Mid: Thermoregulation Additional Slides

Question 1

what percent of blood flow is going skeletal muscle at rest? and what percent during maximal exercise?

Answer 1

• 15-20% of cardiac output

- 80-85% of cardiac output

Question 2

redistribution of blood during exercise depends on what?

Answer 2

Intensity

Question 3

oxygen delivery changes during exercise due to? (2)

Answer 3

1. an increased cardiac output

2. a redistribution of blood flow (use of autoregulation)

Question 4

Cardiac out put increases as a linear function with VO2…. what maintains this linear relationship?

Answer 4

idk lets look it up right now

Question 5

during exercise what happens to blood flow to visceral organs and inactive tissues?
what happens at active skeletal muscle?

Answer 5

• vasoconstriction

- vasodilation

Question 6

what causes vasodilation during exercise: (autoregulation) (70

Answer 6

1. increased temp
2. elevated CO2
3. Lowered pH
4. Adenosine
5. Nitric oxide
6. ions (mg2 and K+)
7. Ach

Question 7

what cause vasoconstriction during exercise?

Answer 7

norepinephrine

epinephrine

Question 8

capillary recruitment increases from 5-10% to what percent during exercise?

Answer 8

almost full

Question 9

what do norepi and epi do during exercise?

Answer 9

increase calcium available to myocardial cell= increased cross bridge activation and increased force production

Question 10

Pre capillary sphincters can be relaxed to increase local blood flow. what factors control this relaxation?

Answer 10

idk lets look!

Question 11

greater capillary perfusion at the lungs =

Answer 11

increases/decreased local blood flow?
increase/decrease speed of blood flow?

hate her

Question 12

1 of every ? capillaries in muscle is open at rest

Answer 12

30-40

Question 13

capillary perfusion during exercise does what? (3)

Answer 13

1. increases blood flow to muscle
2. reduces speed of blood flow
3. increases surface area for gas exchange at working tissues

Question 14

what does nitric oxide do to promote vasodilation

Answer 14

• promotes smooth muscle relaxation which results in vasodilation and increased blood flow

Question 15

where is nitric oxide produced?

Answer 15

endothelium of the arterioles

Question 16

what is the 4 components of the recipe for success to ensure adequate blood flow to muscles

Answer 16

1. provide adequate cardiac output
2. distribute arterial blood tot he muscles demanding oxygen
3. divert some of the blood flow away from less active areas
4. maintain blood pressure

Question 17

what does flow equal?

and what does blood pressure maintained by?

Answer 17

Flow= change in pressure/resistance

maintain Pressure=increase flow and decrease resistance

Question 18

does systolic or diastolic of both BP increase during exercise?

Answer 18

just systolic, diastolic remains relatively constant

Question 19

why does MAP not increase as much as cardiac output during exercise?

Answer 19

in order for the heart to eject blood, the pressure generated by the left ventricle must exceed the pressure in the aorta (MAP)

• an increase in aortic pressure = a decrease in stroke volume
• -> minimized during exercise by arteriole dilation

Question 20

what one variable decreases during exercise

Answer 20

total peripheral resistance

Question 21

why is mean arterial pressure higher in arms compared to legs only in exercise?
(we supposed to think about ALL the variables influences HR and MAP)

Answer 21

greater sympathetic outflow to the heart during arm exercises compared to legs which results in increase in BP

• there is vasoconstriction in all the inactive muscle groups
• -> in larger muscle groups (legs) the more resistance arterioles that are dialated (lower peripheral resistance = lower pressure)

Question 22

cardiac output=

Answer 22

HR x SV

Question 23

fick equation: VO2 =

Answer 23

Q x a-vO2 diff

Question 24

VO2 max =

Answer 24

max Q x max a-vO2

Question 25

what enhances consumption of O2 at the tissues? (increased a-vO2 diff)

Answer 25

idk either ugh

Question 26

during exercise, arterial O2 content (inc/dec) and mixed venous O2 content (inc/dec)

Answer 26

• increases

- decreases

Question 27

what is the difference in untrained vs trained ppl’s mitochondrial # and ADP concentration

Answer 27

untrained: high [ADP] needed to stimulate mito
trained: more mito to share ATP production means stimulation at lower [ADP] which provides greater O2 uptake

Question 28

what are the causes of the differences in VO2 among trained and untrained subjects

Answer 28

look into this

Question 29

what does the oxyhemoglobin dissociation curve represent?

Answer 29

• the manner at which oxygen can be “unloaded” at the working tissues

Question 30

describe the 3 explanations for the lactate threshold

Answer 30

1. epi increases rate and accumulation of NADH in that it exceeds its shuttle mechanism, so results in pyruvate accepting the unshuttled H+ and turning into lactate
2. increased work= increase recruitment of fast fibers whose LDH has a higher affinity for pyruvate to form lactate (slow fibers contain LDH for changing lactate to pyruvate)
3. increase of lactate entry into the blood and decrease rate of removal