1. structure + function of CVS

Question 1

factors affecting area available for diffusion

Answer 1

1. capillary density - more capillaries, higher density

2. metabolic active tissues - more capillaries for exchange to keep up demands

Question 2

factors affecting diffusion ‘resistance’

Answer 2

1. how wide the pore is - nature of barrier
2. how large the molecules are - size
3. diffusion path length

Question 3

factors affecting diffusion gradient

Answer 3

greater difference in concentration of molecules

slow flow rate, small conc. gradient, less O2 diffusion

Question 4

critical importance of adequate blood flow for maintenance of capillary exchange

Answer 4

low blood flow = low capillary concentration = low diffusion rate = low rate O2 into cells

Question 5

normal cardiac output for adult male at rest

brain, heart, kidneys, any changes

Answer 5

whole CVS 5L/min-25L/min (exercise)
brain constant high flow: 0.75L/min
heart: 0.3L/min-1.2L/min
kidneys: 1.2L/min
gut after meal - bloodflow increase
skeletal muscle - increase with exercise

Question 6

Perfusion rate?

Answer 6

Rate of blood flow

Question 7

How come blood flow changes in some organs and remains constant in others?

Answer 7

blood flow to body organs increase as conditions become more extreme
e.g. sleeping VS strenuous exercise (greater blood flow to fulfil the oxygen demand in highly respiring tissues)

Question 8

Why is ability to change blood flow to skin important?

Answer 8

vasodilation to loose heat

vasoconstriction to maintain body temperature

Question 9

describe function of heart in circulation

Answer 9

pump - 2 pumps in series
Left: pump around systemic circulation (tissues + organs)
Right: pump around pulmonary circulation (lungs) deoxy –> oxygenated

Question 10

what is the function of blood?

Answer 10

transporter of oxygen

Question 11

function of vessels + blood in circulation?

Answer 11

distribution system throughout the circulation

Question 12

Function of veins

Answer 12

Capacitance - ability to store blood

Question 13

function of arterioles

Answer 13

resistance vessels
needs to be added to the system - reduce blood flow from parts of body to direct blood flow to more difficult parts (going against gravity) e.g. direct blood flow away from legs to brain

Question 14

Distribution of blood volume over major parts of the circulation

Answer 14

at rest: 5L
veins: 67% (3.9L)
Heart + lungs: 17%
arteries + arterioles: 11%
capillaries: 5%

Question 15

advantage of veins as capacitance

Answer 15

veins have thin walls - easily expand / collapse - variable reservoir for blood

Question 16

Why does body require a capacitance?

Answer 16

total outflow of blood has to be flexible - change to body’s needs
requires temp store of blood
temp store has to enter heart to give increased output

Question 17

Factors that influence the exchange of substances between the blood in capillaries + surrounding tissues

Answer 17

1. area for diffusion
2. diffusion ‘resistance’
3. concentration gradient