Pathology - Circulation Flashcards

1
Q

What lines the lumen of blood vessels?

A

endothelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is around the basal lamina of blood vessels?

A

smooth muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is around the smooth muscle in blood vessels?

A

interstitial collagen fibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does the lumen of blood vessels contains?

A
  • red blood cells
  • white blood cells
  • platelets
  • plasma
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does plasma consist of?

A

water, proteins, other solutes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does plasma contain?

A

clotting factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where are many clotting factors mainly produced?

A

in the liver but also by endothelial cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are clotting factors?

A

an amplification system, resulting in thrombin production

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does thrombin do?

A

converts soluble fibrinogen into insoluble fibrin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does fibrin do?

A

forms a mesh of strands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Simplified clotting cascade

A

damage → TF + prothrombin → thrombin + fibrinogen → fibrin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is meant by initial damage in the clotting cascade?

A

one obvious is trauma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does trauma lead to?

A
  1. exposure of interstitial collagens (collagens in connective tissue between structures)
  2. exposure of a molecule called tissue factor (TF)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is tissue factor released from?

A

smooth muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What does “many clotting factors are serine proteases” mean?

A

that clotting factors have a serine amino acid in them and they cleave other clotting factors to form the active molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Where are platelets produced?

A

in bone marrow from a cell called megakaryocyte

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is a megakaryocyte?

A

large cell with many nuclei

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How do platelets work

A

trauma to vessel → exposure of platelets to interstitial collagen → platelets adhere together and try to form bridge to close gap

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is coagulation

A

Solidification of blood (clotting)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the 2 types of coagulation

A
  1. Thrombus formation

2. Clot formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Where does thrombus formation occur

A

In flowing blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Describe a pure thrombus

A
  • Pale cream coloured

- Consists of platelets and a mesh like network of fibrin strands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is thrombosis

A

The process of thrombus formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Why does a thrombus of platelets and fibrin occur in flowing blood?

A

platelets have molecules on their surfaces which allows adherence to interstitial collagen ever when blood is flowing past them - the clotting cascade deposits factor VIII which enhances this further

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Where does clot formation occur?
Blood leaks out of a vessel and becomes stationary (stagnant)
26
Describe clot formation
Wishing the stagnant blood, sitting next to interstitial collagen, the clotting cascade is activated A clot consists of a network of fibrin strands and red blood cells
27
What is haemostasis
Stopping bleeding
28
What is the role of vasoconstriction in bleeding
Helps reduce bleeding
29
How is thrombus removed?
A blood protein called plasminogen converts to plasmin, and plasmin cuts up fibrin into smaller fragments as a way of removing fibrin. In a thrombus this is sometimes called thrombolysis
30
What does the fibrinolytic system depend on?
- Plasma protein called plasminogen being converted to plasmin - Plasmin cuts up fibrin into fibrin degradation products
31
What are the 3 main causes of thrombosis (virchow's triad)
(1) venous stasis, (blood not moving) (2) activation of blood coagulation, (3) vein damage
32
Example of pathological thrombosis -coronary artery thrombosis
- coronary arteries are the main arteries in the heart and supply the heart muscle - smoking cigarettes increases the stickiness of platelets (find it easier to aggregate) - stickier platelet makes it more likely that a thrombosis will occur - this alteration in the properties of blood is a change in blood constituents which is part of Virchow's triad - cigarette smoking can also predispose to atheroma in the coronary arteries - atheroma can occur and slowed blood flow predisposes to fibrin and platelet clumping - this is an example of a change in the pattern of blood flow which is part of Virchow's triad - lipid can also rupture through the intimal surface which is a change in the intimal surface, also part of Virchow's triad
33
What is atheroma?
a disease of coronary arteries which results in a build up of lipids under the intimal surface
34
What can atheroma result in?
the lipid can result in abnormal blood flow - can get both slow and turbulent flow
35
Describe the lines of Zahn
arterial thrombus - multiple layers of thrombus and clot (pale layers of thrombus alternating with red layers of clot)
36
What does complete obstruction by thrombus blocking an artery lead to?
No flow beyond the blockage
37
What does partial obstuction by thrombus blocking an artery lead to?
Decreased blood flow beyond the blockage
38
What is ischaemia
Poor blood flow
39
Describe the consequences of ischaemia
- If it is severe enough can lead to decreased oxygenation of tissues - The tissue is said to be 'ischaemic' - Ischaemic heart tissue is often painful
40
What is hypoxia?
Decreased oxygenation of tissues
41
What is an infarct?
A localised area of dead tissue as a result of Ischaemia
42
What is coronary artery thrombosis
Infarct in heart | myocardial infarction
43
What is cerebral artery thrombosis
Infarct in brain
44
What is an embolism
A mass of material moves in the vascular system and bale to become lodged in a vessel and block its lumen
45
What are most emboli derived from?
Thrombi or clots
46
What do emboli do?
Break off and go elsewhere in the circulation
47
What is thromboembolis?
When thrombi/clots embolise
48
How does a pulmonary embolism occur?
- Sluggish flow in leg veins lead to thrombosis and clot formation - Part of thrombus breaks off and travels up vein - Embolus passes into inferior vena cava, then the right heart. then pulmonary artery bench - Embolism block pulmonary artery and get pulmonary infarct
49
Provide an example of marrow embolism
fracture a leg -> marrow enters ruptures -> air embolisms to lung vessels
50
Examples of air embolism
Knife wound to neck -> air enters vein -> marrow embolisms to lung vessels
51
What is circulatory shock?
Profound circulatory failure causing poor perfusion of vital organs
52
What does shock mean in practice?
Low blood pressure in physiological consequences
53
What does normal blood pressure rely on?
Enough blood in the system Smooth muscle in vessels having a certain 'tone' heart pumping blood
54
What is normal blood pressure(arterial)
120/80
55
What happens if smooth muscle tone is decreased?
The vessel will dilate, if enough vessels new affected then blood pressure may fail
56
There are ____ carotid bodies and ___ carotid sinuses on either side of the neck
2,2
57
What do the 2 carotid bodies consist of?
Groups of cells which sense the partial pressure of oxygen
58
What do the carotid sinuses do if blood pressure drops?
They send nerve signals to the brain stem which then tells the heart to pump harder and faster via nerve signals
59
What is the physiological response to low blood pressure?
Faster pulse
60
In practice circulatory shock is present if:
- Low blood pressure combined with fast pulse
61
What are the 3 main causes of circulatory shock
1. hypovolaemic 2. septic 3. cardogenic
62
Describe hypovolaemic shock
Low blood pressure reflects severe reduction in amounts of blood in circulation High pulse reflects physiological response to low blood pressure
63
Describe some of the complications of shock
- Decreased perfusion of brain -> initially reversible but then permanent - Decreased perfusion of kidneys -> initially reversible, then more severe