hemostatis within blood and hematology

Question 1

what makes up the cardiovascular system?

Answer 1

heart, blood vessels, and blood

Question 2

what is hemostatsis? when does it occur? what is it triggered by?

Answer 2

stoppage of bleeding
occurs in responce to blood vessel damage
triggered by chemicals released or activated by damaged cells and platelets

Question 3

what is the function of hemostasis?

Answer 3

functions to prevent blood loss and build a framework for tissue repair

Question 4

what are the three phases within hemostasis?

Answer 4

vascular phase
platelet phase
coagulation phase

Question 5

what is the vascular phase?

Answer 5

a vascular spasm of damaged vessels which causes constriction
smooth muscle contracts to reduce blood flow

Question 6

what do the endothelial cells lining the blood cells release in the vascular phase?

Answer 6

endothelial cells release endothelians which are peptide hormones

Question 7

what do the endothelins stimulate/make?

Answer 7

stimulate contraction of smooth muscle in blood vessel wall
stimulate division and repair
make endothelium sticky

Question 8

what is the platelet phase?

Answer 8

platelets adhere to collagen fibres which are exposed when endothelium are damaged
platelets aggregate as platelets become sticky
results in formation of a platelet plug

Question 9

what does platelet adhesion/aggregation activate?

Answer 9

the platelet

Question 10

what do activated platelets release?

Answer 10

chemicals and granules which contain many substances

Question 11

what substances do the granules contain?

Answer 11

serotonin - stimulates vascular spasm
thromboxane- stimulates platelet aggregation
PDGF- platelet derived growth factor, promotes vessel repair
Ca++ - promotes coagulation

Question 12

how is platelet aggregation an example of positive feedback?

Answer 12

as more platelets aggregate, more chemicals are released, attracting more platelets.

Question 13

what is coagulation?

Answer 13

blood clotting or blood goes from liquid to gel

Question 14

what does the coagulation phase result in?

Answer 14

formation of a clot

Question 15

what is a clot?

Answer 15

a tangle of fibrin (fibrous proteins) and cell

Question 16

what triggers clot formation?

Answer 16

triggered by sequential activation of clotting factors

Question 17

how do clotting factors circulate in what form?

Answer 17

circulate as inactive procoagulants and must be activated for coagulation to occur

Question 18

how are clotting factors numbered?

Answer 18

I thought XIII in order of discovery

Question 19

where are most clotting factors made?

Answer 19

made in the liver

Question 20

steps in coagulation?

Answer 20

1. vascular spasm
   (smooth muscle in blood vessel wall contracts)
2. platelet plug form
   (platelets stick to collagen in exposed vessel wall and platelets stick to each other
3. activation of platelet
   (platelets are activated by collagen and by chemicals released by aggregating platelets and by chemicals released by damaged cells)
4. coagulation
   (a cascade of activation of clotting factors in the blood causes a network of fibrin to form, trapping proteins and cells = clot)

Question 21

what is the intrinsic pathway ?

Answer 21

initiated within blood

Question 22

what triggers the intrinsic pathway?

Answer 22

triggered when clotting factors XII and platelets are activated by collagen

Question 23

what does the intrinsic pathway require?

Answer 23

requires platelet phospholipid which is expressed when platelets exposed to collagen( collagen is a c.t and walls of torn blood vessels)

Question 24

when can the intrinsic pathway occur?

Answer 24

can occur when blood is exposed to glass, a negatively charged surface which has the same effect as collagen (eg blood in a test tube)

Question 25

how long does the intrinsic pathway take?

Answer 25

slow about 2-3 min

Question 26

what is the extrinsic pathway initiated by?

Answer 26

intitiated by chemicals external to the blood

Question 27

how is the extrinsic pathway activated?

Answer 27

activated by a chemical released by damaged cells

Question 28

what do damaged cells release?

Answer 28

they release TF which is tissue factor/thromboplastin which activates platelets

Question 29

how long does the extrinsic pathway take?

Answer 29

faster under 2 minutes

Question 30

what does both pathways activate?

Answer 30

both activate clotting factor X which initiate the common pathway which results in network of fibrin