Introduction to Haemostasis Flashcards
What is haemostasis?
The process that maintains the flowing blood in a fluid state and confined to the circulatory system
What is vasoconstriction?
Peptides and hormones cause contraction of smooth muscle cells in the vessel wall.
What is the purpose of vasoconstriction
After injury, makes hole that blood is flowing through smaller to decrease the amount of blood we lose
What hormones are produced by activated platelets?
Thromboxane and serotonin
What is angiotensin secreted by?
Liver
What is vasopressin/ADH secreted by?
Posterior pituitary gland
What is purpose of microtubules inside platelets?
Increase SA:Vol
What are the 2 types of granules inside platelets?
Alpha and dense
What are platelets produced by?
Megakaryocytes in the bone marrow
What is the main initial trigger for platelet activation?
Collagen
Why is serotonin released by activated platelets?
It is thus active wherever platelets bind in damaged tissue, as a vasoconstrictor to stop bleeding, and also as a fibrocyte mitotic (growth factor), to aid healing.
How is serotonin stored in blood?
In blood, serotonin is collected from plasma by platelets, which store it in dense granules
What do alpha granules in platelets contain?
Platelet Derived Growth Factor, platelet factor 4, Factors V & XIII and fibrinogen.
What do dense granules in platelets contain?
Dense bodies contain serotonin, nucleotides (ADP and ATP) and calcium.
