Platelets and Hemostasis

Question 1

Platelets are form by?

Answer 1

Fragmentation from megakaryocytes

Question 2

life span of platelets

Answer 2

degenerate in 10 days

Question 3

who stimulates production of platelets

Answer 3

Thrombopoietin

Question 4

What is hemostasis

Answer 4

Process of stopping bleeding.

Question 5

3 phases of hemostasis

Answer 5

1. Vascular spasms
2. Platelet plug formation
3. Coagulation (blood clotting)

Question 6

Coagulation also known as?

Answer 6

blood clotting

Question 7

vascular spasm role and function

Answer 7

Smooth muscle contracts causing vasoconstriction and causes blood
vessel to spasm, the spasms will narrow the blood vessel decreasing blood loss

Question 8

factor that trigger vascular spasm

Answer 8

▪ Direct injury to vascular smooth muscle
▪ Chemicals released by endothelial cells and platelets
▪ Reflexes initiated by local pain receptors

Question 9

Briefly describe the platelet plug formation

Answer 9

1) Damaged endothelium expose underlying collagen fibers

2) Platelets adhere (粘) to collagen fibers via von Willebrand factor

3）Anchored platelets release chemicals to attract more
platelets

4）Platelets pile (堆) up to form a platelet plug

Question 10

Two pathway for coagulation cascade

Answer 10

intrinsic pathway
extrinsic pathway

Question 11

what is required to activate both coagulation pathway

Answer 11

phospholipids

Question 12

what is coagulation cascade

Answer 12

Activation of a series of coagulation factors or clotting factors

Question 13

coagulation process in detail

Answer 13

1)Injured tissues release tissue factor (TF)

2) PF3 (a phospholipid) interacts with TF, blood protein clotting factors, and calcium ions to trigger a clotting cascade Involves clotting factors numbered I to XIII

3) Prothrombin activator coverts prothrombin to thrombin

4) Thrombin will joins fibrinogen proteins into hair-like molecules of insoluble fibrin

5) Fibrin forms a meshwork

Question 14

The clot is stabilized by a platelet-induced process called?

Answer 14

clot retraction

Question 15

As clot retraction is occurring, the vessel is healing, _________ stimulates smooth muscle cells and fibroblasts to divide and rebuild the wall

Answer 15

Platelet-derived growth factor (PDGF)

Question 16

________ stimulates endothelial cells to multiply and restore the endothelial lining

Answer 16

Vascular endothelial growth factor (VEGF)

Question 17

Fibrinolysis meaning

Answer 17

Removes unneeded clots after healing

Question 18

Plasmin function

Answer 18

act as a fibrin-digesting enzyme

Question 19

how to limit clot growth

Answer 19

Thrombin:
binds to fibrin threads, helping to form stable blood clots. Fibrin prevents clots from getting too big.

Antithrombin III:
stops extra thrombin from causing unwanted clots, while heparin boosts antithrombin III’s action, helping to prevent clot formation.

Question 20

why is antithrombic substance important in blood clotting

Answer 20

because it can prevent undesirable clotting by prevent platelet adhesion (粘附)

Question 21

What cause the undesirable clotting

Answer 21

thrombus and embolus

Question 22

How thrombus cause the undesirable clotting

Answer 22

if large enough it can obstruct the blood flow

Question 23

How embolus cause the undesirable clotting

Answer 23

It will break away from the vessel and floats freely in the bloodstream, may get stuck at the narrow blood vessels and cause a blockage

Question 24

low platelet count in the blood will cause?

Answer 24

Thrombocytopenia

Question 25

_____ cause by deficiency or dysfunction of certain blood clotting factors, specifically factor VIII

Answer 25

Hemophilia