IBS (intro to body systems) Flashcards
1
Q
define autotrophs
A
Autotrophs are able to make their own food- All plants and some prokaryotes are autotrophic- photosynthesis
2
Q
define heterotrophs and the 3 types
A
Heterotrophs obtain organic (carbon-based) food which was originally synthesised by plants (Animals, Fungi, Some protists and prokaryotes)
-Holozoic nutrition:
- Solid or liquid food/organic material is taken in, broken down and absorbed
- Most animals
- Complex food taken into specialist digestive system.
-Saprotrophic nutrition
- live and feed off dead or decayed organic matter
- secrete enzymes which digest the food then absorb the soluble products- fungi
-Parasitic nutrition:
- Parasites
- Live on or in a host organism from which they obtain their food
3
Q
what are the 6 processes of digestion with brief descriptions
A
Ingestion – taking food into GI
Propulsion – moves food through alimentary canal
- swallowing,
- peristalsis
Mechanical breakdown
- mastication,
- churning,
- segmentation
- Increases surface area
Chemical digestion
- Enzyme secreted into lumen
Absorption
- Uptake of digested products
Egestion:
- Elimination of indigestible material from the body
4
Q
what are the sources and function of protein, carbs and lipids in the diet
A
Proteins –
source: Milk, eggs, meat, fish – complete Legumes, nuts, cereals – incomplete (low in one or more essential amino acids)
Function: Structural role- skin, hair, teeth, bone, muscle.
metabolic roles, enzymes, hormones, transport proteins
Lipids -
sources: Triglycerides animal products (saturated) Unsaturated in seeds , nuts olive oil, Cholesterol – egg, yolk, meats, dairy. ,
Function: Fatty adipose tissue (energy store), Insulation, Protection, phospholipids – cell membranes, Cholesterols – cell membranes, hormones
Carbohydrates
Sources: Mainly plants from plants, Simple sugars – from fruits, sugar cane, sugar beet, honey and milk, Complex carb – grains and veges
Function: energy source - glucose
Red blood cells and neurones.
The glycocarlyx
5
Q
name the vitamins needed, their sources and function
A
A- Retinol- Liver, milk, egg yolk, carotene- Formation of rhodopsin
B1- Thiamine- Cereal, brown rice, nuts and beans- TPP – coenzyme
B2- Riboflavin- Milk, eggs, yeast, liver, cereal- FAD – coenzyme in respiration
B3- Niacin- Nuts, meat and grain- Co-enzymes NAD, NADP
B5- Pantothenic acid- Most foods- Component of co-enzyme A
Vitamin C- Ascorbic acid Fresh fruit and vegetables- Electron carrier, collagen formation, utilisation of iron, stimulates immune system
D- Cholecalciferol- Synthesized in the skin, dairy products, oily fish, egg yolk- Calcium metabolism
E- Tocopherol- Vegetable oils, nuts, green leafy vegetables, and fortified cereals- Antioxidant, free radical scavenger, membrane integrity
K- Phylloquinone menaquinone- Green leafy vegetables- Blood clotting
Osteocalcin synthesis
6
Q
factors affecting energy requirements in animals
A
gender
- females need fewer calories than male animals because males generally have a higher metabolic rate
- Studies shows that neutered animals are twice as likely to become obese compared to intact dogs.
growing animals:
requires higher concentrations of protein (amino acids), calcium, phosphates, and energy in the diet to support basic physiological processes in addition to bone, connective tissue, muscle, and coat formation
pregnancy and lactation:
rely on forage and are only given concentrates during the last stages of pregnancy and early lactation.
Dairy cows need high levels of ME to sustain milk yields and so are fed concentrates to supplement forage
Small animals also have increased energy demands during late pregnancy and lactation, although cats show an increased intake from conception
Water is essential for all animals during lactation – thing that is often forgotten
Folic acid is especially important in the early stages as it’s crucial for development of the neural tube.
working animals:
Racehorses require a diet that is high in energy to fuel the levels of performance- require water
- supply of fast- and slow-release energy
- diets high in fat, protein, fibre and starch are appropriate for high-performance racehorses and they can obtain most of these nutritional elements from a combination of forage
7
Q
what are the 4 layers of the GIT and describe
A
The mucosa
- Epithelial layer, protective, cells have a short lifespan (2/3 days), secretions, absorption
- Connective tissue layer, blood vessels, nerves, lymph vessels
- Muscularis mucosae, thin smooth muscle layer
The Submucosa
- Connective tissue, blood vessels and nerves
Musculariz
- 2 layers of smooth muscle, inner circular and outer longitudinal
- Myenteric plexus: a network of neurons between the 2 layers
Serosa
- A thin layer of connective tissue
- Covered by the peritoneum (epithelial cells)
8
Q
describe the oesophagus
A
- Runs from pharynx to stomach. Role is to convey food to the stomach
- Cervical, thoracic and abdominal sections
- Muscularis – striated initially and then becomes smooth. Muscles needed for PERISTALSIS
- Mucosa – Stratified squamous epithelia for extra protection
- Sphincters at upper opening of oesophagus and at junction with stomach
- In many species, it enters stomach at sharp angle, aids function of lower sphincter and reduces vomiting (eg horses).
9
Q
describe peristalsis and the muscles involved
A
- The process by which food is moved along the oesophagus to the stomach
- During peristalsis, the circular and longitudinal muscles in the oesophagus contract and relax in a wave-like pattern to move food through the digestive tract:
- Circular muscles: These muscles squeeze and expand in a coordinated way to push food through the oesophagus.
- Longitudinal muscles: These muscles shorten the oesophagus and propel food forward
10
Q
describe the stomach and the types
A
- Chemical and mechanical digestion (to produce chyme)
- Stores food and to transfer stomach content to SI at a rate to ensure maximum digestive efficiency. (eg. Carnivores)
- Variation between species
- Monogastric
- Ruminants
11
Q
describe the mono gastric stomach
A
- Located behind diaphragm
- Sphincter prevents reflux
- 4 regions
- Cardia, small except in the pig where food is stored
- Fundus, stores food
- Corpus, mixing with gastric juice
- Pylorus, mixing, pyloric sphincter
- gastric glands on inner lining of stomach
12
Q
whats the role of gastric glands
A
- Mucus production for protection from digestive enzymes/acid
- Gastric juice is secreted by gastric glands
- Gastric juice contains
- HCl from parietal cells
- pepsin from chief cells
- contain endocrine cells, -produce gastrin, a hormone that stimulates the stomach to release acid
13
Q
describe the role of pepsin and HCL
A
- Pepsin is secreted from chief cells as the inactive enzyme precursor pepsinogen
- This prevents autodigestion
- Activated by HCl and pepsin itself in the lumen of the stomach
- Pepsin breaks down proteins into peptides and amino acids. It works with other enzymes, such as trypsin and chymotrypsin, to digest food
- HCL Secreted from parietal cells in the gastric gland
- Activates pepsinogen
- Provides optimum pH for pepsin activity
- causes pepsinogen to be cleaved into the active enzyme pepsin
14
Q
what are the 3 ways that gastric secretion is controlled
A
- Reflex due to sight and smell of food- The nerve impulses affect the epithelial cells directly and cause a release of gastrin
- Expansion of the stomach by the presence of food causes smooth muscle to contract. Secretion of gastrin into the bloodstream from special cells in the pyloric region of the stomach. The hormone stimulates the secretion of pepsin and HCl. It also stimulates muscular movement of the stomach
-
Control by peptides
- Peptide production
- G cell secrete more gastrin
- Parietal cells increases HCl production
15
Q
what are the 4 stoamchs of ruminants and their function
A
The Rumen: The rumen stores and ferments food. Salivary enzymes aid digestion, while muscular contractions churn the contents. It houses bacteria that produce cellulase, breaking down cellulose into beta-glucose, which is further fermented into volatile fatty acids (ethanoic, propionic, and butyric acids). These acids are absorbed through the rumen wall.
Reticulum: balls of cud formed and then regurgitated
The Omasum: Once food is liquid enough, it enters the omasum, a chamber with tissue folds that absorb water and concentrate the contents.
The Abomasum: The abomasum, or “true stomach,” produces hydrochloric acid and enzymes like pepsin, breaking down food before it enters the intestines.
16
Q
describe the tongue and its function in the oral cavity
A
- highly muscular organ
- surface covered in papillae,
- function of tongue- Prehension, Forming bolas, Pushing bolas back to oropharynx, taste, Grooming, Speech articulation
- function varies between species (taste buds, grooming, manipulate food)
17
Q
describe the role of salvilary glands in digestion
A
Salivary Glands:
Chemical digestion:
- Liquid – mixing food / formation of bolas
- Digestion
- Enzymes
- α-amylase - Amylase starts the digestion of starch (mostly)
- lysozyme - Lysozyme acts to cause lysis in bacteria.
18
Q
describe mastications role in digestion
A
chewing- mechanical digestion:
- Involves the actions of jaw, teeth, tongue and cheeks
Muscles of mastication – all of these raise the jaw
19
Q
describe how the size of the temporalis and masseter differ in different species
A
- Temporalis is larger in carnivores
- Carnivores and omnivores have mainly a vertical action for a cutting effect.
- Carnivores able to open mouth wide
- the jaw joint is on the smae plane as the teeth so tighter connection
- Masseter is larger in herbivores
- Herbivores also move jaw laterally which helps to grind food
20
Q
what is the function of cementum
A
the calcified or mineralized tissue layer covering the root of the tooth which sits inside the gum socket
21
Q
what is the function of dentine
A
hard dense bony tissue forming the bulk of a tooth, beneath the enamel
22
Q
what is the function of enamel
A
Tooth enamel is the hard, shiny, white outer layer of your teeth that covers the underlying tissues. The hardest substance in the body, stronger than bone – and is made up almost entirely of minerals.
23
Q
what is the function of tooth roots and the pulp cavity
A
Tooth Roots: Attach to the alveolar bone (mandible) via the periodontal ligament
Pulp Cavity: The area in between the tooth root that contains blood vessels and nerve endings
24
Q
what are the muscles involved in masticationa nd where are they.
A
- Temporalis: Top of head (O) → Coronoid pr of mandible
- Masseter: Zygomatic arch (O) → Ramus of mandible
- Pterygoid: sphenoid bone (O) → condylar pr of mandible
25
what are the 3 sections of the small intestine and describe them
- the duodenum
- the jejunum
- the ileum.
- The duodenum is the shortest part of the small intestine and the least mobile portion.
- Ducts from the pancreas and gall bladder enter the duodenum.
- The distinction between jejunum and ileum is arbitrary but the ileum is slightly shorter and more muscular.
- The jejunum and ileum are the greatly coiled part of the small intestine
26
describe the types of contractions in the small intestine
- Segmentation contractions
- Rhythmical mixing contractions
- Contraction of circular muscles
- Chops, **mixes** & rolls the chyme
- Peristaltic contractions
- Weaker
- **Moves**/propels the contents slowly along the small intestine
27
how does digestion happen in the small intestine
facilitated by enzymes secreted by:
- Pancreas
- Epithelial lining of duodenum
Also:
- Brunner’s glands secrete HCO3- nuetralises acid in chyme from stomach to ph6
- Pancreatic juice- contains bicarbonate + digestive enzymes
- Bile is produced in the liver but stored and concentrated in the gall bladder until needed.
28
what are the roles of endo and exopeptidase
**Endopeptidases**
- break the peptide links in the interior of the molecule
- e.g. pepsin (secreted by the stomach and acts within the stomach) and trypsin (secreted by pancreas – acts in the small intestine)
**Exopeptidases**
- break off terminal amino acids.
- e.g. carboxypeptidases (pancreas)
- e.g. aminopeptidases (epithelial cells)
29
whats the role of trypsinogen in digestion
Trypsinogen us scereted by pancreas in an inactive form- trypsinogen- when it reaches where it needs to be it becomes trypsin via enzyme enterokinase where its used in endopeptidase. Then its converted to chymoytrypsin- involved in the activation of exopeptidases
30
whats the role of the ileum
digests
- Vitamin B12
- Bile salts
- Nutrients not absorbed by duodenum and jejunum
31
describe the caecum
Caecum:
Located at the junction of the small and large intestine - Ileo-caecal junction
- receives material from the ileum
- absorbs some of the fluid and salts
- mixes the contents with mucus
32
whats the role of the large intestine and how does it do this
Functions:
- Recovery of water
- Storage of waste
- Microbial digestion for herbivores (caecum)
Faeces moves along the colon by peristalsis, water is reabsorbed and they become more solid. The movement is relatively slow and it can take up to 24 hours for material to travel the length of the organ
33
describe the hormone Cholecystokinin (CCK)- when is it released, where, what does it do
When: When amino acid and Fatty acids reach the duodenum
where: Duodenal epithelial cells
what: Stimulates the release of digestive secretions from the pancreas and gallbladder and slows gastric emptying – aids absorption
34
describe the hormone Secretin- when is it released, where, what does it do
When: Acidic conditions
where: Duodenal epithelial cells
what: Stimulates the pancreas to release sodium bicarbonate which neutralises acidic chyme and reduces gastric acid secretion
35
describe the hormone Gastrin- when is it released, where, what does it do
when: many stimuli including stomach distension and vagal nerve stimulation
Where: Stomach
what: Stimulates the production of gastric juices (HCl and pepsinogen) and increases gastric motility
36
describe the hormone Enterogasterone- when is it released, where, what does it do
when: When fatty acids or excess acids enter duodenum
where: Duodenal epithelial cells
what: Inhibits peristalsis and acid secretion by the stomach – aids absorption and slows progress of chyme through the intestines
37
describe the 4 ruminant stomachs
- Rumen**-**
- Largest of the 4 compartments – almost fills entire **left** side of abdominal cavity
- Huge fermentation chamber
- Contains many microorganisms (bacteria, protozoa, fungi)
- These supply enzymes to break down fibre etc in the food
- Reticulum-
- 2nd chamber
- Honeycomb structure
- Food freely passes between here and the rumen
- Lies against the diaphram (and near to heart)
- Any swallowed foreign object (wire, nails etc) tend to lodge in the reticulum
- Omasum
- Muscular spherical organ
- Located to the right of the rumen and reticulum
- Internal structure has broad longitudinal folds like leaves of a book
- Involved in the **grinding** and **squeezing** of digesta and also **absorption** of water and VFAs
- Abomasum
- The ruminant **true or glandular** stomach
- Located on the right side of the rumen
- Very similar to the stomach of non-ruminants
- Secretes acids and enzymes
- Prepares food for further chemical digestion and absorption along the small intestine.
38
describe the digestive system of hindgut fermenters and some problems associated with them
- Horses, rabbits, rhinos, rodents
- Relatively simple stomach but larger caecum and colon where microbes are found
- Considerable fermentation occurs
problems:
- horses
- Caecum projects from side of gut
- Small intestine empties directly into the caecum
- Reverse peristaltic movements allows food to pass from caecum back into small intestine
- rabbit
- Behaviour known as **caecotrophy**
- Ingestion of soft faeces (caecotrophs) originatingfrom the caecum
- Caecotrophs usually produced when animal is at rest
- Contain bacteria, yeasts, fermentation products (source of nutrients esp. protein)
39
describe the size of Large intestine based on diet an stomach
- Carnivores:
–little microbial fermentation,
–small LI
- Pigs and ruminants:
– intermediate sized coiled LI
- Rodents and horses:
–large LI for microbial fermentation
40
describe the avian digestive system
- **Beak** replaces lips and cheeks (no teeth)
- **Crop**
–Storage of food,
–some digestion
- **Proventriculus**
–Glandular stomach
–acid secretion
- **Gizzard**
–Muscular organ (grinds food)
- **Two** **caeca** (absorption, some fermentation)
- **Cloaca**
–Faeces and urine excreted together
41
where is the pancreas found
small, lies below stomach
42
endocrine and exocrine function of pancreas
Endocrine function
- Produces hormones: insulin and glucagon
- Produced in α and β cells in the islets of Langerhans
Exocrine function
- Produces digestive enzymes secreted into the pancreatic duct
- Produced in acini – groups of epithelial cells which secrete pancreatic juice into a lumen
43
whats the function of liver
- production of cholectserol/bile
- synthesis of clotting factors
- protein/lipid/carbohydrate metabolism
- detoxification
- stoarge of vitamins/cholesterol
44
structure of liver
- Located behind the diaphragm
- 2-4 main lobes
- Gall bladder not present in the horse
- recieves both arterial and venous blood
45
Describe the production, and makeup of bile.
Bile Production:
- Most cholesterol produced in the liver is used to make bile
- Synthesised in hepatocytes
- Secreted into channels between hepatocytes…bile canaliculi
- Drains into bile duct where it may be secreted into the intestine or stored in the gall bladder first
Made up of: water, bile salts, cholesterol, bilirubin, bicarbonate ions.
recirculation
46
whats the role of the liver in carb metabolism
- Liver metabolises carbohydrates in response to insulin, glucagon and adrenaline (glycogenesis& glycogenolysis)
- Liver stores glycogen
- insulin turns glucose into glycogen and glucagon turns glycogen into glucose
47
whats the role of the liver in the production of glucose from amino acids
Gluconeogenesis-
- Occurs when blood glucose concentration falls. In response to glucagon when glycogen stores decline e.g. when fasting
- Making additional **glucose** from **non-carbohydrate sources**
- mainly amino acids, lactate and glycerol
- Pyruvate is formed from their breakdown
- Pyruvate can then be used to generate glucose
- Many of the reactions are the reverse steps of glycolysis
- Inhibited by insulin
48
what is transamination
- amine group removed and added to another amino acid
- the conversion of one amino acid to another
- Non-essential amino acids can be synthesized by transamination to make up for deficiencies in the diet
49
what is deamination
amine group removed → organic keto acid (and ammonia)
50
describe urea formation
- Ammonia is converted to urea in the ornithine cycle in the hepatocytes
- Urea is then transported to the kidneys in the blood where it is excreted.
51
describe the roles of fibrinogen, globulins and albumin
- many globular proteins are synthesised in the liver
- Plasma proteins help to transport other substances in the blood e.g. thyroxine
- Fibrinogens are important proteins in coagulation of blood
- Albumin, prevents too much water loss into the tissue fluid, it helps regulate osmotic pressure of blood
52
whats the role of the liver in detoxification
- Occurs mainly in the SER of the hepatocytes
- Toxins are either converted into a harmless product or excreted in the bile Eg ethanol C2H5OH
- ethanol -> ethanal -> acetate, alcohol dehydrogenase
53
what are the causes, effects and treatments of liver disease in domestic species.
Cause: congenital, hepatotoxins, infection, inflammation, obesity,
Clinical signs:
- Nausea, diarrhoea, Weight loss, Neurological signs due to build up of toxic substances eg urea, Jaundice, build up of bilirubin
Treatment:
The goals of treating liver disease are to eliminate harmful toxins promote healing and regeneration of liver tissue, prevent or control complications of liver dysfunction and treat the underlying cause where possible
54
when is an animal classed as obese
- 15-20% overweight
- BCS of 5 or 8/9
55
how do you measure obesity
1. Weight
- RBW= current weight/ optimal
2. Body mass index
- BMI = body mass (kg)/height (m2)
3. Percentage fat
- Around 15 – 20% is optimal in animals
4. Morphometric analysis
- In animals the pelvic circumference may be used as it changes most with increasing or decreasing weight
5. Body condition score
- Commonly based on a 5-point or a 9-point scale
- Can be subjective…
56
whats the consequences of obesity
- dystocia- diffeculty birthing
- difficulty breathing
- reduced life expectancy
- diabetes
- CV disease
- joint problems
- increased risk under anaesthetic
57
what are the risk factors of obesity
- gender
- neutering
- activity
- age
- genetic
- owner perception
- human-animal bond
58
what are the ways of controlling
- A specific weight-reducing food might be recommended
- Many of these diets contain a high fibre content which dilutes calories and reduces overall consumption
- decrease calorie intake → increase exercise→ re-assessment
- set a goal and time scale
59
what are the different types of joints in the skeleton and describe
- **Fibrous joints / Synarthrosis – immovable joint**
- Fibrous connective tissue joins bones
- Little movement -frowth/blows to the face
- Flat bones of the cranium
- **Cartilaginous joints / Amphiarthrosis – slightly movable**
- Joined by cartilage, allows some movement
- Joints between vertebrae in the spine
- **Synovial joints / Diarthrosis – fully articulated**
- Allow large movement between bones
60
what are the diseases associated with cartilage, tendon, ligament, capsules and their characteristics
Cartilage- Osteoarthritis- This is the most common type of arthritis, characterized by the breakdown of articular cartilage. As the cartilage wears away, bones rub together, causing pain, stiffness, and inflammation.
tendon- Tendonitis- Inflammation of a tendon, often caused by overuse or repetitive motions. It can lead to pain, stiffness, and difficulty moving the joint
ligament- Ligament Sprains- Stretching or tearing of ligaments, resulting in pain, instability, and swelling.
capsule- Rheumatoid Arthritis- An autoimmune disease that causes synovial membrane inflammation. This inflammation can damage cartilage, bone, and other joint tissues.
61
what are the types of synovial joints
a- Ball and socket - shoulder/hips
b- Hinge- limbs
c- Plane/gliding - tarsal + carpal
62
define class 1, 2 and 3 levers
A class 1 lever puts the pivot between the effort and the load forces.- force multiplier
A class 2 lever puts the load between the pivot and the effort force.- force multiplier
A class 3 lever puts the effort force between the load and the pivot- distance multiplier + speed
63
Give examples of class 1 and class 3 levers
1- ear- better hearing
3- shoulder (all limbs)- speed
64
defien antagonistic muscles and five an example
- Muscles are arranged in groups so that they pull in opposite direction- Known as **antagonistic pairs**
- biceps- flexers
- triceps- extender
65
whats the equation for moment (Nm)
force x distance
66
whats the function of the nervous system
- Receive stimuli from external and internal environments
- Conduct impulses and coordinate an appropriate response
- Integrate activities of other systems
67
what are the types of NS and their components
- Central NS: Brain, Spinal cord
- Peripheral NS: Sense organs, Peripheral Nerves
68
how does the nervous system respond to stimuli
1. Reception – **sensory receptors** in the sense organs detect stimuli (change in internal/external environment) and initiate an electrical impulse (action potential)
2. Transmission – of electrical impulse from neurone to neurone to the CNS
3. Integration – sorting and interpreting signals
4. Action – by an effector (muscle or gland)
69
how is the CNS protected
protection via
- Skull – bone- hard protection (brain)
- Vertebrae bone- hard protection (spinal cord)
- Meninges – 3 layers of membrane (dura- hard, arachnoid- weblike, pia- delicate)
- CSF – Cerebrospinal fluid shock absorbing fluid (also acts as medium for exchange for nutrients, etc, between blood and brain)
70
whats the role of the brain and spinal cord in the CNS
**Brain**:
- Receiving impulses from sensory receptors
- Integrating & correlating incoming info
- Sending impulses to effector organs
**Spinal cord**
- Transmit impulses to and from brain
- Relay action potentials between sensory organs & effector organs (in reflex actions)
71
describe the Peripheral NS and its divisions
Includes paired spinal nerves and cranial nerves
Can be divided into:
- **Somatic nervous system**
- **Autonomic nervous system**
- Peripheral nerves consist of bundles of axons of sensory and motor neurones (nerve fibres) surrounded by connective tissue and glial cells
- Afferent (sensory) nerve fibres transmit signals towards the CNS
- Efferent (motor) nerve fibres transmit signals away from the CNS (eff off)
- Both somatic and autonomic nervous systems have afferent and efferent pathways
72
describe the somatic nervous system
- eacting to external environment/stimuli
- Under conscious/voluntary control
- Detect change using sense organs
- Sensory neurone relays information from sensory receptor to CNS
- Motor neurone relays message from CNS to effector i.e. skeletal muscle
73
describe the autonomic nervous system and its pathways
nvoluntary response to internal stimuli. E.g. heart rate, vasoconstriction/dilation, breathing, digestion etc.
efferent pathway consists of
- sympathetic nervous system
- “Fight or flight”
- Mobilise energy
- E.g. increased heart rate, increased heart force, reduced digestion
- parasympathetic nervous system
- “Rest and digest”
- Activated when at rest – recuperation after stress response
- Conserve or restore energy
E.g. reduced heart rate, increased digestion
74
what are the types of neurones
- Sensory neurone
- Collects sensory information
- Transfers information to the CNS
- Motor neurone
- Transfers nerve impulse from CNS to muscles
- relay neurone
- Connect one neurone to another
- Found in CNS
75
whata are some examples of sensory neurones, their sense, location and the energy received
Photorecepotors- sight- eye- light
Chemoreceptors- taste/smell- mouth/noes- chemical potential
Mechanoreceptors- touch/hearing- skin/ear- kinetic
76
whats the differenvce between innate and conditioned reflexes + e.gs
innate- withdrawal reflex- response to pain
conditioned- scratching reflex-
- A dog will scratch rhythmically with one hind-leg in response to an irritant stimulus
77
describe the steps to generating an action potential
- Begins at Resting potential (-70mV)
- **Depolarisation**, Na+ voltage gated channels open rapidly- potential difference increases (outide becomes more positive than inside), if enough positive charge enters, then we might pass a threshold (-55mV)- triggers AP
- **Repolarisation,** Na+ channels close and Potassium channels open, K+ moves in, reducing potential differece
- **Hyperpolarisation**, more K+ leaves than Na+ enters - -90mV
- **Refractory period-** after hyperpolaristaion, potential diff returns to resting, at this point, Na+ is inside and K= is outside and this must be returned to normal to generate another action potential
78
how is resting potentila established and maintained
-70mv
- The Na+/K+ pump pumps 3 Na+ out and 2K+ in. Most of the K+ is found inside the cell and most Na+ is inside
- But K+ will also leak out of the cell via facilitaed diffusion as the membrane is more permeable to K+ (there are more K+ channels in the membrane than Na+).
- As the K+ leaks out it causes the membrane to polarise. It will be become more negative inside the cell compared to outside.
79
why is the refractory period important
- Ensures unidirectional propagation
- Prevents overfiring of action potentials- no excessive nuerone activity-normal brain function and preventing seizures.
- encoding information, shorter refractory period allows a neuron to fire more rapidly, which may be important for encoding high-frequency signals. Conversely, a longer refractory period may be important for encoding lower-frequency signals.
80
what is the all or noting response
**The size of the impulse is independent of the size of the stimulus**:
If the intensity of a stimulus is below the threshold potential, no action potential will be initiated. aph
But If it is above **threshold** then an AP will happen. The intensity of the stimulus is coded by the frequency of APs.
81
what are the factors that affect speed of a nerve impulse
- myelination
- axon diameter
- temperature
82
how does myleination increase speed of an imopulse across the axon
- Ion channels present at the nodes of Ranvier allow the movement of sodium and potassium ions across the membrane. It is at these points that an action potential can be generated in a myelinated neurone.
- The action potential moves from node to node. This is referred to as **saltatory conduction** and is much quicker than the step-by-step conduction that occurs in a non-myelinated neurone.
83
how does axon diameter affect the speed of nerve impulses
Action potentials are conducted quicker along axons with bigger because there is less resistance to the flow of ions than in cytoplasm of a smaller axon. With less resistance the ions diffuse faster and propagation at next part of neurone is quicker.
84
how does temperature affect the speed of nerve impulses
the speed of conduction increases as the temperature increases. Ions move faster (greater kinetic energy) as the temperature rises . But if the temperature gets higher than 40C than proteins would start to denature
85
what is hypokalaemia
- Hypokalaemia- too little potassium
- Hypokalemia increases the resting potential (i.e., makes it more negative) and hyperpolarizes the cell
- induce dangerous **arrhythmias.**
86
what the role of synapses
- ensures one way transmission
- increases the range of responses to a stimulus
- summation
87
whats the cause, mechanism, clinical signs and treatment of Botulism toxin
Cause:
- Caused by the bacteria Clostridium botulinum
- Anaerobic bacteria found in the soil
- Toxin ingested in contaminated feed: canned food, silage
Mechanism:
- The toxin acts at the presynaptic membrane and prevents ACh release
Clinical signs:
-Ruminants particularly susceptible, dead birds /rodents are usually the source.
- Progressive flaccid paralysis
- Muscular weakness
- Sternal recumbency
- Loss of tone in tail
- Protruding tongue
- Laboured breathing
- Post mortem, presence of bacteria or toxin in Gastrointestinal tract (GIT)
Treatment;
- Supportive: fluids, feeding, turning
- Antitoxin: expensive, efficacy
- Antibiotics – not effective
- Euthanasia due to welfare issues
Prevention
- vaccine not generally available yet in the UK – only used under special treatment certification
- Feed analysis – food borne
88
whats the causes, mechanisms, effexts and treatment of organophosphate
Causes:
- Insecticide drugs eg. diazinon
- Sheep dips, flea and mange treatments
Mechanism:
- AChE (competitive) inhibitors which leads to increased ACh in the synapse and muscles
- acts as a non-competitive inhibitor to Acetylcholinesterase so Ach is not broken down
Effects:
Rare in small mammals
- Headaches
- Tiredness
- Muscle aches
- Anxiety, changes in personality
- MCS
- Large doses: collapse, respiratory distress, dysrhythmia
Treatment:
- Prevent further exposure
- Supportive
- Atropine
- Pralidoxime chloride
89
define cataract
A cataract is an opacity of the lens or its capsule and often gives the eye a cloudy appearance
90
define glaucoma
if drainage of aqueous humor is impaired the pressure in the eyeball is increased- bulges, a condition known as glaucoma
- Aqueous humor supplies the avascular cornea and lens with nutrients and removes waste
- It also helps the eyeball to maintain shape
91
wha are the causes and treatment of cataracts
Causes- diabeteic dogs, age,
Treatment- can only be treated by surgery, phacoemulsification removes material from inside the lens, small corneal incisions remove the cataractous lens through a small opening created, and high-frequency ultrasonic waves are used to carefully break the cataract into small fragments which are then removed by means of irrigation
92
causes and treatments of glaucoma
causes- family history, age, ocular hypertension
treatment- prescription eye drops, laser treatment, lowers ye pressure fluid drains, surgery
93
whats the vestibular system - ear
- controls balance and tries to prevent an animal falling over.
- the balance system consists of sensors (located deep inside the ear in the inner ear) and a specialised control centre (located at the back of the brain)
94
whats the anatomy and role of of the semicircular canals
- Each semi-circular canal has one bulbous shaped end called an ampulla and is filled with fluid called endolymph
- - In the ampulla is a structure that is called the **gel-cupula.**
- There are multiple sensory hairs cells projecting into the gel of the cupula (the stereocilia)
- When the head changes position fluid in the canal pushes the cupula, bending it. This causes the hair cells to bend and creates APs
95
how does rotational movement work in the ear
- head changes positon so the endolymph flows against the movement- inertia
- The cupula gets pushed or pulled during angular movement from the flow of endolymph, causing the cupula to bend. Sensation triggered
96
what are the steps to depolarisation of the hair cells in ear- signal transduction
1. The surrounding extracellular fluid, the **endolymph** has a **high concentration of K+.** This is not like other parts of nervous system where the concentration K+ outside the cell is lower.
2. The depolarisation is brough about by bending of the hair cell, which opens **mechanically-gated** K+ channels.
3. The K+ **influx** depolarises the cell.
4. As this occurs **voltage gated Ca2+ channels** open.
5. Results in exocytosis of the neurotransmitter **glutamate**.
- Glutamate creates excitatory post synaptic potentials in sensory neurone which opens sofium gated channels and Impulse travels along nerve fibres that form the auditory nerve
97
what are the 2 otolithic organs in the ear and describe them
- the utricle and saccule.
Utricle (horizontal): If we start moving forward the inertia dense otoliths will bend the hair cells backwards. This creates an impulse telling us forward acceleration
Saccule (vertical): If we were in a lift and the lift starts moving up. The inertia of the otoliths pulls bends the hair cells downwards. This creates an impulse telling us about acceleration in the vertical plane.
98
whats the role and anatomy of the otoliths
- on top of the gel are sprinkles of “ear stones” like sprinkles on ice cream. These are **otoliths** … ear rocks. (CaCO3).
- Both utricle and saccule detects acceleration and motion and transmit this information to the brain via the **vestibulocochlear nerve**. then move the oppositw way of movement
99
whats the role of the outer ear
- From pinna to tympanic membrane (ear drum)
- The pinna, the visible part of the ear, is shaped like a funnel. This structure helps to collect sound waves from the environment and direct them into the ear canal.
100
whats the role of the middle ear
needs sound amplification
- sound collected by pinna>ear canal
- Sound waves cause pressure change as oval window is much smaller than the tympanic cavity
Amplification achieved
1. Surface Area Difference: Ear drum has an area of 0.6cm2. The oval window is much smaller , about 0.032cm2. Reducing the area increases pressure exerted on the window
2. The Mechanical advantage of the bones These bones act as a Type 1 lever system, transferring vibrations from the eardrum (tympanic membrane) to the oval window (the membrane-covered opening to the cochlea). The lever action increases the force of the vibrations while maintaining their frequency.
101
whats the role of the inner ear
- the middle of the cochlear contains the basilar membrane
- It vibrates in response to sound, with different regions tuned to specific frequencies (high frequencies near the base, low frequencies near the apex).
1. Stapes foot transmits pressure waves to perilymph
2. Causes the basilar membrane to bend.
3. The basilar membrane will bend most at the place that the vibration has the greatest resonance.
4. Low frequency sounds bend the basilar membrane at the apex
5. High frequency sounds bend the membrane closer to the start
102
how many motor nuerones dles somatic nervous system have compared to automatic
Somatic has 1 motor nuerone and myleinated
autonomic has 2 motor nuerones and is not myleinated
103
how is the sympathetic system organised
- Ganglions located just outside the CNS
- Ganglia in a chain each side of spinal cord.
- Sympathetic chain ganglia
- Short pre-ganglionic nerve fibres
- Synapse with many post-ganglionic fibres
- In a number of ganglia
- (or synapse with prevertebral ganglia...or direct innervation of adrenal medulla)
- Endocrine association
104
how is the parasympathetic system organised
- Pre-ganglionic fibres are LONG
- Ganglia are in target organs/adjacent to the wall
- Ganglia NOT inter-connected
- No endocrine association
- Action more localised than sympathetic system
- Post ganglionic synapses use acetyl choline as neurotransmitter
105
name the nerve fibre, its nuerotransmitter and its desigmation
Pre-G SNS - Acetylcholine- Cholinergic
Post-G SNS- Noradrenaline
(Norepinephrine)- Adrenergic
Adrenal medulla- Adrenaline (Epinephrine)- Adrenergic
Pre-G PSNS- Acetylcholine- Cholinergic
Post-G PSNS- Acetylcholine- Cholinergic
106
What is the role of the autonomic nervous system in animals
Maintenance of homeostasis
- Blood pressure control
- Body temperature
- Internal pH
- Blood oxygen and carbon dioxide
- Work through negative feedback mechanisms
107
whats the function of the cornea
transparent lens that refracts light as it enters the eye
108
whats the function of the iris
controls how much light enters the eye
109
lens function
transparant disc that can change shape to focus light on the retina
110
retina function
contains light receptor cells - rods and cones
111
optic nerve function
sensory nuerone carries impulse from eye to brain
112
describe binocular and monocular vision
- **Binocular** (stereoscopic) vision occurs when both eyes are used to view the same object
- Better detail and depth perception
- Image appears three-dimensional
- Predator species
- **Monocular** vision refers to animals which use each eye independently
- Birds and lizards
- Greater field of vision
- some animals use both, eg horses
113
describe the effect on the pupil in dim and bright lighting
DIM: pupil dilates, circular muscles relax, radial muscles contract and its controlled by SNS
BRIGHT: pupil constricts, circular muscles contract, radial muscles relax, controlled by PSNS
114
how does the lens help to focus light rays on the fovea
refraction-As light moves from one medium to another its speed and therefore direction changes
- the lenses concave shape allows for refreaction to occur and make one focal point
115
what does refraction depend on
- the distance of the light source from the eye
- curvature of the lens
116
what does accomodation mean in relation to focusing the eye
Accomodation
- the eye can alter its focus to form clear images of both close and distant objects on the retina
- Achieves this by altering the shape of the lens
- Lens shape can be altered by suspensory ligaments and the ciliary muscles.
- This adjusts the focus of the image on the back of the retina
117
how does accomodation enable animals to focus on distant objects
**Distant**
- Ciliary body relaxed
- Suspensory ligaments taught
- Lens under tension
- Lens flatter
118
how does accomodation enable animals to focus on near object
- Ciliary body contracted
- Suspensory ligaments relaxed
- Lens free to take its own shape
- Fatter lens
119
whats the pathway ofrods and cones to the brain
- Rods and cones generate a neural signal
- Rods and cones both form synapses with bipolar cells
- Bipolar cells in turn synapse with sensory neurons called ganglion cells.
- The axons of the ganglion cells cover the inner surface of the retina - combine to form the optic nerve
120
whats the distribution of rods and cones
- There are no sensory cells where the optic nerve leaves the eye…blindspot
- Rods and cones are unevenly distributed
- **Area centralis:** Region where the concentration of sensory cells are highest, especially cones.
- **Fovea***…*in middle of area centralis with highest density of cones. In humans it contains only cones.
121
describe cone cells
- Respond to light at higher intensities so less sensitive
- Allow perception of fine detail
- Colour vision as have varying sensitivity to light of different wavelengths
- Each cone synapses to one bipolar cell which in turn synapses to one ganglion cell – so each has its own pathway to the CNS- **spatial** **summation**
122
describe rod cells
- Function in dim light (scoptic vision) as very sensitive
- Allow detection of shape and movement
- Not colour sensitive
- many rods make synapse with one bipolar neuron - **temporal**
123
what does rhodopsin consist of
- **opsin**: a protein
- **retinal**: a reversibly bound cofactor produced in cells from Vitamin A
124
describe retinal
- **Retinal is key to the light reaction** and the initiation of the nerve impulse.
- All **photopigments contain retinal** (differences in properties of photopigments due to variation in opsin)
- Retinal is a long molecule
125
describe the process of bleaching in retinal
- When it is bound to opsin it has an angular (folded) shape (***cis-*configuration**)
- When retinal absorbs light, it straightens due to change in the bonding (to the ***trans-*configuration**) and no longer fits into the opsin molecule (becomes cleaved)
- process is called bleaching
126
describe the process of bleaching in rhodopsin when here is a light stimulus vs when there isnt
**When there is light stimulus**
- Rhodopsin molecules absorb light, change conformation and retinal separates from opsin (a process known as bleaching)
- Once cleaved it cannot continue to absorb more light
- In bright light most rhodopsin molecules are bleached
**When there is no light stimulus**
- Enzymes convert retinal back to *cis* form
- Retinal can then recombine with opsin to make rhodopsin
- This is called dark adaptation
- requires more time than bleaching
- this explains why you are initially ‘blind’ when you walk from bright sunlight into a darkened room
127
describe visual acuity and how it comes about
*The ability of the eye to resolve two or more points that are separated spatially*
- Cones are responsible for high visual acuity
- each cone synapses to one bipolar cell which in turn synapses to one ganglion cell – so each has its own pathway to the CNS
- Each part of an image is detected by a different cone cell
- This acuity would be lost if more than one cone was to share the same sensory pathway- convergence
- Fove ha most cone cells (**FO**r **VE**ry **A**cute Vision)
128
describe colour vision and how it comes about
- There is only one type of rod
- rods are unable to provide information about the wavelength of light that stimulates the retina
- There are functionally different types of cone cell, all contain photo pigment… photopsin
- each has a different form of **opsin**
- they have sensitivity to light of different wavelengths.
- Humans have three different types of cone
- a specific wavelength of light will lead to a given *ratio* of the degree of stimulation of blue, green and red cones.
- By comparing the stimulation of different types of cone, the human brain can detect a wide range of colour
129
