Pons
Hindbrain
Bridge of nerve fibres between L and R cerebellar hemispheres - ventral to cerebellum.
Part of the brainstem and sends messages through the brain
Brain cannot function without pons
650
Medulla oblongata
Hindbrain
Extends from the pons
Control of respiration and blood pressure
If damaged the animal will be brainstem dead
651
Cranium
‘Bony shell’
Protects the brain from damage
652
Ventricular system
Series of interconnecting canals, cavities and ventricles inside the brain and spinal cord.
Filled with CSF
Also surrounds the brain
653
Cerebrospinal fluid (CSF)
Brain is suspended within CSF
Clear liquid
Formed by choroid plexuses
Found in the subarachnoid space
Functions; protect the brain and spinal cord. Supply nutrients to the nervous tissue.
654
Meninges
Membranes that separate the skill from the brain. Consists of 3 membranes:
Dura mater - thick tough fibrous connective tissue layer under bones of the skull.
Arachnoid mater - network of collagen fibres and blood vessels supplying nervous tissue
Pia mater - delicate membrane. Contains small blood capillaries.
655
The spinal cord
Extends from medulla oblongata to the lumbar region of the vertebral column.
At approx L6-L7 it terminates by breaking up into mixed nerves.
Made up of: CSF, grey matter and white matter.
656
The cranial nerves
12 pairs of nerves leaving the brain
Either sensory, motor or mixed
Each has a name and a Roman numeral.
Sensory - organs to the brain
Motor - brain to the organs
657
Spinal nerves
Dorsal root - carries sensory fibres from the body towards the spinal cord
A few mm from the cord is the dorsal root ganglion, a swelling containing all the cell bodies of these neurons .
Ventral root - carries motor fibres away from the spinal cord towards the organs
658
Autonomic nervous system
Involuntary part - homeostasis occurs
Consists of visceral motor nerves running from brain to viscera of the body.
Then divided into sympathetic and parasympathetic
659
Sympathetic nervous system
Responds to impending danger or stress
Responsible for increase of heart rate and blood pressure.
Acetylcholine between the cell body and the dendron
Noradrenaline between axon and the organ
Fright, flight and fight
660
Parasympathetic nervous system
Resting/relaxed
Responsibilities = constriction of pupil, slowing hr, dilation of blood vessels etc
661
Reflex arc
Involuntary automatic response
Reflexes can be unconditional or conditional
May be monosynaptic or polysynaptic
662
Monosynaptic arc
Eg patella reflex
When the tendon is lightly stretched the muscle fibres stretch.
A response is initiated in muscle spindles and passed onto the sensory nerve.
Sensory nerve synapses with motor nerve which causes a contraction and the leg kicks out.
Chemical transmission so very rapid
663
Polysynaptic reflex
Withdrawal reflex
Involves one or more intercalated neurons and several synapses in the pathway.
Move limb away before brain has received pain message.
664
Clinically relevant peripheral nerves
Forelimb!
-brachial plexus
-radial nerve
-median nerve
-ulnar nerve
Hindlimb!
-sciatic nerve
-femoral nerve
-pnrenic nerve
665
What are the 5 special senses
Taste
Smell
Hearing
Balance
Sight/vision
666
The ear
External ear - collects sound wave vibrations and directs them to the eardrum
Middle ear - amplifies and transmits vibrations from eardrum to inner ear
Inner ear - contains the sensory receptors that convert the mechanical vibrations to nerve impulses, along with receptors for the equilibrium sense
667
The eye
Sits in the orbit of the skull which along with the zygomatic arch protects the eye.
Extraocular muscles allow the eye to move, they’re attached to the globe.
Meibomian glands secrete a waxy substance to prevent tears overflowing.
668
Gustation (taste)
Found on the dorsal surface of the tongue, epiglottis and soft palate.
They’re chemoreceptors stimulated by chemicals within food.
Papillae are small elevated structures on the tongue
Tate buds are made up of gustatory cells, sustentacular cells and hair like processes.
669
Olfaction (smell)
Receptors are in the nasal cavity.
Sniffing directs incoming air to the receptor sites, impulses are transmitted to the cerebrum in the olfactory nerve.
Animals can use pheromones to communicate with each other.
Jacobsons organ - present in cats, dogs, horses and snakes in the septum of their nose (roof of their mouth in cats). Its an extra sensory organ to detect chemicals,
670
Touch and pressure
Tactile sense = sensation of something being in contact with the surface of the body.
Pressure = sensation of something pressing on the body surface.
671
Touch
Different touch and pressure receptors produce sensations of light contact, deep pressure, vibration or hair movement.
Pain receptors - free nerve endings in the epidermis
Bulbous corpuscle endings - encapsulated nerve endings within the dermis detect heat and cold
Lamellar corpuscles - concentric layers of cells within the subcutis that respond to pressure
Meniscoid corpuscles - cup like discs in the dermis and epidermis that detect touch. Tactile hairs/vibrissae are sensitive to touch.
672
Pain
Widely distributed inside and on the surface of the body but not present in the brain.
Transduction - conversion of painful stimulus into nerve impulse
Transmission - conduction of nerve impulse to the spinal cord
Modulation - changes the sensory nerve impulse and can amplify or suppress sensory impulses
Perception - conscious awareness of painful stimuli
673
Proprioception
In the sense of body position and movement
Stretch receptors in skeletal muscles, tendons, ligaments and joint capsules sense movement of limbs, positions of joints, the state of contraction of muscles and the amount of tension being exerted on tendons and ligaments.
674
Avian bone structure
Long bones are hollow with a honeycomb structure
Larger bones are pneumatic - contain air sacs connecting to the respiratory system
Their keel is laterally flattened - increases surface area (only birds that fly)
Coracoid bone counteracts flight muscles and supports wings
No diaphragm
Lightweight beak and craniofacial hinge
Tibiotarsus and tarsometatarsus are fused
Bones of forelimb are adapted to reduce weight of the wing
675
Avian feathers
Develop from epithelial cells.
Made of keratin
Structure: central shaft or rachis filled with blood capillaries during growth. Vane with barbs interlocking barbules, they hook together to form a flat and wind resistant surface.
Feathers are constantly groomed to ‘zip up’ the barbules and apply secretions from the preen gland and waterproofing
Birds moult once a year - makes them vulnerable, happens after breeding season.
676
Avian feather types
Flight feather - long and rigid and found on the tail and wing
Contour or covert - cover the rest of wing and body, create a smooth outline. Shorter and flexible.
Filoplume and down - insulating layer, are close to the body, under the contour feathers. Designed to break up to absorb sweat and dirt keeping the bird clean.
677
Avian sight
Highly developed sense with large optic lobes.
Predator - forward facing, binocular vision, smaller visual field
Seed-eaters - laterally placed eyes, monocular vision, wide visual field.
678
Avian respiratory
No diaphragm - 1 body cavity called the coelum.
Lungs are fairly rigid and do not expand as they fill with air, instead there are free spaces within body cavities.
Cleft in the hard palate allows easier movement of air between the mouth and nasal cavity
Diving birds have no nares.
679
Avian breathing
Air enters choana and mouth
Glottis on floor of oral cavity
Larynx
Trachea
680
Avian digestive system
GI tract is suspended between wings within the body cavity to centralise weight.
No teeth to chew.
Oesophagus is thin walled and distensible to allow large pieces of food to pass.
Crop is a storage organ.
Stomach is divided into proventriculus and gizzard.
681
Avian urinary tract
Don’t have a bladder
Birds excrete nitrogenous waste from protein metabolism in the form of uric acid and urates.
Semi-solid urine is passed into cloaca where it mixes with faeces, enters rectum and more water is reabsorbed.
Faeces consists of; White urates, green/brown faces and clear urine.
682
Avian reproductive system
Female; left side is fully developed and right side is often vestigial. Ova develop within the ovary with an oocyte and yolk. An ovum is released every 24hrs until a ‘clutch is complete during the breeding season. Calcification of egg takes 15hrs.
Male; pair of testes cranial to the kidneys connected to the cloaca by the vas deferens. Size and weight of testes may increase at breeding season.
Cloaca contains rudimentary penis or phallus which engorges with lymph during mating. Semen is transferred into the everted female cloaca. Some species transfer sperm directly into the female cloaca.
683
What are the 2 orders of domestic reptiles ?
Chelonia; tortoises, terrapins and turtles
Squamata; lizards and snakes
684
What are the 2 orders of domestic reptiles ?
Chelonia; tortoises, terrapins and turtles
Squamata; lizards and snakes
685
Reptiles
Lizards; No sternum. Can shed their tail (autotomy). Their skin is thick/scaly/keritonised and sheds in pieces during ecdysis. They’re ectothermic. They have no pinna and the ear starts with the tympanic membrane (exposed). Lower eyelid is transparent. Have a Jacobsons organ. No diaphragm, rib movement is responsible for breathing. Heart has 3 chambers (right and left atria, 1 ventricle). Herbivores have a caecum, digestive tract has a cloaca. Have paired kidneys but the nephron has no loop of Henle.
Males have paired hemipenes but only 1 is used during mating, females have paired ovaries - the eggs are passed by the oviducts into the cloaca, eggs are oviparous.
Chelonians; shell has an upper carapace and a flat tended ventral plastron. Skeleton has adapted to hold the shell. Enlarged scales over forelimbs and spurs on their hind limbs. Paired nostrils and no hard palate. Have 2 lungs but no diaphragm. 3 chambered heart and renal portal system characteristic to reptiles. Have a horny beak and large fleshy tongues, oesophagus runs down left side of neck and enters the transverse stomach. Have paired kidneys and 2 ureters which empty into a urogenital sinus which also connects with bladder. Males have a large penis protruding from base of cloaca, females have paired ovaries, eggs are formed in layers. Males have longer tails and front claws than females.
Snakes; bones are loosely connected with the mandible joined by elastic ligament. Vertebrae varies from 150 to over 400 each has a pair of ribs fused to them. Have epidermal scales that very to position on body, they shed in one piece. Ears have no tympanic membrane and no middle ear. Paired nostrils which open into roof of their mouth. Have a reduced left lung or sometimes absent. Gaseous exchange only occurs in anterior lung. 3 chambered heart located one third of the way down the body. Carnivores and have 6 rows of undifferentiated teeth which are continuously replaced. Specialised glands to produce venom. Paired elongated kidneys with the caudal portions being the sexual segment in males. No bladder. Males hemipenes lie within the base of the tail. Slender females often only have 1 ovary and oviduct.
686
Define static balance
When an animal is standing still the head still makes minute movements.
Moves via sensory nerve VIII
687
Define dynamic balance
As the animal moves the endolymph in the semicircular canals moves and stimulates cristae within the ampullae.
Uses nerve VIII
