CVS physiology

Question 1

what is the function of the CVS

Answer 1

to be a bulk flow system for O2, CO2, nutrients, metabolites, hormones + heat

also to be flexible (vary output, redirect blood, store blood)

Question 2

why is it important for vascular beds to be in parallel and not series

Answer 2

so that all tissues get oxygenated blood and so that you have a system capable of redirecting blood flow as needed

also different organs have different O2/blood flow demands

Question 3

what are capacitance vessels

Answer 3

vessels which hold a lot of volume - veins and venules

(veins/venules hold 2/3s of blood at. rest)

Question 4

describe the structure of the aorta

Answer 4

elastic artery with wide lumen

thick elastic wall to dampen pressure variations

Question 5

describe the structure of arteries

Answer 5

muscular arteries with wide lumen
strong/thick non-elastic wall
low resistance conduits

Question 6

describe the structure of arterioles

Answer 6

resistance vessels with narrow lumen
thick contractile wall to control resistance + flow

Question 7

describe the structure of capillaries

Answer 7

exchange vessels with narrow lumen
thin wall

Question 8

explain the action potential in non-pacemaker cells

Answer 8

• at RMP (-90mV) cell has high resting K permeability
• increased Na permeability causes initial depolarisation
• Na permeability quickly decreases following depolarisation
• in the plateau following depolarisation permeability to decreases + increases for Ca (L-type channels)
• during repolarisation there is a decrease in Ca permeability and increase in K permeability