Summary of cell biology Flashcards
(190 cards)
1
Q
Steps in intiation of protein synthesis?
A
Traslation begins at AUG which small ribosomal subunit searches for as TRNA binds.
Eukaryotic initiation facor (EIF-2) binds.
if correct pairing EIF-2 ATP is hydrolysed to ADP (providing headgrowth) and dissociates. Large subunit then associated.
If incorrect ATP not hydrolysed, EIF-2 not dissociated, so tRNA falls off.
2
Q
Steps in translation of protein synthesis?
A
Incoming tRNA is associated with elongation Factor EF-TU-GTP.
If correct base pairing, promotes GTPase activity, GTP hydolysed to GDP and EF-TU dissociates and the tRNA is captured.
If incorrect tRNA no GTP-ase activity tRNA falls off.
Another Elongation Factor binds, this time close to the A site. As the GTP is hydrolysed to GDP causing a conformational change of EF-G, prmoting the movement of the tRNA into hybrid state e.g from A to P or P to E site.
3
Q
Steps in termination of protein synthesis?
A
No tRNA for the stop codons, so releasing factor binds to A site. Hydrolysis reaction released water.
Peptidyl transferase binds H2O to the C terminus, cuasing the dissociation of the protein.
The releasing factor causes the dissociation of the ribosome.
4
Q
Target sequence is cut off by?
A
Signal peptidase
5
Q
What are two heat shock chaperones?
A
HSP70- allows refolding under heat stress.
HSP60- hides hydrophobic regions.
6
Q
SIgnal for nuclear import? uses..
A
Nuclear localisation signal, ATP
7
Q
Sequence of mitochondrial import?
A
Protein has location signal which is recognised by a receptor on the outer membrane. Bond and form a TOM complex.
This complex then looks for the TIm23 complex on inner membrane.
The two are brought closer together, protein moves through and signal peptide cleaved off.
8
Q
Proteins desined for …(5) must be inserted into the ER membrane to reach their destination.
A
ER, Golgi, lysosome, secretory, plasma membrane.
9
Q
Signal sequence for ER import is helped by?
A
Signal recognition particle (SRP).
10
Q
Steps for ER import?
A
The signal sequence of the protein binds to a SRP which binds to its SRp receptor on the ER membrane.
This then finds the protein translocator and the SRP is recycled.
11
Q
4 functions of the Endoplasmic Reticulum?
A
Protein synthesis.
Storage e.g. glycogen
Tranport
Detoxification e.g. cytochrome C.
12
Q
4 more specific functions of the SER?
A
Synthesis of Cholesterol and phospholipids
Synthesisand storage of glycogen and glycerides
Storage of Calcium
Steroid hormone production
13
Q
Two examples of Calcium release in cells?
A
Acinar cells-Ca release
Sarcoplasmic reticulum at neuromuscualr junction.
14
Q
3 functions of the golgi apparatus?
A
Packaging and modify secretions for exocytosis
Renewal and modification of the PM
Delivery of materials to other organelles.
15
Q
Movemnt away from the ER…
Towards…
A
Anterograde
Retrograde
16
Q
Three coats and their functions?
A
Clathrin= formation of vesicles at the cell surface e.g. clathrin pits.
COP I= movement through Golgi
COP II= Promotion of vesicles from the ER to Golgi.
17
Q
How do vesicles reach their correct targets?
A
V SNARES are encorporated into the vesicle, so even when they lsoe their coat these remain.
V SNARE interracts with T SNARE on the target cell as they are complimentary.
Form a tight junction and allows fusion with PM and import.
V SNARES recycled.
18
Q
Vesicular transport model vs Cisternal maturation model?
A
VT: Golgi is a static structure proteins progress from one cisternae to the next by vesicle transport
CM: Golgi is dynamic, cisternae progress through the apparatus from cis to trans.
19
Q
3 pathways membrane proteins delivered to cell surface?
A
- Signal mediated diversion to lysosomes
- signal mediated diversion to secretory vesicles ( e.g. regulated by hormones binding)
- Constitutive pathway (unregulated)
20
Q
5 fates of endocytosed material?
A
- Degredation- by lysosomes.
- Transport back to cell surface
- Transport through
- Storage
- Recycling
21
Q
Phagocytosis > ….> Pinocytosis
A
0.5um
22
Q
What is Frustated Phagocytosis?
A
When two macrophages both extend psudopods round a bacterium but cant stretch round fully as other in the way
23
Q
How is cholesterol synthesised in
A
LDL bind to LDL receptors on membrane, whihc is positioned in a clatherin pit.
Vesicle with LDL and receptor bound uncoated
Fused with early endosome.
A transport vesicle buds off to recyle the LDL receptor to the cell surface, while the now lysosome breaks down the LDL by hydrolytic enzymes to synthesise the cholesterol.
24
Q
WHat is Macropinocyrosis?
A
When cells ruffle and non-selectively endocytose material.
25
Clathrin structure?
Made of a light and heavy chain, hass three legs.
26
4 compenents of the cytoskeleton?
Microtubules (e.g. attatch to centrosome) Microfilaments (e.g. actin)
Intermediate filaments
Associated proteins
27
Structure of microtubules?
Made of alpha and Beta tubulin dimers, with a GTP associated with each dimer. B exposed at growing plus end and alpha embedded in a helix.
50 KD
28
What does phosphorylation do to microtubules?
Phosphorylated: dynamic e.g. in mitosis
De: static.
29
Why does polymiserisation of microtubules happen on to the plus side? In what form?
Dimers in the GTP form can be added. Considering hydrolysis follows the polymerisation from the - to the + end, the dimers at the - end are already in the GDP state, whereas the GTP cap at the + side (which has not get got hydrolysed) can be added to or shrunk.
30
Function of microtubules? (3)
1. Cell shape
2. Movement of organelles
3. Cell division
31
What are MAP's?
Microtubule associated proteins:
- Motor proteins: Dynein and Kinesin
- Promote assembly: MAP2 and TAU
32
Structure of microfilaments?
Fires of homomeric actin, with bound ATP (minus end ADP form often when filamentous)
Can be G globular of F filamentous Actin.
42KD
33
What are the cell specific Actin Microfilaments?
Striated: Alpha sk or Apha c (skeletal and cardiac)
Smooth: Alpha sm and Gamma sm
Non muscle: Beta or Gamma
34
Example of Rapid actin polymerisation?
Acrosomal reaction in sperm force into egg.
35
4 types of Actin binding proteins?
- Gelsolin (caps/severs/nucleates)
- Profilin (monomer binding)
- Fimbrin (bind actin filaments together)
- Thymosin (Monomer binding also)
36
Structure of Intermediate filaments?
Rope like coiled coiled structures
37
5 intermediate filament subunit types?
Class I and II in epithelial keratins
Class III in muscle e.g. Desmin
Class IV make neurofilaments
Class V- nuclear lamins
38
Two microtubule motors and difference?
Dynein: Minus end directed (grows from) found in cilia or cytoplasm
Kinesin: Plus end directed and only in cytoplasm.
39
Two microtubule motors differences in binding to organelles?
Kinesin: Binds directly to organelles
Dynein: Binds indirectly
40
Roles of three main cytoskeletal components in mitosis?
Microtubules: Movement of chromosomesActin Microfilaments: Cytokinesis
Intermediate filaments: Nuclear membrane breakdown
41
How is the nuclear envelope broken down in mitosis?
Lamins (type of IF) holds the nuclear envelope together.
In prophase these Lamins get phosphorylated so break apart.
Dephosphylate in late telophase to reform.
42
What are the three microtubules that come out of the spindle poles in cell division?
Atral MT from the centrosomes
Kinetochore MT connect to kinetochore of chromosomes.
overlap microtubules maintain rigidity.
43
How do the daughter chromosomes move towards the poles?
Shortening of the kenetrochore Microtubules closer to the centrosome by depolymerisation
lengthening of the overlap Microtubules so centrosomes get further apart
44
How does cytokinesis happen?
Contractile ring made of Actin myosin constricts until is pinched off.
45
What is the structure of cilia and flagella?
The Axoneme:
9-2 microtubule assembly, 9 pairs of outer doublets (one complete A fibre, one incomplete B)
and one inner pair (of 2).
Has Dynein arms that contact with adjacent doublets
and inner ones.
Has radial spokes and Nexin also.
46
Difference between cilia and flagella?
Length:
cilia= 2-10um length 0.5 width &Whip action
Flagella= 100-200um length and 0.5 width &wave action
47
What are Basal bodies? structure?
Protein structures found at the base of cilia or flagella formed by centioles. They have a 9x3 microtubule structure.
48
How does Dynein cause shape change?
when dynein hydrolyses ATP it generates force that causes microtubules to slide over each other or bending.
49
Describe the sarcolemma in terms of its banding?
Actin (thin filaments) only outer section connected to the Z line is called the I band.
Region where only the thick myosin is present is the H band and both is called the A band. (dark band)
The central line is the M line, .
50
Calcium binds to ..... which is also bound to and moves .... out the way. This exposes the ...... binding sites. The head flexes. ........ binds to ........ in order to break the cross bridge and bind further up causing the power stroke.
```
Troponin
Tropomyosin
Myosin
ATP
Myosin
```
51
Structure of the Myosin filament?
Coiled coil of two alpha helices with a hinge region and two head regions just after two light chains bind.
52
Describe Amoeboid movement?
Gel like structure with actin meshwork around the edge which can polymerise and and the gel follows.
53
Describe how Filapodia move?
It has focal adhesions that contain inegrins that bind to the surface of the ECM.
Actin polimerisation of plus end protudes the lamellipodia.
The end of the structure contracts and the old adhesions break and new form further along.
54
What are tight junctions?
(occluding junction)
Completely impermeable junction between epithelial cells. Can vary permeability for paracellular transport (in gap between cells not between).
55
Structure of tight junctions?
```
Transmembrane across the PM's sealing them.
Claudin and Occludin do this.
ZO proteins (zonula Occlude) link to claudin and the cytoplasmic actin filaments providing support.
```
56
What is the purpose of tight junctions?
Preserves the cells variation/polarity, segregating lipids and proteins on the PM
e.g. on the basolateral PM (outer facing) having phosphotidyl whereas on the apical glycolipid and cholesterol.
57
What are gap junctions?
Allows communication between cells made of clusters of transmembrane proteins forming a 2-4nm gap.
Forms pores of 2 x connexon which is made of 6 subunits of Connexin.
(Innexins in invertebrates)
58
What do Gap junctions let through? Regulated?
Allows passage of ions, AA, ATP, CAMP, IP3
| Regulated as PH and Ca can open or close depending on levels- prevent overload.
59
What is he structure of an adherin junction?
Catenins bind to the actin of the first cell, and also to the cadherin dimers which span across the intracellular gap.
60
What is the function of an adherin junction?
Ca dependent, homophilic interactions of adhesion belts. These allow for invagination of epithelial cells where a section can be pinched off making this contractile in length.
61
What is Pemphigus?
Autoimmune skin blistering, removes desmoglein of the cadherin family, reduces the inegrity of skin
62
What are desmosomes?
Member of the cadherin family but these link to Intermediate filaments instead in cell to cell connections.
63
What are hemidesmosomes?
Attatches cells to the Basal lamina via integrins or intermediate filaments.
64
Non junctional adhesion mechanisms?
Integrins, Ig like domains, Non Ca/mg dependent
65
Extracellular matrix function? (5)
- Maintain tissue integrity/shape
- Proliferation- anchorage dependent growth (a surface needed for mitosis
- Differentiation- affects cell differentiation
- Migration- provides ways to move
- Microbe defence
66
3 components of the extracellular matrix and two exaamples for each?
- Fibrous proteins: give structure e.g collagen, elastin
- Adhesion proteins: allow cell adhesion interract with cells e.g. Fibronectin, Laminin
- Hydrated macromolecules e.g. GAG's and Proteoglycans (protein + GAGs)
67
Structure of collagen?
Fibrocollagen 1 main ECM componenet.
Triple helix of 3 alpha chains
20-40 varients.
68
Disease associated with defects in collagen?
Ehlers- Danlos syndrome- very flexible skin but serious problems as arterials can rupture.
69
Collagen is extenisvely modified in the golgi how?
Hydroxylation of proline and lysine's
| Adding polysaccaride chains e.g. glycosylation of selected sugars.
70
....... cells make the collagen early form .... This is modified in the golgi. Self assmbly of ....chains makes the helix of ..... This is secreted out of the golgi before the ........ are cleaved into the final .... These are then bundled to make a collagen.....
Fibroblast, Pro alpha chain, 3, Procollagen, propeptides, fibril, fiber.
71
Elastin binds to ......... or ....... to form elastin .....?
Microfibers or fibrillin to form elastin fibres
72
Cross links between monomers of ...... form the final elastin structure by .....
Tropoelastin by Lysyloxidase
73
Mutation in Elastin causes what disease? In what gene?
Marfan's syndrome, mutation in FB1 gene (fibrilin 1 gene)
74
What are GAGs?
In the ECM. Charged polysaccarides that bind to proteins by covalent bonds to form protoglycans. They are all sulphated except hylauronic acid. Disaccarides 20-70 units long.
75
Features/ function of Hyluronic acid?
Less charged than other GAGS due to not being sulphated, which isn't normally linked to a protein. Used for space filling, resisting compression in joints due to water attracting to it. Is secreted across the PM
76
What are Proteoglycans? Structure?
In the ECM. GAG's + Protein.
| The backbone is often hyaluronon with linker proteins binding to the proteoglycans . Long flexible hydrated gel.
77
Roles of Proteoglycans?
- Cushioning near tendons etc-highly negative so attracts cations eg Na so water follows
- Space filling- e.g. in embryogenesis
- Filtering- hydrated gel filters out small molecules e.g. in kidneys stops transfer between blood and tubules
- Signal binding
78
Proteoglycans can be used as a cure for?
Athritus for a few days but short lived.
79
What is fibronectin?
An adhesion glycoprotein in the ECM.
It has binding sites for: Heparin, collagen, cells, GAG's, fibrin and fibronectin itself.
RGD sequence needed for binding.
80
Function of fibronectin?
Binds to ECM, useful for wound heeling and embryonic development.
81
What is the structure of Laminin? Function?
3 strand heterotroma of alpha, Beta and Gamma binded by disulphide bonds. e.g. in Basal lamina and promotes development of axons.
82
What are integrins?
They bind the ECM to the plasma membrane as they span the PM. They bind to Fibronectin and other ECM proteins via a RGD sequence. It links to the Actin filaments in the cytoskeleton of the cell.
83
What is the structure of integrins? (lecture 21 diagram)
Two major subunits one alpha, one Beta. The Beta goes right throught the PM to bind to actin, whereas the alpha is in two, with a transmembrane section binded to the ECM section by a disulphide bond.
84
Associated disease with integrins?
Glanzmanns thrombosthenia- platelets dont bind to each other therfore bleeding time increases.
85
Intergrin binds to the actin through .....
focal adhesions.
86
What are the four basic tissues?
Nervous, Connective tissue, Muscle and epithelial
87
What germ layer is each of the four basic tissue types?
Muscle- mesoderm
Connective tissue- mesoderm
Nervous- ectoderm
epithelial- all three
88
Three types of muscle?
Skeletal (voluntary)
Cardiac (heart)
Smooth (involutary)
89
Features of skeletal muscle? (4)
Multinucleate, striated longitudinally, voluntary, in long unbranched fibers
90
Features of cardiac muscle? (5)
Uninucleate, striated, highly branched with incalated discs, has an inherent rhythm
91
Features of smooth muscle? (5)
uninucleate, unstriated, unbranched, spindle shaped, involuntary
92
Many myofibrils make a muscle fiber. ...... surrounds a skeletal muscle fiber to make a bundle called a ........, in which the ..... surrounds. These make the final tendon which the ...... surrounds.
Endomysium, fasicle, perimysium, epimysium
93
What are myofibrils?
Chains of sarcomeres
94
The stem cells for muscles are..... These differentiate into ......... then into the muscle fibers. This process is called.....
Satellite cells, myocytes, myogenesis
95
WHat are the two myofilaments? Lengths widths?
Think: myosin (1.6 um long, 15nm diamter)
Thin: Actin (10 um long, 8nm diameter)
96
Structure of the actin in the sarcomere?
F actin made of two alpha chains. This is wrapped in the coiled actin protein tropomyosin and tropinin complex.
97
Charactoristics of epithelia? e.g. location (5)
- Rests on basement layer
- Avascular
- Not innervated
- Cell junctions particularly common on basal layer e.g. desmosomes, tight junctions, focal adhesions
- Always at borded to protect from pathogens
98
Function of epithelia (3)
Protection e.g. skin
Absorption e.g. gut lining
Secretion e.g. glands, goblet cells
99
Two main types? Two exceptions?
Simple- Only one layer all touching the BM
Stratified- Form layers not all resting on the BM
Exception:
Pseudo stratified- looks stratified but all resting on BM
Transitional epithelium- Changes structure when relaxed vs stretched
100
Differences between simple squamous epithelia, cubiodal and columnar?
- Squarmous: Very thin flattened cells with oval nuclei, permeable e.g. alveoli, capillaries, glomeruli
- Cubiodal: roughly square cells with round nucleus, secretion and absorption e.g. kidney tubules, ducts of glands
- Columnar: Taller than wide with oval nucleus, where lots of activity can have microvilli e.g. small intestine, bronchus with goblet cells and cilia, more active cells in the gut.
101
Cilia attatches to the cell by...
Basal bodies
102
Function of stratified epithelia?
Protective function where continuously being worn down e.g. heels of feet.
103
Three subtypes of stratified epithelia?
Kertainised e.g. skin,
Unkeritinised e.g. mouth, osophagus
Cuboidal- rare only in a few large ducts
104
Features of pseudo stratified that makes it suitable for the role?
stretchable e.g. urinary bladder stretches as fills, or trachea
105
Basement membrane made of? And stains positive for......
Collagen IV and fibronectin
| Per-iodic Acid Schiffs (PAS) stain
106
Protein is secreted by ..... glands. These are dark in colour due to lots of ..... and have .... nuclei.
Whereas mucus is secreted by ..... glands. These are light due to more ..... and have ... nuclei.
Serous, RER, flat
| Mucous, SER, round
107
Two types of connective tissue and examples?
Proper e.g. genral tissue connecting between organs etc.
| Specialised e.g. bone, blood
108
Three functions of connective tissue proper? (2)
- Packs around and holds organs in place
| - Involved in storage e.g. fats
109
3 Components of Connective tissue?
Cells, fibres, matrix
110
Two types of fibres in connective tissue?
collagen and Elastic fibres
111
Features of collagen in the connective tissue? (4)
White, thick, unbranched, for strength and support (type 1 in bones and tendons- inextensible)
112
Features of elastic fibres in the connective tissue?
For stretch and recoil e.g. in cartilidge, yellow, thin, highly branched
113
Difference in the pattern of collagen in the skin vs tendons? why?
In tendons its packed very regularly whereas in the skin it's irregularly packed so that it can line up and stretch.
114
Collagen is made by .......... 3 ...... bind to make ...... 3 of these alpha helices then make the final collagen.
Fibroblasts, Pro-collagen, Tropocollagen
115
Typically ..... genes are needed to make collagen. Roughly 1/3 of the AA's are ..... or ....... Vitamin ... is needed for production.
34, glycine and proline, vitamin C
116
What are the three types of collagen?
Type 1, 4 and 7.
117
Which is the most common collagen? Uses? why?
Type 1, used in bone, tendons and skin as it is large and unbranched.
118
Use of type 4 collagen? why?
Used as the basement membrane as it is arranged in sheets and used to filter.
119
Use of type 7 collagen?
Anchors larger strands e,g type 4 to glycoproteins or fibrils to the BM of skin.
120
Elastic fibres are made by ....... and contain the hydrophobic protein ...... which ....... often surrounds
Fibroblasts, Elastin, Fibrillin
121
Types of cells found in connective tissue?
Mast cells, fibroblasts, fibrocytes, osteocytes, adipocytes, plasma cells, macrophages, chondrocytes
122
Fibroblasts vs fibrocytes?
- Fibroblasts- active with euchromatin, lots of RER, produce fibers, abundant cytoplasm
- Fibrocyte- inactive with heterochromatin, little RER, scant cytoplasm.
123
Two adipose cells?
White- Unilocular (only one fat droplet with triglyceride stored)
Brown-Multilocular (smaller numerous fat droplets) lots of mitochondria giving brown colour and produces heat (good for hibenating)
124
White fat starts out as .... shaped and matures into fat cells
spindle
125
Surrounding the fat vesicle is.....they have receptors for ....(2) to be converted back for energy.
collagen type III.
| Insulin, gluco-coricoids etc
126
Matrix in connective tissue proper is produced by ..... and is mostly made up of ....
Fibroblasts
| GAGs
127
What are GAGs?
Large unbranched, polysacaccharide chains, very hydrophillic and negative (retains cations therefore water diffuses in keeps turgid). Can form protoglycans.
128
WHat stain shows elastic fibres?
Weigerts
129
Three ways neurones are different other cells?
- Metabolism specialised
- Contain selective ion channels to produce action potentials
- Long axons and cell processes radiating from cell body
130
Neurones are surrounded by supporting ....
Glial cells.
131
In the periphery nervous system the glial cells which myleinate are .... whereas in the central it is ...... Which surrounds only one neurone and which many?
PNS: Schwann cell which surrounds only one neurone.
CNS: Oligodendrocytes which surround many/parts.
132
Example of an inhibitory synapse?
Chloride ions are released which makes the membrane more negative therefore harder to reach threshold potential.
133
Synapse gap length?
400nm
134
When is acetyl choline used?
neurotransmitter used at a neuromuscular junction, in the autonomic nervous system from Pre to post and in the parasympathetic used between the post and target.
135
When are Glycine and glutamate used at a synapse?
Common excitatory in the CNS
136
When is GABA used at a synapse?
Common inhibitory in the CNS
137
When is noradrenaline used at a synapse?
Used in the sympathetic nervous system
138
Autoimmune disease that attacks the acetyl choline receptors at a neuromuscular junction? Symptoms?
Myasthenia gravis
| -muscle weakness, problems swallowing and eye movements
139
What are SSRI?
Specific serotonin reuptake inhibitors, these stop the reuptake of serotonin so act at the receptors longer, used to help depression.
140
3 main functions of Glial cells?
- Nutrition of neurons
- Myelination of neurons
- removal of debris and injured neurones
141
Astocytes strucure?
-starshaped nutritional cells that contact with both blood vessels and neurons carrying nutrients betwen.
142
What are microglia?
Phagocytic cells found only in the CNS engulf harmful material.
143
groups of cell bodies in the CNS vs PNS?
CNS: nuclei
PNS: ganglia
144
In the CNS axons are bundled together to form ....
tracts or pathways.
145
In the PNS the axons are surrounded by..... These are bundled together into a fasicle to be surrounded by ..... and the nerve is surrounded by .....
Endoneurium
Perineurium
Epineurium
146
Example of specialised connective tissue?
Blood
147
Erthrocytes make up .... cells per mm cubed.
| Whereas leukocytes is ....
5 million
| 4,000-11,000
148
In blood ...% is platelets and blood cells, ...% is plasma
45%, 55%
149
Formation of erythrocytes?
Anucleate, haemoglobin filled cytoplasm. Biconcave disc 7x2 micrometers.
5% haem, 95% globin (alpha and Beta chains)
150
What breaks down damaged erythrocytes?
the spleen
151
RBC's are produced by the process called..
Erythropoesis
152
....are the stem cells located in the bone marrow and give rise to RBCS.
Haemocytoblasts
153
Stem cells differentiate into ........ before RBCS. Why got this name? How turn into RBCs?
Reticulocytes
| Still has lots of RER and the ribosomes stain as lines called reticules. 2-3 days later RER disappears
154
Erythrocyte production is controlled by which hormone?
Erythropoetin
155
ratio of RBCs to WBCs?
1 WBC to 700 RBC
156
Increased WBC's is called ..... usually during an infection. Whereas decreased is .....
Leukocytosis
| Leukopenia
157
WBC production process is called...
Leukopoesis
158
Two main leukocyte types: examples?
Granulocytes: neutrophils, eosinophils, basophils
Agranulocytes: lymphocytes, monocytes
159
Two curcuits of the blood vessels? pressure in?
Pulmonary (to the heart)- low pressure
| Systemic (to body)- high pressure
160
Pulsatile flow is smoothened out by .... arteries particularly in the ... And blood pressure is maintained by the .... arteries
elastic
aorta
muscular
161
What are the three tunics?
Tunica intima: inner most, thin, smooth simple squarmous
Tunica media:middle thick in arteries less in veins
Tunica adventitia: outer, connective tissue elasic layer may include vasa vasorium
162
Which have a larger lumen veins or arteries? why?
Veins, less pressure
163
Elastic artieres example? Pressure?
Aorta, 120-160mm Hb
164
What is a probem of the huge pressure in elastic artieres?
Pressure on the intima, can cause damage, so no longer smooth flow so doesnt even out systolic pressure.
165
Muscular muscles have mainly ..
Smooth muscle
166
Whats an anteriogram?
radioactive substances inserted into blood vessels can see bloackages where gathers etc
167
WHat does microvasculature refer to?
The smallest network of vessels in circulation- capillaries, 5-10nm in diameter.
168
Structure of the capillaries?
Endothelium on the basement membrane, with occasional pericytes (contractile cells)
169
What is atheroma?
plaques of fatty deposits and calcuim build up on the intima cuasing turbulant flow resulting in a narrowed artery.
170
What is a thrombus?
A blot clot within the arteries, may stick to exposed collagen in damaged artieres and block
171
What is an aneurysm?
If atheroma extends into media smooth muscle its replaced by non-contactile tisue- bulges can burst.
172
What is Haemostasis?
The bodies reponse to blood vessel injury resulting in cell to cell communication between platelets and blood clotting proteins to stop the bleeding.
173
Normal blood volume is .....L if more than 30% is lost this can lead to .......
4-6L
| Hypervolaemic shock
174
4 Phases of blood clotting in Haemostasis?
Vascular phase, Platelet phase, coagulation phase, tissue repair and clot breakdown
175
What happens in the vascular phase? (4+4 detail for 4th)
-Vasoconstriction.
-Endothelial cells contract- expose basal lamina underneath to blood.
-Increases edothelial adhesion stick together-faciliating the attatchement of platelets.
-Endothelial cells release factors:
- ADP for platelet aggregation
- Tissue factor- for clotting
- Prostacylin- reduces spread of platelet
aggregation
- Endothelins
176
What do endothelins do? (3)
- Hormone which stimulates contraction (vasoconstriction) of smooth muscle in blood vessels- raise blood pressure
- promote mitosis of cells.
177
Platelets are formed from....
| by.....
Megakaryocytes in the bone marrow.
(polyploid- have more than two paired sets of chromosomes)
pockets of the cytoplasm surrounded by membrane budding off.
178
Function of platelets?
To stop bleeding by making the blood clot. At the site of epithelial damage- PLUG THE HOLE.
179
3 stages of platlet phase?
Adhesion, Activation, Aggregation (15 sec after injury)
180
Explain platelet adhesion in the platelet phase?
Rapid adhesion of platelets to the endothelium and basal lamina's exposed collagen. Involves Von Willebrand factor which promotes aggregation and activation.
181
Explain platelet aggegation in the platelet phase?
Adhesion leads to aggregation of the platlets together,.
Stimualted by soluble factors:
-ADP, thromboxane A2, Calcium and is positively feed back.
Inbited by:
-prostocyclin, Nitric oxide from in tact endothelium, Aspirin.
182
Explain platelet activation?
Shape change, by granulolysis secrete:
Thromboxane A2, calcium, ADP, Clotting factors e.g. PF3 (platlet factor 3).
Causes the aggregation.
183
What is the coagulation phase? Two pathways?
Where a fibre mesh is made to stabilise the clot and a cascade of enzyme reactions happen.
two pathways:
Extrinsic and Intrinsic.
184
What happens in the exrinsic pathway of the coagulation phase?
Tissue Damage > Tissue factor relseased, which activates factor X by the addition of Ca and clotting factor VII.
Fast pathway.
Finally leads to fibrilin stabilising factor
185
WHat happens in the intrinsic pathway of the coagulation phase?
collagen triggers activation of proenzymes which activates factor X
186
What does factor X do?
Causes prothrombin to cleave into thrombin, which turns fibrinogen into fibrin, which stabilises the blood clot.
187
How is a thrombus prevented?
inhibit thrombin using antithrombin III.
Natural anticoagulants e,g. heparin, thrombomodulin or prostacyclin.
Thrombotic drugs e.g. aspirin, warfarin
188
WHat is fibrinolysis?
enzyme breakdown of the fibrin in blood clots so can dissolve them.
189
Steps to clot breakdown?
endothelial cells release Tissue plasminogen activator TPA) which activates plasminogen which activates PLasmin and digests the fibrin strands.
190
what are the 4 types of haemophilia?
Type A: Factor VIII (8) defect, x linked
Type B: Factor IX (9) defect, x linked
Type C: Facor XI (11) defect, autosomal recessive.
Aquired haemophilia from an autoimmune disease.
