Cardiovasular System Platelets Flashcards
Platelets is also called?
thrombocytes
What is the normal platelet count?
140,000 to 440,000
Platelets are ____ true cells but are ______ that are remnants of ________ cells called____
- not
- cellular fragments
- bone marrow
- megakaryocytes
immature cells that give rise to PLTs; differentiate from hemocytoblasts in red bone marrow
megakaryocytes
a hormone/hemopoietic growth factor produced by the liver that increases the rate of PLT production by stimulating the differentiation of myeloid stem cells to megakaryocytes
thrombopoietin
What is the shape of platelets?
irregularly disc-shaped
2-4 um
have many vesicles but no nucleus
short life span (5-9 days)
What is the main function of platelets?
blood clotting
the medical term for an abnormally low PLT count w/c indicates anrisk for bleeding
thrombocytopenia
is a sequence of responses that stops bleeding
hemostasis
stimulated in response to rupture or damage to blood vessels
hemostasis
refers to the loss of a large amount
of blood from the blood vessels
hemorrhage
In vascular spasm,
blood vessel damaged in traumatized tissue→PLTs in the area of the rupture release ______→smooth muscle in blood vessel wall _______ → vasoconstriction & _____→ blood flow to ruptured vessel
- serotonin
- contracts
- spasm
this process occurs immediately once blood vessel is damaged
Vascular spasm
this process occurs within seconds from damage to the blood vessel
Platelet Plug Formation
In platelet plug formation, platelets contact and stick to the damaged blood vessels. what process is this?
platelet adhesion
In platelet plug formation, platelets are activated and release _______ and ______. What is this process called?
Thromboxane A2 and ADP
the process is called platelet release reaction
In the third step of platelet plug formation, ADO and thromboxane A2 makes other platelets in the area _____that makes platelets adhere to the originally activated platelets.
what is the platelet gathering called?
- sticky
- platelet aggregation
Platelet aggregation then promotes the formation of _______
platelet plug
it is also called blood coagulation
blood clotting
a network of insoluble protein fibers called fibrin in w/c the formed elements of blood are trapped
clot
is a series of chemical reactions that culminates in formation of fibrin threads
blood clotting
blood clotting involves several substances known as _____
clotting factors
blood clotting lead to formation of?
fibrin threads
is thus a complex cascade of _____ in which each clotting factor activates many molecules of the next one in a fixed sequence
enzymatic reaction
The clot begins to develop within _____ if the trauma is severe
And about _____ if the trauma is ______
15-20 seconds
1-2 minutes if minor
Clotting factors include _____ ions, ______, ______ and ______
- Ca++ ions
- plasma proteins
- inactive enzymes
- chemicals released by PLTs