Microanatomy Flashcards
1
Q
Definition of a tissue
A
Collection of cells specialised to perform a particular function
2
Q
What are the four types of tissue and what are their general functions
A
Epithelium - lining and covering
Connective tissue - support and protection
Nerve - fast communication
Muscle - movement
3
Q
What is an organ
A
Part of the body that is more than one tissue that forms a structural unit responsible for a particular function
4
Q
Describe the structure of the cell membrane
A
Phospholipid bilayer
Contains embedded membrane proteins but also peripheral membrane proteins
Fluid mosaic model
5
Q
Label the diagram of cell membrane
A
See lecture “cells 1”
Slide 11
6
Q
What is the function of cholesterol in the cell membrane
A
Maintains fluidity in all temperatures
7
Q
What is a glycoprotein
A
Protein with carbohydrate attatched
8
Q
What is a glycolipid
A
Lipid with carbohydrate attatched
9
Q
What are the functions of the cell membrane
A
- structural support
- compartmentalisation - special activities are contained and independently regulated
- selectively permeable membrane - regulates passage of specific solutes
- signal transduction - responds to and transmits stimuli
- intercellular interaction - allows cells to recognise and signal each other - cell adherence - regulates entry and exit of molecules
10
Q
What does compartmentalisation mean in terms of the cell membrane
A
Specialised activities are contained and independently regulated
11
Q
What does signal transduction mean in terms of a cell membrane
A
Responds to and transmits stimuli
12
Q
What does intercellular interaction mean in terms of cell membrane
A
Allows cells to recognise and signal each other
Cell adherence
Regulates entry and exit of molecules
13
Q
Is surface if the membrane hydrophilic or hydrophobic. Why?
A
Hydrophilic because the surfaces are formed by the polar head groups of the lipid molecules
14
Q
Is the inner portion of the cell membrane hydrophilic or hydrophobic? Why?
A
Hydrophobic because the fatty acids of the lipid molecules face each other
15
Q
What are three types of lipids found in the cell membrane
A
Phospholipids, cholesterol and sphingolipid (nervous tissue)
16
Q
What are the four types of proteins found in cell membranes
A
Transporters
Anchors
Receptors
Enzymes
17
Q
What is the role of transporters in the cell membrane
A
Allow passage of small ions, molecules and water in either direction
Gap junction
18
Q
What is the role of anchors in the cell membrane
A
Anchor the intercellular cytoskeleton to the extracellular matrix (ECM)
19
Q
What are is function of receptors in the cell membrane
A
Allow recognition and localised binding of molecules
20
Q
What is the main role of the nucleus
A
To duplicate genetic information
Transcribes information necessary for synthetic processes
21
Q
What is chromatin
A
Highly folded nucleoprotein complex that consists of DNA and structural proteins histones
22
Q
What does a) heterochromatin indicate and what does b) euchromatin indicate
A
a) indicates cell is metabolically inactive
b) indicates active chromatin
23
Q
How does heterochromatin and euchromatin appear in an electron microscope
A
Heterochromatin appears as dense staining and highly condensed
Euchromatin appears as lightly-staining/ electron-lucid
24
Q
What happens in the nucleolus
A
Site of ribosomal RNA synthesis and initial ribosomal assembly
25
Describe the nuclear envelope
Double membrane with a perinuclear space
Continuous with rER
Inner membrane supported by nuclear lamina
Pores
26
Label the diagram of the nuclear envelope
See lecture 1 slide 19
27
Describe the nuclear pore complex (NPC)
Formed by the merging of inner and outer membranes
28
What is the role of nuclear pores
Mediate the active transport if proteins, ribonucleoproteins and RNAs between nucleus and cytoplasm
29
What has an impact on how many nuclear pores there are
More active the nucleus is in transcription then the greater number of pores
30
What is the function of the nuclear lamina
Supports nuclear envelope
Essential in DNA replication, transcription and gene regulation
Anchors heterochromatin
Important in spatial organisation of nuclear pore
31
What is the enzyme that generates ATP in the matrix of the mitochondria
ATP synthase
32
What is the purpose of Cristae in the mitochondria
Increase surface area
33
Label the mitochondria diagram see lecture 1 slide 22
Labelled
34
What other tasks are mitochondria involved in other than production of ATP
Cell signalling
Cellular differentiation
Cell death (apoptosis)
Maintains control of the cell and cell growth
35
Describe the structure of ER
Membrane continuous with nuclear envelope
| Consists of flattened sacs (cisternae) and tubules with a fluid-filled lumen
36
What is the difference between Rough ER and smooth ER
Rough has ribosomes located in membrane + more flattened in appearance
Smooth has none + more tubular in appearance
37
What is the function of smooth ER
Synthesises lipids
In striated muscle it is used as a calcium store
Enzymes within SER can help eliminate toxins, drugs, alcohol - prominent in hepatocytes (liver drugs to break down alcohol)
Carbohydrate metabolism - break down glucose to glycogen
38
What is the function of rough ER
Synthesis of secretory proteins and membrane proteins
Polypeptides assembled on the bound ribosomes and threaded into the ER lumen
Addition of carbohydrates to proteins
Folding of polypeptide chain - occurs in ER lumen
Quality control
39
What is the describe and state the function of free and fixed ribosomes
Free: scattered throughout the cytoplasm; assemble proteins for internal use
Fixed: fixed to RER; assemble proteins for export
40
Describe the structure of Golgi apparatus
A stack of flattened membranous sacs called cisternae
41
Functions of the Golgi apparatus
Modify products of the ER - glycosylation
Storage
Sorting and packaging of molecules into vesicles for transport
Shipping of secretory vesicles
42
In which direction through the Golgi apparatus does membrane modification occur
Cis to trans
43
In the Golgi apparatus which is the receiving face and which is the shipping face
```
Cis = receiving
Trans = shipping
```
44
Describe lysosomes
Membranous sacs/vesicles containing hydrolytic enzymes
| Involved in autophagy and heterophagy
45
What does autophagy mean
Destroy and recycle organelles and macromolecules from within the cell
46
What is heterophagy
Destroy material and extracellular matter that has been phagocytosed/ endocytosed by the cell
47
What is the difference between primary and secondary lysosomes
Primary: those which have yet to begin a digestive event - fuse with a phagosome
Secondary: where digestion proceeds
48
What is the name of the membrane bound vesicle that contains undigested material after lysosome action
Residual body
49
What are the seven steps of heterophagy
1. Chemotaxis and adherence of microbe to phagocyte
2. Ingestion of microbe by phagocyte
3. Formation of phagosome
4. Fusion of phagosome with a lysosome to form a phagolysosome
5. Digestion of ingested microbe by enzymes
6. Formation of residual body containing indigestible material
7. Discharge of waste materials
50
Describe autophagy
1. Phagophore formed - encloses cellular cargo?
2. Autophagosome formed
3. Fusion with lysosome
4. Autophagolysome formation and cellular cargo degradation
5. Products of degradation released back into cytoplasm
51
What is the function of the cytoskeleton
- gives cell shape and mechanical resistance to deformation
- actively contract - allows cell to migrate/move
- involved in cell signalling pathways
- involved in uptake of extracellular material (endocytosis)
- segregates chromosomes during cellular division
- involved in intracellular transport (move through cell)
- forms specialised structures such as flagella and cilia
52
What are the 3 types of filament within the cytoskeleton of a cell and what are their functions
Microfilaments (actin): determine shape of cell’s surface & control locomotion
Microtubules: determine positions of membrane enclosed organelles and direct intracellular transport
Intermediate filaments: provide mechanical strength - resist tension - cell to cell adherence
See “cells 3” lecture, slide 4 for diagrams
53
How are intermediate filaments involved in cell adherence
Transmit shearing forces through desmosomes between cells
54
Why can staining for intermediate filaments be useful
If a cell in an organ becomes cancerous and spreads - will carry intermediate filament - so you can identify where the cancer originated (different intermediate filament subtypes for different types of cells)
55
What do epithelial cells attach to basal lamina through
Hemidesmosomes
56
Describe the structure of microfilaments
Actin filaments are connected deep to the plasma membrane
57
Describe the role of microfilaments
Essential for cell movement and cell shape - associate with myosin to form contractile structures (contract and relax)
Role in phagocytosis - move to engulf
Shape the cell membrane forming lamellipodia and filopodia
Form core of microvilli
58
Describe the structure of microtubules
- Hollow tubes formed from molecules of alpha and beta subunits
- 13 subunits form protofilaments that are arranged as a helix - gives it polarity
59
What is the role of microtubules
- Form tracks that determine the location and movement of organelles and intracellular vesicles
- grow from an area (centrosome) and extend to the cell periphery
- form mitosis spindle used in cell division
- form the core of cilia and sperm cells
60
Describe the structure of centrioles
- important part of centrosomes (main place where microtubules are organised)
- arranged in pairs within the centrosome
- can be the basal body - the anchorage point of microtubules and other proteins
61
Describe the structure of cilia
- hair like cellular appendages with microtubules at the centre
- arranged as a ring of 9 special doublet microtubules with a single pair of microtubules at the centre (9+2 arrangement)
- anchored into a basal body
- 10-15 um long
For diagram see lecture “cells 3” slide 14
62
What is the function of cilia
In humans: move fluid over surface of cell in one direction
63
Where can cilia be found
Respiratory tract and female reproductive tract
64
Describe the structure of flagella
- hair like cellular appendages that have a bundle of microtubules at the centre
- longer than cilia (up to 200um long)
- 9 doublet microtubules and 2 single central microtubules
65
What is the function of flagella
Locomotion:
| Contain motor protein dynein- helps movement - whip like motion due to length
66
Where can flagella be found
Sperm cells
67
Describe the structure of microvilli
- finger-like protrusions on the apical surface of epithelium
- number and shape correlate to absorptive capacity
- formed from actin microfilaments typically 1-3um long
- actin anchors to the terminal web which stiffens the microvilli keeping the actin bunches at right angles to the cell
- terminal web is composed of intermediate filaments
68
8 functions of skin
```
Protection - barrier
Control of evaporation
Sensation - nerve endings
Absorption - eg nicotine patch
Manufacture vitamin D - from UV - needed for calcium absorption
Thermoregulation
Storage and synthesis - storage of lipids and water
Excretion - perspiration
```
69
Draw and label the strata of epidermis
Skin lecture
| Slide 7
70
What is the function of keratinocytes, melanocytes, Langerhans cells and merkel cells
Keratinocytes- produce keratin
Melanocytes - synthesise pigment melanin - located in basal layer
Langerhans cells - antigen presenting - form part of immune system - found in spinous layer
Merkel cells - sensitive mechanoreceptors - essential for light touch
71
What can a change in size or appearance of moles sometimes indicate
Dysplasia which can progress to malignant melanoma
72
Draw a labelled diagram of the layers of skin including the sub layers of the dermis
See skin lecture
73
What is the dermis composed of
Dense regular connective tissue - abundant in collagen
74
Give the name for the smooth muscle bundle associated with hair follicles
Arrector pili muscle
75
What are the three types of unencapsulated receptors in the skin
Merkel cells:
- light touch and sensing an objects texture
Free nerve endings:
- temperature, pain, itching
Root hair plexuses:
- detects movement of hairs
76
Name the four encapsulated receptors in skin
Meissen (tactile) corpuscles:
- light touch
Pacinian (lamellar) corpuscles:
- sensing coarse touch, pressure and vibrations
Krause end bulbs:
- genitalia - sense low frequency vibrations
Ruffin corpuscles:
- stretch or twisting
77
What are the structural elements of CT
Cells
Fibres
Ground substance
78
Name and describe the main cell in CT
Fibroblast
```
V active
Produces fibres and ground substance
Abundant and irregularly branched cytoplasm
Extensive RER
well developed golgi
When inactive - fibrocytes
```
79
What are the three types of fibres in CT
Collagen
Elastic
Reticular
80
Describe type I to IV of collagen
1. Tensile strength - 90 % of total collagen
2. In hyaline and elastic cartilage
3. Reticulum - wound healing - lymphoid organs
4. In basal lamina
81
How is a collagen fibre assembled
1. 3 @polypeptide chains combine - procollagen
2. Procollagen secreted from cell - proteolytic enzymes cleave loose ends - forms tropocollagen
3. align linear to form collagen fibril
4. Fibrils assemble to form collagen fibre
82
Describe glycosaminoglycans
Unbranched polysaccharide chains composed of repeating disaccharide units
Very large and attract water
Maintain tissue architecture - high viscosity
Provide passageway between cells - allows cell migration
83
Describe the three types of ordinary ct
Loose areolar:
- pliable and mesh like
- hold structures in place
Dense irregular:
- resistance and protection
- lots of collagen fibres - irregular arrangement
- found in dermis, submucosa of digestive tract, periosteum, fibrous capsules of organs
Dense regular:
- resistance in one direction/plane
- collagen aligned fo resist stress - run parallel
- tensile strength
- found in: ligaments, tendons and aponeuroses
84
Describe adipose tissue
Fat cells (adipocytes)
Lipid droplet surrounded by thin layer of cytoplasms and nucleus
Function:
- energy store, insulation, cushions
Found:
- under skin, kidneys, within abdomen, breasts
85
briefly describe collagen fibres
```
Tough
• Provides high tensile strength • Stretch
resistant
• Most abundant
protein – 25%
of total protein
mass
```
86
briefly describe elastic fibres
| where are they mainly found
```
• Long, thin
fibres
• Allow for stretch and
recoil
- Found in dermis, elastic arteries (aorta), lung, certain
cartilages
```
87
briefly describe reticular fibres
- Branched, thin
collagenous fibres
- form extensive delicate networks
- need specialised stains in order to see
- made up of type 3 collagen
- individual fibres - do not form bundles
88
what is the cause of scurvy
- lack of vitamin C
- Vitamin C is essential for collagen synthesis
- Imperfect collagen production causing abnormal bone growth, fragile capillaries leading to bleeding (gums) and loss of teeth etc
89
what is the cause of Ehler-Danos Syndrome
- Caused by a defect in the structure, production, or processing of collagen or proteins that interact with collagen
- Characterised by skin extensibility, joint hypermobility and tissue fragility
90
what is the cause of Marfan syndrome and symptoms
- defect in FBN1 gene which encodes fibrillar-1 i.e lack of fibrrillin in elastic fibres
- tall, thin individuals with long limbs, large hands, sunken chest
- defects of the heart valves and aorta - prone to aortic rupture
- typically have flexible joints and scoliosis
91
briefly describe ground substance and state its function
- highly hydrated gel, interstitial (tissue) fluid
- resists compressive forces on the matrix - provides mechanical strength
- functions as a molecular sieve through which nutrients, metabolites and hormones diffuse between blood capillaries and cells
- composed of glycosaminoglycans (GAGs), proteoglycans and adhesive glycoproteins
92
what are primary tissues and organs in relation to the lymphoreticular system. give two examples
- where lymphocytes are formed and/or mature
- Bone marrow
- thymus
93
what are secondary tissues and organs in relation to the lymphoreticular system. give two examples
- peripheral structures that maintain mature but naive lymphocytes and initiate immune response
eg:
- lymph nodes
- spleen
- Mucosa-associated lymphoid tissue (MALT)
- Gut-associated lymphoid tissue (GALT)
94
what is the function of B-lymphocytes
- Involved in humoral immunity
- Produce antibodies (proteins that recognise foreign substances (antigen) and attach themselves to it
- Mark invaders for destruction by other immune cells
95
what is the function of T-lymphocytes
- Involved in cell-mediated immunity (activation of phagocytes, antigen-specific cytotoxic T lymphocytes and the release of cytokines in response to an antigen; targets transformed and virus-infected cells for destruction by specific 'killer' cells
- do not produce antibodies
96
what are the four types of supporting cells of the lymphoreticular system
reticular cells
epithelioreticular cells
dendritic cells
macrophages
97
what is the function of reticular cells in supporting the lymphoreticular system
- Secrete type III collagen (reticular fibres) and ground substance
- Form intricate network in which the immune cells reside
98
what is the function of epithelioreticular cells in supporting the lymphoreticular system
- Specific to the thymus
| - Assist with T lymphocyte education
99
what is the function of dendritic cells in supporting the lymphoreticular system
- Antigen-presenting cells (APCs)
| - Monitor local environment for antigen which they process and present to lymphocytes
100
what is the function of macrophages in supporting the lymphoreticular system
Work both as APCs and phagocytes
101
describe the appearance of a lymphoid follicle
- Spherical accumulation of lymphocytes
- Pale staining germinal centre (activated B immunoblasts)
- Dark stained outer corona/mantle – represents a ring of small transient B lymphocytes
102
describe the appearance and function of the thymus
- Primary lymphoid organ responsible for programming
- CT capsule & septa divide organ into lobules
- Contains T lymphocytes (thymocytes) in a meshwork of epithelioreticular cells
- It has no lymphoid follicles
103
histologically how can you tell the difference between the cortex and medulla of the thymus
```
cortex = dark staining
medulla = light staining (less cells)
```
104
what is contained in the cortex of the thymus
- naive T lymphocytes that migrate to medulla
| - Macrophages responsible for phagocytosis of T lymphocytes that do not fulfil thymic education requirement
105
what is contained in the medulla of the thymus
- maturing t lymphocytes (assessment of immunocompetence)
- Hassall's corpuscles
- immunocompetent T lymphocytes pass Fromm medulla into blood circulation
106
what cell makes up Hassall's corpuscle of the medulla and what do they produce
Concentrically arranged, flattened epithelioreticular cells producing keratohyalin (similar to SSK epithelium)
107
what is the blood-thymus barrier composed of and what is its function
- Prevents circulating antigen reaching the T lymphocytes before their immunocompetence has been determined
Comprised of:
- Continuous endothelium of blood capillaries
- Thick basal lamina
- Epithelioreticular cells
- Macrophages
108
describe the histological appearance of lymph nodes and their function
- Deal with lymph-borne antigens - all tissue fluid-derived lymph is filtered by at least one node before returning to the circulation
- Outer curved boundary – afferent lymphatic vessels enter
- Hilum (H) – efferent lymphatics leave (also vascular & neural connections)
109
describe the outer cortex, inner cortex (paracortex) and medulla of a lymph node
Outer cortex:
- Subcapsular sinus & trabecular sinuses
- Meshwork of reticular fibres, dendritic cells & macrophages
- B lymphocytes organised into follicles
Inner cortex (paracortex):
- Few or no follicles
- mostly T lymphocytes
Medulla:
- medullary cords- branched extensions of lymphoid tissue from inner cortex
- separated by medullary sinuses
- dendritic cells and macrophages occur
110
what is the name of the connective tissue that surrounds the entire muscle
epimysium
111
what is the name of the connective tissue that surrounds each fascicle of a muscle
perimysium
112
what is the name of the connective tissue that surrounds each fibre of a muscle
endomysium
113
what gives muscle its striated appearance
Striations represent the repetitive contractile units, sarcomeres, consisting of segments of myofilaments
114
what is the name for the distance between 2 z-lines in a muscle fibre
Sarcomere
115
what are the light bands and dark bands in muscle fibres
```
I band (Light):
- Composed of actin myofilaments that are anchored to the z-line
```
A band (Dark):
- Represents the overlap between actin and myosin except at the H band
- Myosin anchored to m-line
116
what is the function of t tubules in muscle fibres
Function of t-tubules is to carry wave of depolarisation into fibre for contraction to occur
117
what is the function of blood
- Delivery of nutrients and oxygen directly or indirectly to cells
- Transport of wastes and carbon dioxide away from cells
- Delivery of hormones and other regulatory substances to and from cells and tissues
- Maintenance of homeostasis by:
acting as a buffer
participating in coagulation
assisting with thermoregulation
- Transport of humoral agents and cells of the immune system that protect the body from pathogenic agents, foreign proteins, and transformed cells e.g. cancer cells
118
what is the lifespan of a red blood cell
120 days
119
Why are erythrocytes biconcave?
↑ Surface area – more haemoglobin molecules closer to plasma membrane
Less distance for O2 and CO2 to diffuse
Extremely deformable
Less likely to rupture
120
what is the lifespan of a leukocyte
Life span of up to several years
121
what is the difference between granulocytes and agranulocytes
Granulocyte:
- Cytoplasm packed with granules
- Nucleus has 2 or more lobes (polymorphonuclear)
- Neutrophils, Eosinophils & Basophils
Agranulocyte:
- Cytoplasm with few or no granules
- Nucleus not lobed
- Mononuclear
- Lymphocytes & Monocytes
122
describe a neutrophil:
- percentage of all WBCs
- physical appearance
- when it responds
- life span
- 60-70%
- Nucleus has 2-5 lobes
- Numerous cytoplasmic granules
- Respond most quickly to tissue destruction by bacteria or fungus
- Numbers increase during acute bacterial infections such as meningitis and appendicitis
- Short life span (1-2 days)
123
describe a eosinophil:
- percentage of all WBCs
- physical appearance
- when it responds
- 2-4% of circulating WBCs
- Bilobed nucleus
- Large refractile granules (lysosomes)
- Regulate local inflammatory responses due to allergic or parasitic action
124
describe a basophil:
- percentage of all WBCs
- physical appearance
- when it responds
Less than 1% of circulating WBCs
Irregularly-lobed nucleus
Numerous large overlying granules which often obsucre the nucleus
Granules contain heparin (anti-coagulant) and histamine (vasodilator)
Associated with systemic inflammation and allergies
125
describe a lymphocyte:
- percentage of all WBCs
- physical appearance
- when it responds
- 20-25% of circulating WBCs
- Nucleus is spherical and densely stained; no granules
- Usually present in tissues
Involved in adaptive immune responses:
- B-lymphocytes → plasma cells (produce antibodies)
- T-lymphocytes (cell-mediated response)
126
describe a monocyte:
- percentage of all WBCs
- physical appearance
- when it responds
- 3 – 8 % of circulating WBCs
- Kidney/U-shaped nucleus
- Large cell (12- 20μm)
- Transform into a macrophage in tissues and organs (e.g. osteoclasts, Kupffer cells, alveolar macrophages)
127
what is the order of abundance for white blood cells
```
Neutrophil
Lymphocyte
Monocyte
Eosinophil
Basophil
```
Never let monkeys eat bananas
128
describe haemostasis
When endothelial injury occurs, the endothelial cells stop secretion of coagulation and aggregation inhibitors and instead secrete von Willebrand factor which initiates the maintenance of haemostasis after injury
Platelets and fibrin (in blood plasma) bind together with cells to form platelet plug
Three major steps involved:
1. Vasoconstriction of blood vessel wall
2. Temporary blockage of a break by a platelet plug - platelets attach to exposed collagen of vessel wall and release the contents of their granules, leading to aggregation of other platelets to the area
3. Blood coagulation, or formation of a fibrin clot – a fibrin mesh (from blood plasma) binds together with cells and platelets
129
List and describe the layers of the wall of the heart.
Epicardium:
- Visceral pericardium - simple squamous epithelium
- Subepicardium - loose connective tissue and adipose tissue containing coronary vessels and nerves that supply the heart
Myocardium:
- Thickest layer
- Bundles and layers of cardiac muscle cells
Endocardium:
- Smooth inner lining of endothelial cells
- Subendocardium - loose connective tissue containing small blood vessels and branches of the conducting system of the heart
130
Describe the impulse conducting system of the heart.
Sinoatrial (SA) Node – Pacemaker:
- Located in wall of superior vena cava & right atrium, deep to epicardium
- Specialised cardiac muscle fibres (lots of CT between fibres)
- Possesses its own blood supply
- Causes atrial contraction
Atrioventricular (AV) Node:
- Located in septum between atria
- Begins ventricular contraction
Atrioventricular Bundle – Bundle of His:
- Bundle of fibres that enter interventricular septum
- Divides into 2 branches of Purkinje fibres
Purkinje fibres:
- Occur in dense CT of endocardium
- Specialised cardiac muscle fibres – larger (x2 approx.)
- Supply papillary muscles first, then apex of heart
- Causes wave of ventricular contraction
131
Compare and contrast the structure of arteries and veins.
Arteries:
- Carry oxygenated blood (except pulmonary artery)
- Takes blood away from the heart
- Wall thick in comparison to lumen diameter
- No valves
- Two main types;
> Elastic arteries(conducting vessels)
> Muscular arteries (distributing vessels)
Also, arterioles
Veins:
- Carry deoxygenated blood (except for pulmonary veins)
- Takes blood to the heart
- Walls are thin in comparison to lumen diameter
- Tunica media relatively thin compared to arteries
- Tunica adventitia relatively larger compared to arteries
- Possess valves
132
describe the layers of a vessel wall
see heart and blood vessels lecture - slide 15 for diagram
```
Tunica Intima (Interna):
- Endothelium & CT (subendothelium)
```
Tunica Media:
- Smooth muscle, collagen and elastic fibres (relative amounts)
Tunica Adventitia (Externa):
- Loose connective tissue (relative amounts)
- Can have blood vessels and nerves
133
describe the three types of capillaries
Continuous capillaries: are continuous in the sense that the endothelial red blood cells provide an uninterrupted lining, and they only allow smaller molecules, such as water and ions to pass through their intercellular clefts
Fenstrated: These are found in some tissues where there is extensive molecular exchange with the blood such as the small intestine, endocrine glands and the kidney. The 'fenestrations' are pores that will allow larger molecules though. These capillaries are more permeable than continuous capillaries.
Discontinuous capillaries: have open spaces between endothelial cells are very permeable and sometime permit the passage of blood cells between them. These are found in the liver, spleen and bone marrow.
134
name 6 functions of the respiratory system
- Moves air to and from exchange surfaces
- Exchange of CO2 and O2 between atmosphere and blood
- Protects:
>airways from environment e.g. dehydration, temperature changes, foreign bodies;
> airways & other tissues from pathogens;
- Sensation of smell
- Sound production
- Assists in regulation of blood volume, blood pressure, & control of body fluid pH
135
describe the function of nasal conchae
- Increase surface area of nasal cavity
- Lined with PSCC epithelium
- Contain venous sinuses and tubuloacinar seromucous glands
- Cause air turbulence to trap foreign matter
- Blood acts as a heat exchanger, warming the incoming air
- Filters air- pollutants are trapped in the mucus
136
function of the trachea
Conducts air into thorax
Withstands stretch
Transports mucous blanket – mucociliary escalator
137
what is the function of the larynx
Connects pharynx to trachea
Responsible for phonation (phonetics - speech sounds)
Epiglottis guards against entry of foreign bodies
138
describe - physical features and function - of the pleura of he lungs
- Two layers of opposing mesothelium
>Visceral pleura
>Parietal pleura
- Composed of a fibroelastic CT
- Pleural cavity in-between containing serous fluid
- Protection from friction against chest wall during breathing
139
Name the types of epithelium found in different parts of the alimentary tract.
Stratified Squamous Non-keratinising:
- oral cavity
- oesophagus
Simple Columnar:
- stomach
- small intestine - duodenum, jejunum, ileum
- large intestine/colon
* Simple columnar→ SSNK → SSK:
- rectum
- anus
140
Describe the epithelial specialisations of the oral cavity and oesophagus.
Hard palate:
- Anterior 2/3
- Lined with SSK epithelium
- Underlying bone
Tongue:
- Dorsum – specialised epithelium (taste buds and papillae)
- Ventrum – SSNK epithelium
Gums (Gingiva):
- SSK epithelium
Soft palate:
- Movable posterior 1/3 of palate
- Lined with SSNK epithelium but no bony skeleton
Cheeks:
- SSNK epithelium
141
Describe the epithelial specializations of the small and large intestines and their principal epithelial cells.
Small intestine:
- Large surface area required to maximise absorption - entire small intestine has SA of 250m2
- Three features facilitate this:
1. Pilcae Circulares:
> circular ridges projecting into the gut lumen
2. Villi:
> finger-like structures projecting from plicate circulares
> crypts of Lieberkühn at base of villi
3. Microvilli:
> microscopic finger-like structures projecting from apical surface of absorptive enterocytes
Large Intestine:
- Simple tubular glands containing numerous goblet cells (mucus production), colonocytes (absorptive) and enteroendocrine cells
142
Describe the relationship between the exocrine and endocrine components of pancreas and the structural features of each
Organ divided into lobules by CT septa (lobulated)
Exocrine:
- Serous acini and branched ducts
- Produce enzymes for digestion of food, including trypsinogen, lipase and amylase.
- Produced in an inactive form to avoid self-digestion
Endocrine:
- Islets of Langerhans & blood capillaries
- Islet cells produce hormones including insulin, glucagon, somatostatin and pancreatic polypeptide
143
list some of the functions of saliva
- Digestive, lubricating and protective functions
- Limits bacterial activity
- Epidermal growth factor released to aid wound healing
- Gustin released to help detect taste
- maintains integrity of tooth enamel
144
list some of the functions of the liver
- Exocrine gland function – production of bile
- Endocrine gland function – production of plasma proteins
- Nutrients absorbed in digestive tract processed and stored in liver for use by other parts of the body e.g. carbohydrates stored as glycogen
- Degrades toxins, drugs, alcohol etc.
- Destruction of worn out red blood cells
145
what is the function of Juxtaglomerular Apparatusin the kidneys
Function: to monitor and adjust blood pressure
146
what type of epithelium lines the PCT
simple cuboidal
147
describe the epithelium lining of the loop of Henle
Thin portion lined by simple squamous epithelium
| Thick portion lined by simple cuboidal epithelium
148
describe the epithelium lining of the collecting ducts in the kidney
Lined by simple cuboidal/columnar epithelium
149
describe the development of endocrine glands
see endocrine lecture slide 4 for diagram
Multicellular glands begin as down-growing buds of cells as in B3 & B4
Endocrine glands develop by the isolation of the bud of cells from the surface epithelium (C4)
This isolated mass then acquires its own blood supply (D4)
