Cardiovasc system Flashcards
Arteries
-Carry blood away from heart under high pressure
-Transport oxygenated blood (except pulmonary)
-No valves
-Reddish colour
-Thicker walls than veins
Veins
-Carry blood towards heart under low pressure
-Transport deoxygenated blood (except pulmonary)
-May contain valves to prevent backflow
-Blueish colour
-Thinner walls than arteries
Capillaries
-Between arterioles and venules
-Only 1 layer (tunica intima)
Vein and artery walls
Tunica intima, Tunica media and tunica adventitia are the 3 layers
Blood composition
Plasma - contains nutrients/waste/antibodies
Plasma proteins - Albumin maintains osmotic concentration and fibrinogen and prothrombin form blood clots.
Blood functions
- Transport gases to/from body and lungs
- Transport nutrients
- Transport waste products to liver/kidney
- Regulates body fluid volume
- Defends against infection
- Regulates body temperature by conducting heat
How are erythrocytes formed
Formed by erythropoiesis in bone marrow, which takes 4-7 days. Production is controlled by Erythropoietin.
Erythrocyte function
Transports oxygen and some CO2
Leucocytes function
-Defend the body against infections
-Have nuclei
Granulocytes types (leucocytes)
-Basophils secrete histamine
-Neutrophils phagocytose bacteria
-Eosinophils are involved in allergic responses
Agranulocyte types (leucocytes)
-Lymphocytes produce antibodies (B)
-Monocytes transform into macrophages
How are thrombocytes/platelets formed
-Formed from megakaryocytes in bone marrow
Thrombocytes function
-Blood clotting
How does blood clotting work?
- Platelets stick to damaged blood vessel and release THROMBOPLASTIN.
- This converts PROTHROMBIN TO THROMBIN
- THROMBIN converts FIBRINOGEN to FIBRIN to make a clot.
-Clotting time is increased by lack of vit K and decreased by raised temperatures.
What is a thrombus
A blood clot blocking a vein/artery.