90. Haemostasis

Question 1

what is the purpose of haemostasis

Answer 1

stops bleeding, prevents blood loss, maintains vessel integrity

Question 2

when is haemostasis important

Answer 2

childbirth, surgery, trauma

Question 3

what are the 4 key processes of haemostasis

Answer 3

Vasoconstriction
Primary Haemostasis (platelet plug formation)
Secondary Haemostasis (Fibrin clot formation)
Fibrinolysis

Question 4

when injury occurs to the blood vessel the endothelial cells release what

Answer 4

Vasopressors

Question 5

can you name the 4 vasopressors

Answer 5

endothelin, prostaglandins, thromboxane A2, catecholamines

Question 6

when vasopressors are released by endothelium cells after injury what does this cause

Answer 6

reduction of blood flow to affected area

Question 7

changes of flow in the blood vessel causes and increase of what and why

Answer 7

increased margination of RBCs aas Platelets and WBCs are closer to the vessel wall

Question 8

what is margination

Answer 8

Margination is a process in which blood cells, particularly white blood cells (WBCs) and platelets, move to the periphery of the bloodstream and come into closer contact with the blood vessel walls. This typically occurs in smaller blood vessels and capillaries, especially under conditions of reduced blood flow or increased turbulence, such as during vasoconstriction

Question 9

vasoconstriction due to injury is a ‘Fast’ or ‘Slow’ process which is ‘Long lasting’ or ‘brief’

Answer 9

Fast and brief

Question 10

how do endothelial cells prevent platelet adhesion, aggregation and activation

Answer 10

○ 13-HODE
○ Prostacyclin
○ NO
○Ectonucleotidases

Question 11

what is platelet adhesion

Answer 11

the process by which platelets stick to the exposed surfaces of a damaged blood vessel. This is the first step in forming a platelet plug during primary haemostasis.

Question 12

what is platelet aggregation

Answer 12

Platelet aggregation is the clumping together of platelets to form a temporary plug at the site of vessel injury.

Question 13

what is platelet activation

Answer 13

the process by which platelets change shape, release chemical signals, and become sticky, which is essential for forming a stable platelet plug.

Question 14

What components work together to inhibit coagulation and prevent excessive clot formation:

Answer 14

Thrombomodulin: Reduces thrombin’s clotting ability and activates Protein C.
Heparin-like Molecules: Enhance antithrombin activity to inhibit thrombin and factor Xa.
TFPI: Inhibits the tissue factor pathway, reducing the activation of factor X and limiting the coagulation cascade.

Question 15

name the stages of a platelet cell

Answer 15

Hematopoietic stem cell
promegakaryocyte
megakaryocyte
platelet

Question 16

what is the life span of a platelet

Answer 16

7-10 days

Question 17

what is a normal platelet cell cound

Answer 17

150-400 x109/L

Question 19

where is collagen typically found

Answer 19

subendothelial layer aka the layer just beneath the endothelial cells lining the vessel

Question 20

When a blood vessel is injured, the endothelial cells are damaged, exposing the collagen underneath.
what happens?

Answer 20

Platelet Adhesion: Platelets in the blood recognize and stick to the exposed collagen. This is one of the first steps in forming the platelet plug

Question 21

what is the full name of vWF

Answer 21

Von Willebrand Factor

Question 22

what cells produce vWFs

Answer 22

endothelial cells and megakaryocytes (cells int the bone marrow that produce platelets)

Question 23

what do vWFs do in response to injury

Answer 23

vWF acts as a bridge between the platelets and the exposed collagen. It binds to specific receptors on the platelets and to the collagen, helping the platelets stick to the site of injury more effectively.

Question 24

vWF attach to …….. receptors on platelets

Answer 24

GPIb-IX-V