Hemostasis

Question 1

Hemostasis

Answer 1

Steps body takes to limit blood loss - clot formation

Question 2

What are platelets derived from?

Answer 2

Megakaryoctyes

Question 3

Platelets are ____ of megakaryocytes

Answer 3

Cell fragments

Question 4

Another name for platelets?

Answer 4

Thrombocytes

Question 5

What is the normal range of platelets?

Answer 5

150K - 450K

Question 6

Less than ____ platelets is lethal

Answer 6

10K

Question 7

What things do platelets contain?

Answer 7

1. Actin, myosin, mitochondria
2. Dense core granules and alpha granules
3. Cox1 - generates thromboxane A2
4. Serotonin

Question 8

What types of granules do platelets contain?

Answer 8

Dense core and alpha granules

Question 9

What neurotransmitter do platelets contain?

Answer 9

Serotonin

Question 10

What molecule regulates platelet production?

Answer 10

Thrombopoietin (TPO)

Question 11

What produces Thrombopoietin?

Answer 11

Kidney and Liver

Question 12

What receptor does Thrombopoietin bind to?

Answer 12

C-MPL

Question 13

What cells contain C-MPL receptors?

Answer 13

Megakaryocytes/platelets/other hematopoietic stem cells

Question 14

When TPO binds to C-MPL receptor on megakaryocytes, what results?

Answer 14

Formation of platelets

Question 15

What happens to TPO when there is a high number of platelets?

Answer 15

It is mostly bound to C-MPL receptor and then gets internalized and degraded by megakaryocytes and platelets

Question 16

What happens to TPO when there is a low number of platelets?

Answer 16

It is mostly free and NOT bound to C-MPL

Question 17

What controls the secretion of Thrombopoietin?

Answer 17

Itself and platelets

Question 18

What are the steps to Hemostasis?

Answer 18

1. Vascular spasm (vasospasm)
2. Formation of platelet plug
3. Clot formation

Question 19

What platelet factors are involved in vasospasm?

Answer 19

Serotonin and Thromboxane A2

Question 20

Why don’t platelets adhere to each other?

Answer 20

Their NEGATIVE CHARGES

Question 21

Adhesion of platelets to the site of injury is initiated by the activation of?

Answer 21

Platelet receptors

Question 22

What receptor on platelets stimulates platelet adhesion through its activation?

Answer 22

GP 1b/1a

Question 23

What does GP 1b/1a bind to?

Answer 23

Von Willebrand Factor (vWF)

Question 24

After GP 1b/1a binds vWF and its activated, what does this cause?

Answer 24

Release of platelet contents:

- Release of ADP, serotonin, thromboxane A2, Fibrinogen, vWF

Question 25

Release of platelet contents causes?

Answer 25

Activation and aggregation of more platelets

Question 26

What receptor on platelets does ADP bind?

Answer 26

P2Y12

Question 27

Once fibrinogen is released, it binds platelet receptors to do what?

Answer 27

Bridge platelets together and forms the plug

Question 28

Release of what from activated platelets causes the plug to form?

Answer 28

Fibrinogen

Question 29

What is important in the formation of a clot?

Answer 29

Thrombin

Question 30

Thrombin takes fibrinogen to?

Answer 30

Fibrin

Question 31

Fibrin polymerization and contraction of the clot requires?

Answer 31

Calcium

Question 32

What does Aspirin inhibit?

Answer 32

Clot formation by inhibiting release of more thromboxane A2

Question 33

What does Clopidogrel (plavix) inhibit?

Answer 33

P2Y12 receptors on platelets to block further platelet activation

Question 34

When the platelets release ADP, serotonin, and thromboxane A2, what does that do?

Answer 34

Those molecules go on to bind more receptors on platelets which activates them and causes more platelets to aggregate at the injury site to form the platelet plug

Question 35

Aspirin and plavix reduce clot formation by blocking molecules that?

Answer 35

Stimulate more activation and aggregation of platelets