cardiovascular system-blood: platelets (thrombocytes)

Question 1

Thrombocytes (platelets) fragment in the

Answer 1

bone marrow into small fragments, platelets which pass in the blood

Question 2

thrombocytes (platelets) are destroyed by

Answer 2

phagocytes in the spleen

Question 3

thrombocytes (platelets) are mainly stored in the

Answer 3

spleen and are released during bleeding

Question 4

what is thrombocytopenia

Answer 4

low platlet count
due to less platelet production or excessive platelet destruction

Question 5

what is thrombocytosis

Answer 5

due to accelerated production of platelets in response to infections, inflammation, or cancer

Question 6

thrombocytopoiesis is the production of

Answer 6

thrombocytes

Question 7

thrombocytopoiesis
pleuripotent stem cells in the red bone marrow–>

Answer 7

megakaryoblasts–> megakaryocytes (form membranes, enzymes, proteins)–> thrombocytes (by shedding cytoplasm)

Question 8

pleuripotent stem cells in the red bone marrow stimulated by

Answer 8

Interleukins form megakaryoblasts which will form megakaryocytes

Question 9

hormonal controls:

Answer 9

1. thrombopoietin (TPO)
2. Interleukin-6 (IL-6)
3. Multi-CSF

Question 10

hormonal controls:
1.thrombopoietin (TPO)

Answer 10

accelerates platelet production and stimulation productions of megakaryocytes

Question 11

Hormonal Controls
2.Interlekin-6 (IL-6)

Answer 11

stimulates platelet formation

Question 12

hormonal controls
3.Multi-CSF

Answer 12

formation and growth of megakaryocyte

Question 13

megakaryocytes produce

Answer 13

structural proteins, enzymes, and membranes

Question 14

megakaryocytes shed cytoplasm in

Answer 14

small packets and form spindle shaped platelets

Question 15

functions of thrombocytes:

Answer 15

initiate and control the clotting process by releasing chemicals important to the clotting process

they clump together at the site of injury by forming a platelet plug

reduce the size of a break in the vessel wall

after a blood clot the platelet filaments contract to shrink the clot

Question 16

hemostasis and blood coagulation phases

Answer 16

1. vascular phase, vascular spasm
2. platelet phase
3. coagulation phase

Question 17

1. vascular phase, vascular spasm is the constriction of

Answer 17

blood vessels

Question 18

2. platelet phase is the formation of

Answer 18

platelet plug

Question 19

3. coagulation phase is the formation of a

Answer 19

blood clot (coagulation)

Question 20

hemostasis is a complex cascade in which

Answer 20

many things happen at the same time, interacting together

Question 21

1. vascular phase

Answer 21

lasts 30 minutes

the trauma of the vessel causes the vessel to contract to reduce the flow of blood from the vessel rupture

for smaller vessels, platelets release vasoconstrictor substance, thromboxane A2

Question 22

vascular phase happens in 3 steps

Answer 22

1. the endothelial cells contract and expose the basement membrane to the blood stream
2. endothelial cells release chemical factors ADP, tissue factor, local hormones, prostacyclin, and peptide hormones, endothelins

they in together accelerate smooth muscle contraction and cell division

3. endothelial plasma membranes become sticky and stick together preventing blood flow

Question 23

2. platelet phase

Answer 23

after injury, it begins within 15 seconds

when platelet come in conduct with a damaged vascular surface, e.g. exposed collagen fibers

to basement membranes

to sticky endothelial surfaces,

they adhere to collagen and is known as platelet adhesion

Question 24

platelets secrete:

Answer 24

1. ADP, stimulates platelet aggregation and
2. thromboxane A2 and serotonin- stimulate vascular spasm
3. clotting factors
4. platelets derived growth factor- promotes vessel repair
5. calcium ions which activate more platelets and stick them to the originally activated platelets, thus forming a platelet plug blocking the blood loss

Question 25

formation of platelet plug

Answer 25

injured tissue—>exposure of subendothelial cells—>vasoconstriction–> platelets aggregate and form a “plug”

injured tissue–>exposure of subendothelial cells–> platelets adhere to exposed cells–> platelets aggregate and form a “plug”

Question 26

3. coagulation phase

Answer 26

begins 30 sec or more after the injury
has 3 steps

Question 27

3 steps of the coagulation phase

Answer 27

1. in response to rupture of a vessel, a complex of activated substances called prothrombin activator is produced
2. the prothrombin activator catalyzes the conversion of prothrombin in to thrombin
3. the thrombin convert soluble fibrinogen into insoluble fibrin fibers which form a mesh to trap platelets, blood cells and plasma to form the clot

Question 28

blood coagulation

Answer 28

more than 50 important substances affect blood coagulation

some promote coagulation called procoagulants and others inhibit coagulation called anticoagulants

in the blood anti-coagulants pre-dominate so that blood does not coagulate in the blood stream

but when a vessel is ruptures procoagulants become activated

Question 29

factors that limit the growth of the platelet plug

Answer 29

1. prostacyclin: released by endothelial cells, inhibit platelet aggregation
2. inhibitory compounds released by other WBCs
3. circulating enzymes break down ADP
4. negative (inhibitory) feedback from serotonin
5. development of blood clot isolates area

Question 30

clotting factors (procoagulants)

Answer 30

proteins or ions in plasma
required for normal clotting
3 pathways

Question 31

the factors released by platelets and endothelial cells and clotting factors interact through either:

Answer 31

extrinsic pathway
intrinsic pathway
common pathway to form the clot

Question 32

the extrinsic pathway

Answer 32

begins in the blood vessel
outside bloodstream

1. damaged cells release tissue factor (TF)
2. when Ca2+ is present, forms complex with factor VII–> activated factor VII
3. activating factor X

Question 33

intrinsic pathway

Answer 33

within bloodstream

1. activation of factor XII exposed to collagen fibers
2. stimulates factor XI, activates IX, stimulates factor VIII, activates VIII platelet phospholipids, and Ca2+ to activate factor X

Question 34

____ pathway is shorter and faster than ____ pathway and initiates clotting first

Answer 34

Extrinsic pathway is shorter and faster than
intrinsic pathway and initiates clotting first.

Question 35

the common pathway

Answer 35

it starts with activated factor X from either pathway

activated factor X activates prothrombin factor

Question 36

prothrombin is a

Answer 36

plasma protein which is formed continually by the liver

Question 37

Vitamin ___ is necessary for the formation of ___ and clotting factors ___, ___. __, and __

Answer 37

Vitamin K is necessary for the formation of
prothrombin and clotting factors II, VII, IX and X.

Question 38

activated factor X

Answer 38

1. prothrombin activator
2. converts prothrombin into thrombin
3. thrombin converts soluble fibrinogen into insoluble fibrin—>forms a mesh–>trap blood cells —>clot