Vascular System Flashcards
What 3 things is resistance determined by in blood vessels?
Length of vessel. radius of vessel and viscosity of fluid.
What factors determine the viscosity of blood? What does a high viscosity usually represent?
Number of red blood cells and amount of protein in blood.
High viscosity suggests a high haematocrit.
What are the effects of angiotensin II
Potent vasoconstrictor
What is shock?
Too low blood pressure
What are the 4 types of shock?
Hypovolaemic - loss of blood volume
Septic - infection leading to dilation of vessels
Anaphalactic - toxic amounts of histamine released causing leakage of blood into surrounding tissue
Cardiogenic - Pumping failure of heart
What is a poikilotherm?
An animal with a body temperature across a wide range (not necessarily an ectotherm!!)
What is convection?
Heat movement through a fluid (incl. air and water), e.g. blowing your tea!
Define hypoxia
Deficiency of O2 reaching tissues.
Why does altitude cause right sided hypertrophy/heart failure?
Because pulmonary vasoconstriction occurs (as a compensatory mechanism - would make sense if hypoxia were caused by reasons other than O2 intake!), increasing pressure in pulmonary circulation, so RHS has to pump harder.
What effect does Nitric Oxide (NO) have on blood vessels? What produces NO?
Very potent vasodilator produced by endothelial cells.
What is angiogenesis and what does it occur in response to?
Formation of new capillaries from pre-existing blood vessels. Occurs in response to hypoxia.
What is vascular ring anomaly?
A persistent right aortic arch, or a fibrous version of it, constricts the oesophagus.
