Unit 2 Lecture 10 Flashcards
What are platelets called?
Thrombocytes
What are platelets?
fragments of megakaryocytes
How long can thrombocyte cell fragments circulate for before death?
5-9 days
What percent of platelets circulate in the body?
66%
Where does the remaining 33% of platelets reside in the body?
In the spleen
Define thrombosis
the formation of a clot
Define thrombus
A clot
Define embolus
A circulating clot
Define hemmorage
a severe uncontrolled bleeding
What term describes how thrombocytes are made?
Thrombocytopoiesis
What type of stem cell produces megakaryocytes?
Myeloid stem cells
How are thrombocytes made from megakaryocytes?
Thrombopoietin (TPO) lets thrombocyte fragments to fall off the megakaryocyte
What internal process is responsible for bleeding to stop?
Hemostasis
What 3 phases make up hemostasis?
- Vascular spasm
- Platelet plug formation
- Coagulation (blood clotting)
What does a vascular spasm do?
Immediately vasoconstricts (makes diameter smaller) in response to injury -> stops blood flow
Where do vascular spasms occur?
In vessels with smooth muscle walls
What is angiotensin II?
a vasoconstricting hormone that effects the renal sympathetic nerves
During plug formation, what do platelets normally NOT do?
do not stick to each other or the endothelial lining of blood vessels
What do platelets stick to in a damaged blood vessel?
Collagen fibers
What do platelets do when they are activated by collagen fibers in damaged blood vessels?
- liberate thromboxane A2, serotonin, and ADP
- release ADP
How does the damaged vessel make a “plug”
ADP makes platelets sticky and thromboxane A2 and serotonin causes cell contraction -> plug
What word means blood clotting
coagulation
Where do most of the clotting factors come from in the body?
Liver
During coagulation, what type of stimulations are present?
intrinstic and extrinsic stimulations
Which type of stimulation is slower during coagulation?
intrinsic
What must be completed in order for effective clotting to occur?
the common pathway
What happens during the common pathway?
Prothrombinase is activated and it converts prothrombin into thrombin
What are the 2 main functions of thrombin?
- converts fibrinogen to fibrin
2. Activates factor XIII, which stabilizes the fibrin network
What are some of the different clotting factors found in the liver?
Prothrombin, fibrinogen, factors V, VII, IX, and X
What is needed for the synthesis of clotting factors?
Vitamin K
What is the importance of vitamin K during coagulation?
W/out vitamin K leads to failure of blood clotting = wont stop bleeding
What are people called who lack factor VIII?
Hemophilacs
What can’t form without factor VIII?
prothrombinase
What is prothrombinase?
A clotting factor that turns prothrombin into thrombin with Ca2+
What must happen to an embolus before entering the blood stream?
it must dissolve
What word means the dissolution of a clot?
fibrinolysis
What digests the fibrin strands and breaks the clot?
plasmin
What makes plasmin?
tissue plasminogen activator, thrombin, and plasminogen
