Lecture 9

Question 1

what are the four ways that active muscle gets more oxygen during exercise

Answer 1

1. local vessels dilate due to metabolites
2. cardiac output increases
3. blood flow redistributed to active muscle
4. increased oxygen extracted from each unit of blood

Question 2

net flow of blood to tissue is a balance of ……. control (2)

Answer 2

intrinsic / local control

extrinsic / global control

Question 3

what is extrinsic control mainly controlled by

Answer 3

sympathetic nervous system (via NAd and Ad)

Question 4

what organs receive more blood flow during exercise

Answer 4

heart and muscle

also skin

Question 5

what are myogenic mechanisms that provide local control of arteriolar tone (also where is this important)

Answer 5

• constrict against pressure (especially renal and cerebral arterioles) - these areas can not be exposed to high pressure

Question 6

what are the temperature mechanisms that provide local control of arteriolar tone

Answer 6

dilate with heat, constrict with cold

Question 7

what are the metabolic mechanisms that provide local control of arteriolar tone and why is this important

Answer 7

dilate with increased CO2, H+, K+, adenosine

dilate with decreased pO2

will cause local dilation of arterioles so there can be exchange between the local tissue

Question 8

what are the key humoral mechanisms that provide local control of arteriolar tone and what is this in response to

Answer 8

nitric oxide : in response to hypoxia and shear stress
- produced by epithelial cells in tissue

histamine : dilate during inflammatory reaction,

Question 9

how do the mechanisms such as myogenic, temperature, metabolic and humoral operate when controlling arteriolar tone

Answer 9

by negative feedback

Question 10

what happens when you double the radius in terms of blood flow

Answer 10

when you double the radius you get 16 times the blood flow

Question 11

what is the purpose of extrinsic control of arteriolar tone

Answer 11

1. ensure maintenance of MAP
2. ensure adequate perfusion of active tissues, especially during exercise

Question 12

what is the neural mechanism of extrinsic control of arteriolar tone

Answer 12

neural : sympathetic nervous system, releasing NAd in most arterioles

Question 13

what is the endocrine mechanism of extrinsic control of arteriolar tone and what do they do

Answer 13

ADH and ANG-II cause constriction

ADH will prevent you from producing as much urine, so will keep your fluid levels up

Question 14

what is the equation of blood pressure

Answer 14

blood pressure = cardiac output x total peripheral resistance

Question 15

what does systolic blood pressure estimate

Answer 15

• the work of the heart
• strain against arterial walls
• appropriate cardiovascular function

Question 16

what does diastolic blood pressure estimate

Answer 16

the total peripheral resistance

Question 17

what is mean arterial pressure equal to

Answer 17

2/3 DBP + 1/3 SBP

Question 18

what is the rate pressure product equal to

Answer 18

rate pressure product = systolic blood pressure + heart rate

Question 19

what does the rate pressure product tell us

Answer 19

the heart oxygen requirements

Question 20

compare RPP during exercise and rest

Answer 20

RPP ~6000 at rest to ~40,000 during exercise

Question 21

does blood pressure and heart rate increase more with arm or leg exercise and why

Answer 21

arm = due to cardiac output distribution

Question 22

what happens to blood pressure, cardiac output and total peripheral resistance during resistance exercise

Answer 22

blood pressure will increase because there is an increase in cardiac output but total peripheral resistance stays relatively the same

Question 23

short term control of blood pressure at rest is detected by what and causes what

Answer 23

detected by aortic and carotid baroreceptors

causes SNS ans PNS mediated responses

Question 24

long term control of blood pressure at rest is detected by what and causes what

Answer 24

detected by cardiopulmonary baroreceptors

causes mainly endocrine and renal responses

Question 25

3 forms of cardiovascular control during exercise

Answer 25

1. feedforward central command (dominates early)
2. Ergoreceptors important (muscle mechanoreceptors and chemoreceptors)
3. baroreceptors (-ve feedback)