Hemostasis - Karius

Question 1

Hemostasis

Answer 1

Steps taken by the body to limit blood loss

Question 2

4 Steps of hemostasis

Answer 2

1. vascular spasm
2. formation of a platelet plug
3. formation of a blood clot
4. repair of damage

Question 3

Platelet

Answer 3

Cell fragment from megakaryocyte

150000-300000/um3 normal range

Question 4

Production of platelets

Answer 4

Thrombopoietin

Question 5

Thrombopoietin

Answer 5

TPO
Protein hormone
Chr 3
JAK2/STAT5
Amine terminal is like erythropoietin (EPO)
Carboxyl end: prolongs half-life
Produced by liver, kidney

Question 6

Control of thrombopoietin secretion

Answer 6

Continually secreted

Platelets bind thrombopoietin (mpl) receptor

Question 7

Thrombopoietin binds to

Answer 7

mpl (CD-110) receptor

Question 8

High number of platelets and thrombopoietin secretion

Answer 8

Lots of TPO bound to mol receptor on platelets
Internalize TPO and destroy it
Not much free to act on megakaryocytes

Question 9

Low number of platelets and thrombopoietin secretion

Answer 9

Little bound to platelets
Not being destroyed
Lots free

Question 10

Main fxn thrombopoietin

Answer 10

Increase differentiation of stem cells and maturation rate

All cell lines

Question 11

Mutation in TPO receptor

Answer 11

Cause polycythemia vera

Question 12

Polycythemia vera

Answer 12

Platelets unable to internalize and destroy the TPO so is action becomes continuous

Question 13

Platelets have actin and myosin

Answer 13

Cell contraction

Empty vesicles

Question 14

Platelets contain

Answer 14

Actin and myosin
Mitochondria
Remnants of the ER
Cyclooxgenase
Fibrin stabilizing factor
Platelet-derived growth factor
Serotonin (5-HT)

Question 15

On platelet membrane

Answer 15

Glycoproteins
Phospholipids
Receptors for collagen

Question 16

Platelet glycoproteins

Answer 16

When activated, sticky

Question 17

Platelet phospholipids

Answer 17

Platelet factor 3

Question 18

Primary causes of vascular spasm

Answer 18

Myogenic

Platelet factors

Question 19

Myogenic causes of vascular spasm

Answer 19

Direct response to injury

No neurons, reflexes involved

Question 20

Platelet causes of vascular spasm

Answer 20

Serotonin

Thromboxane A2

Question 21

Factors contributing to the vascular spasm

Answer 21

A neural reflex initiated by the mechanical injury and pain
–neither necessary or sufficient for spasm to occur
MINOR

Question 22

Formation of platelet plug

Answer 22

Damage to vessel wall and collagen is exposed
Platelets will bind to collagen
Von Willebrand factor
Binding of platelet receptor (integrin) to collagen

Question 23

Von Willebrand factor

Answer 23

Plasma protein

Bind between collagen and platelet (receptor)

Question 24

Activation of platelet

Answer 24

Platelet swells

Extend podocytes

Question 25

Last steps of formation of platelet plug

Answer 25

Platelets swell Contraction Granules leave platelet Platelets stick to vessel wall and to each other (thromboxane A2 and ADP)

Question 26

If cut is small enough

Answer 26

Platelet plug may be all that is required

Question 27

3 essential steps for blood coagulation

Answer 27

1. Formation of prothrombin activator 2. Activation of thrombin 3. Creation of fibrin from fibrinogen

Question 28

Clot retraction

Answer 28

``` Get rid of excess fluid within clot Solidify clot Platelets required -bind fibrin polymer together -actin and myosin in platelet - contraction Also requires calcium ```

Question 29

Blood clot parts

Answer 29

Platelets RBCs Fibrin strands

Question 30

Platelets are required

Answer 30

To stabilize the clot and cause clot retraction

Question 31

Platelet-derived growth factor

Answer 31

Secreted by platelets Stimulate fibroblast to grow into area Fibroblasts differentiate into smooth muscle to close the hole

Question 32

Plasminogen

Answer 32

Made by liver Floating in plasma Not active form

Question 33

Activation of plasminogen

Answer 33

Tissue plaminogen activator

Question 34

Tissue plaminogen activator

Answer 34

Released by damaged tissue | Activation is inhibited by tPA inhibitor (blood)

Question 35

tPA can convert

Answer 35

plasminogen to plasmin

Question 36

Plasmin

Answer 36

Breaks down fibrin to remove the clot

Question 37

How do blood vessels prevent clotting?

Answer 37

Smooth surface - prevent platelets from rupturing | Membrane proteins - glycocalyx and thrombomodulin

Question 38

Glycocalyx

Answer 38

Membrane protein that repels platelets (prevent clotting)

Question 39

Thrombomodulin

Answer 39

Membrane proteins that changes thrombin activity to prevent clotting

Question 40

4 Chemicals that limit clotting

Answer 40

Fibrin - binds thrombin Prostacyclin Antithrombin III Heparin

Question 41

Fibrin

Answer 41

Binds thrombin and prevents it from working

Question 42

Prostacyclin

Answer 42

Made at time of injury by endothelial cells Vasodilation Limit platelet aggregation

Question 43

Antithrombin III

Answer 43

When thrombin binds to it, works as anticoagulant

Question 44

Heparin

Answer 44

Derived from mast cells | Increases antithrombin efficacy

Question 45

When Protein C is activated

Answer 45

Inactivated factors V and VIII

Question 46

Thrombocytopenia

Answer 46

Platelet plug failure

Question 47

Cause of thrombocytopenia

Answer 47

Stem cell damage Leukemia TPO or mpl gene mutation

Question 48

Platelet count for spontaneous bleeding

Answer 48

< 25,000

Question 49

Vitamin K deficiency

Answer 49

Fat soluble vitamin made by gut bacteria Required for production of prothrombin and 3 other factors Neonates are often K deficient (no gut bacteria yet) Any thing that impairs absorption of fats can render an adult deficient

Question 50

Hemophilia

Answer 50

Genetic absence of a clotting factor | Most common Factor VIII

Question 51

Most common hemophilia

Answer 51

Factor VIII def

Question 52

vonWillebrands disease

Answer 52

Congenital absence of vWF | Impairs both platelet function and clot production

Question 53

Acquired forms of impaired clotting include:

Answer 53

Thrombocytopenia | Vit K deficiency

Question 54

Causes of inappropriate clotting

Answer 54

``` Blood vessels have rough surface Blood stasis (slow moving) Disseminated intravascular coagulation ```

Question 55

Protein C total absence

Answer 55

Severe pro-thrombotic state, child dies in infancy

Question 56

APC resistance

Answer 56

Leiden mutation (single point mutation) Factor V mutated Cannot be inactivated by APC First signs often in young adulthood, particularly pregnancy

Question 57

Clinical relevance of APC resistance (protein C)

Answer 57

1% US population will experience thrombosis Of them, 64% have some form of APC resistance Effects vary