Physiology wk6

Question 1

what is the role of each blood vessel

Answer 1

Arteries – blood delivery
Small arteries/arterioles – flow regulation
Capillaries – fluid/nutrient exchange
Venules – collection
Veins – return

Question 2

what vessels are part of macrocirculation

Answer 2

• Conduit arteries
• Feed arteries

Question 3

what vessels are part of microcirulation

Answer 3

• Resistance arteries
• resistance arterioles
• terminal arterioles
• capillaries

Question 4

what influences help vasodilation

Answer 4

• neural
• hormonal – epinephrine/norepinephrine and AMP
• myogenic – lowers flow going to brain to reduce pressure going to the brain

Question 5

what is hyperaemia

Answer 5

blood flow increases to the metabolic activity of a tissue/organ

Question 6

what is hyperaemia stimulated by

Answer 6

• tissue hypoxia = not enough o2 delivery
• co2 increase
• pH decrease
• lactate production
• products of ATP
• osmolality
• potassium levels

Question 7

what do prostaglandis do

Answer 7

these increase the amount of swelling at damaged tissues

Question 8

what percentage of blood flow goes to muscles at rest and during exercise

Answer 8

20 at rest, rises to 80-85 during exercise

Question 9

what causes such a massive increase in blood flow

Answer 9

redistribution from inactive muscles and reduced blood flow to inactive organs

Question 10

what is autoregulation

Answer 10

• blood flow to meet metabolic demands of tissue
• Magnitude of vasodilation is proportional to size of recruited muscle mass
• Due to local changes (increased NO, prostaglandins, ATP and adenosine

Question 11

what is vascular shunting

Answer 11

blood splits off when traveling to the liver, this shunts blood to the hepatic artery to deal with products to be treated in the liver

Question 12

how does blood flow decrease

Answer 12

through sympathetic vasoconstriction and circulating catecholamines, o2 extraction increases to compensate (GLUT1 transporters sent out)

Question 13

what happens after splanchnic blood flow is constricted

Answer 13

venous return is increased

Question 14

what does the portal vein do

Answer 14

takes blood back to the heart through the liver, people with spine damage will have higher volumes in their portal vein as they cant shunt blood away efficiently

Question 15

what are the ways of sympathetic neural control of skin blood vessels

Answer 15

1. Adrenergic vasoconstrictor (non hairy skin) – noradrenalin neurotransmitter
2. Cholinergic vasodilator (hairy skin) – acetylcholine neurotransmitter

Question 16

why does vasodilation occur at higher thresholds during exercise than rest

Answer 16

• During exercise blood flow is shifted from core to surface to help cool
• Muscle pump cant assist in aiding venous return
• Filling of the heart is reduced and vasoconstriction must occur to maintain BP

Question 17

what happens to renal blood flow when hr increases

Answer 17

it will decrease alongside the digestive system

Question 18

how much of total cardiac output goes to the brain

Answer 18

20%

Question 19

why is habitual exercise good for the brain

Answer 19

maintains its size and usefulness

Question 20

what are the measures of brain blood flow

Answer 20

Brain perfusion imaging technique - MRI
Transcranial doppler – measures blood velocity as an index of flow
Near-infrared spectroscopy (NIRS) – measures balance of oxygen supply and demand at capillary level in cerebral cortex

Question 21

what happens to brain blood flow during exercise

Answer 21

is directly proportional to co2 levels, rises and falls at the same time/rate

Question 22

what can causae fainting

Answer 22

major increase or decrease in blood flow/pressure

Question 23

what happens to Brain blood flow during different bouts of exercise

Answer 23

with higher intensities there is more bbf

Question 24

what are the two endothelial derived relaxing factors (EDRF’s)

Answer 24

nitric oxide
prostoglandins

Question 25

what factors regulate blood flow in different vessel types

Answer 25

conduit arteries = sympathetic vasoconstriction
feed arteries = EDRF’s
arterioles = metabolic vasodilation

Question 26

what is splanchnic circulation

Answer 26

circulation to liver, GI tract, pancreas and spleen

Question 27

how is skin (cutaneous) circulation neurally controlled

Answer 27

adrenergic vasoconstrictor - for non hairy parts (palms and lips)
cholinergic vasodilator - for hairy parts (arms and legs)

Question 28

how is blood pressure/venous return maintained when it’s too hot

Answer 28

to compensate for blood flow to skin, vasoconstriction occurs to maintain bp

Question 29

what happens to blood flow during exercise regarding constriction/dilation

Answer 29

vasoconstriction at onset of exercise (to increase bp and bf), then dilation during to maintain core heat, then more constriction to maintain venous return

Question 30

what factors regulate brain blood flow

Answer 30

blood pressure
cardiac output
metabolism
sympathetic nervous activity
parasympathetic nervous activity
cerebal autoregulation

Question 31

when does brain blood flow stop increasing

Answer 31

increases from resting values till up to 65% vo2 max and then lowers after this amount (like inverted u)

Question 32

what is the brains most dominant regulator

Answer 32

pco2

Question 33

what regulates local blood flow during exercise

Answer 33

vasodilation (lowers resistance) increases bf to meet metabolic demands (cholinergenic)
due to increase: no, prostaglandin, atp and adenosine

vasoconstriction to reduce bf and increase resistance (adrenergic)

Question 34

how much blood to skin at rest/exercise

Answer 34

100-300ml at rest
7-8L during

Question 35

how much blood flow to renal

Answer 35

1200ml rest to 360 during exercise

Question 36

how much blood flow to sphlanic

Answer 36

1500ml during rest, 350 during exercise

Question 37

what was the dallas bed rest study

Answer 37

after 20 days bed rest, when returned to training stroke volume and cardiac output where higher, heart rate was lower at same intensities