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Flashcards in Karius Hemostasis Deck (50)
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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