Module 3 Platelets

Platelets

cell fragments derived from Megakaryocytes

What are the functions of Platelets

sticky, adhere to site of damage blood vessels

forms platelet plugs that seal ruptured area

5 chemicals in platelet clotting process

1. serotonin

2. ADP

3. Calcium

4. enzymes

5. platelet dervied growth factors

thrombopoietin

platelet formation regulation

what 2 things makes platelets inactive

nitric oxide and prostacyclin

Platelets formed in where

myeloid cell line. Megakaryoblast

Hemostasis

series of fast reaction to stop bleeding

3 steps of Hematosis

1. vascular spasm

2. platelet plug formation

3. coagulation (blood clotting)

step 1 of hematosis

vascular spasms trigger by

direct injury to vascular smooth muscle

chemicals released by endothethial cells and platlets

pain reflexes

step 2 of hematosis

platelet plug formation

platelets stick to collagen fibers, when exposed to damage

step 2 of hematosis

what is von willebrand factor

stabilize platelet collagen adhesion

Step 2 of hematosis

plates swell becoming spiky and sticky. what 2 chemicals messengers are released

ADP and serotonin

what type of feedback if platelet formation

positive feedback.

remember positive escalating to fix the body

negative feedback, a loop to restore balance

hemostasis step 3

coagulation

blood clotting

Hematosis step 3 coagulation:

what is phase 1 of coagulation:

2 pathways of thrombin activators

triggered by intrinsic and extrinsic pathways (usually both)

Hematosis step 3 coagulation

2 pathways: what is the intrinsic pathway

triggered by?

Called “intrinsic” because clotting factors are present within the blood

triggers: collagen exposure

Hematosis step 3 coagulation

2 pathways: what is the extrinsic pathway?

triggered by?

Called “extrinsic” because factors needed for clotting are located outside blood

trigger: eposure to tissue factor (TF) comes contact with blood

Hemostatis step 3: Coagulattion

what is phase 2?

pathway to thrombin

Hemostatis step 3: Coagulattion

what is phase 3?

common pathway to the fibrin mesh