Karius Hemostasis Flashcards Preview

Cardiopulmonary Exam 1 > Karius Hemostasis > Flashcards

Flashcards in Karius Hemostasis Deck (50):
1

Hemostasis

the steps taken by the body to limit blood loss, but hemostasis is NOT confined only to the blood clot

2

Hemostasis four steps

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

3

TPO

thrombopoietin (TPO)
protein hormone with an amine terminal similar to erythropoietin (EPO) but unique carboxyl terminal
TPO stimulates megakaryocytes to produce platelets


made by liver and kidney

in liver, the parachymal sinusoidal cells
in the kidney, the proximal convoluted tubules
stimulus for its release is uncertain

4

EPO

erythropoietin TPO
produced in liver, stimulates red blood cell production in the bone marrow in response to hypoxia

produced by liver and kidney

5

Platelet production control

they bind thrombopoietin to their mpl receo

6

mpl receptors

found in platelets, megakaryocytes, and other hematopoietic cells

utuilized Jak/Stat and phosphorylation, subsequent transcription and translation of various genes

7

a high number of platelets indicates

lots of TPO bound to the mpl receptors. they internalize signal and destroy it.

not much free to act on megakaryocytes

not much free TPO in the body or to act on megakaryocytes

8

low number of platelets indicates

small amount of TPO bound to platelets; TPO is not being destroyed

there's LOTS of TPO free in the blood

9

TPO increases

increases differentiation of stem cells and maturation rate/

effects on all cell lines

10

megakaryoblast --> ______ ---> ____

megakaryocyte, platelet (thrombocytes)

11

TPO acts on

all cell lines in the body

12

polycythemia vera

mutation in TPO receptor
, platelets unable to internalize and destrou TPO so its actions become continuous

13

platelet internal mechanisms (7 things)

actin and myosin for cell contraction and emptying vesicles
mitochondria for ATP and ADP

remnant of the ER (for calcium storage)
COX1 (prostaglandin production
Cox1 produces thromboxane A2

Fibrin Stabilizing Factor (clot stability)
Platelet derived growth factor (repair)
Serotonin

14

Platelet membrane becomes ____ when activated. It also contains important ________ and receptors for ______

sticky, phosholipids, collagen

15

If platelet levels drop, what happens to TPO

their quantity increases, so they can act

16

If platelet levels increase, what happen to TPO

their quantity decrease, and their destruction marks them off from acting

17

What cell lines does TPO act on?

all cell line

18

Erythropoiesis vs Thrombopoiesis

What is their respective sources?

Ery - kidneys and liver
Thrombo - liver

19

what triggers EPO and TPO release?

EPO: low oxygen
TPO: constitutive (constant)

20

Control of EPO and TPO hormones, respectively

EPO: Hypoxia Inducible Factor (HIF) accumulation in renal cells

TPO: internalization/destruction of TPO

21

Receptors for EPO and HPO release

EPoR and MPL

22

Cells that express receptors for EPO vs HPO

EPoR expressed by pluripotent stem cell, RBC precursors
MP: pluripotent stem cells, platelets, all hematopoietic cell lines

23

Erythropoietin's effect

causes daughter cells in Erythroid cell line to undergo mitosis

24

Thrombopoietin's effect

increases division and maturation of all blood cell lineages

25

Hemostasis: step 1

MYOGENIC spasm induces vascular occlusion.
occurs spontaneously in response to injury, no neurons or reflexes involved

26

Platelet factors include

serotonin and thromboxane A2 contribute to spasm

27

"contributing factors" to the vascular spasm (step 1 of hemostasis)

neural reflex from nociceptors (mechanical response)

not sufficient or necessary for spasm to occur, minor contribution

28

Hemostasis Step 2: overview of steps

formation of the platelet plug followed by binding of platelets to exposed collagen (two step process)

29

Hemostatic plug formation step 2: platelet activity

a. binds to exposed collagen at site of injury using VWF

1. uses Von Willebrand Factor
2. plasma protein
3. bind between collagen and platelet receptor

b. platelet integrin receptor binding to collagen

30

during the second phase of a hemostatic plug formation, what do platelets do upon activation?

1. swell and extend podocytes
2. contraction
3. granules leave platelet
4. platelets stick to vessel wall and each other

31

What do thromboxane A2 and ADP do

they are released during self aggregation of platelets

32

Hemostasis Step 3: role and steps

blood coagulation

1. formation of prothrombin activator
2. thrombin activation
3. conversion of fibrinogen to fibrin

leading to CLOT RETRACTION

33

Hemostasis step 3: Clot Retraction

This step gets rid of excess fluid in the clot to solidify it.
Platelets are required (to bind fibrin together, as well as their actin/myosin platelet contractions)
also requires calcium

34

Hemostasis step 4

Repair of damage

Repair of damage

Platelet secretion of Platelet derived fibroblast growth factor

stimulates fibroblasts to grow into area

fibroblasts grow into smooth muscle etc to close the hole

35

Getting rid of the clot

achieved by plasminogen
floating freely in blood

tPA: tissue plasminogen activator, released by damaged tissues.

tPAi: inhibits tPA, in the blood

36

Thrombomodulin is located on the

endothelial cell, and bind thrombin

37

Thrombomodulin activates thrombin on the endothelial cell: what does it activate

Protein C, which inactivates tPAi, allowing tPA to activate Plasminogen from zymogen form: Plasminogen ---> Plasmin

plasmin lysis fibrin

38

Prevention of Clotting: the role of smooth surfaces

prevents platelets from rupturing


39

Prevention of clotting: the role of membrane proteins

endothelial cell glycocalyx repels platelets
thrombomodulin activates thrombin

40

Chemicals which limit clotting (4)

1. Fibrin: binds thrombin and prevents it working
2. Prostacyclin (PG12) made by injured cells, limits platelet aggregation
3. Antithrombin III: binds and prevents thrombin from working
4. Heparin: made from mast cells, increases efficacy of antithrombin

41

Protein C

Inhibits tPAi AND inactivates the VIIIa--Va complex responsible for activating prothrombin

42

what is the outcome of TPO being internalized by platelets?

they are destroyed, so they cant stimulate other hematopoietic cell lines

43

mpl biochemical pathway

JAK/STAT

JAK2 activated ---> STATs 1, 3, 5 activated (Stat 1/3 dimerize, stat 5 homodimerizes

44

TPO actions on megakaryocytes, platelets, and other hormone interactions

causes SIZE and NUMBER of megakaryocytes to increase

causes platelet specific markers to develop

stimulates endomitosis and polyploidy of megakaryocytes

works with erythropoietin to stimulate RBC production
works with IL-3, or Steel Factor to upregulate RBC and WBC factors to differentiate

45

Platelets: actin and myosin?

just like in skeletal muscle, they have cross bridges that undergo cycling causing contraction of the cell

they help SQUEEZE extra fluid out of clot

help empty vesicles

46

Cyclooxygenase (COX 1)

enzyme that catalyzes production of thromboxane A2. prostaglandins

47

Fibrin Stabilizing Factor

XIII, causes covalent bonds to form between fibrin monomers

48

platelet derived growth factor

aids in repair of damaged tissue

49

what does Thromboxane do exactly?

binds to GPCR on smooth muscle and triggering calcium release

causes an increase in IP3

causes release of calcium from intracellular stores of the smooth muscle cell

50

how is the platelet held in place during clot formation?

two points of contact: von willebrand factor between collagen and platelet, and integrins on the platelets interacting with the collagen