Circulation 1 Flashcards
What is the structure of blood vessels (arteries in particular) starting from the lumen and moving outwards?
lumen endothelium (several endothelial cells lining the arteries) basal lamina (connective tissue) smooth muscle interstitial collagen
What makes up blood?
Plasma
White blood cells
Red blood cells
Platelets
To what are platelets most commonly not exposed?
Interstitial collagen
What makes up plasma?
serum
Clotting factors
What is serum?
Serum is plasma without clotting factors (water and plasma proteins mainly albumin)
What are examples of clotting factors?
Fibrinogen
Prothrombin
What kind of system is the clotting cascade?
Amplification system
What is the process that follows initial damage?
The plasma becomes exposed to interstitial collagen fibres and the tissue factors in the smooth muscle get exposed to collagen
How do clotting factors get activated?
Through exposure of plasma and tissue factors from smooth muscles get exposed to the interstitial collagen where the tissue factors bind to the clotting factors and activate them.
How is clotting cascade initiated?
The Tissue Factors bind a particular clotting factor and initiate the clotting cascade
What component of clotting factors allows them to get sequentially activated?
The fact that they contain serine proteases that cleave off serine amino acids from the next clotting factors causing the serine amino acids to become activated.
What happens after the clotting factors have been activated?
Prothrombin is converted into thrombin and then fibrinogen is converted into fibrin
What marks the end of the clotting cascade?
The formation of fibrin insoluble aggregate strands
What kinds of cells do platelets form?
Megakaryocytes
What are megakaryocytes and how are they formed?
Large cells that have many nuclei that form by undergoing a lot of nuclear division but not cellular division
Where are platelets formed?
Bone marrow
What do platelets do when there is trauma?
They get exposed to interstitial collagen and they produce coagulation
What is thrombus composed of?
Fibrin mesh and platelets
What colour is pure thrombus?
Pale cream colour?
Where does a thrombus form and why?
In a flowing blood
Platelets have factors VII which allow platelets to adhere to interstitial collagen
How does blood clotting form?
Blood flows out of the blood vessel and it becomes stagnant and causes blood clot due to presence of red blood cells into fibrin strands
What is homeostasis referred to in the case of trauma?
Stopping bleeding
How is the clotting system activated?
By collagen and stagnant blood
What measures are taken to reduce bleeding if the blood clotting mechanism and the thrombus formation do not work?
Vasoconstriction takes place
