November 29, 2023

Question 1

Questions at beginning of lecture:

1. Explain to yourself how digitalis works
2. Why is training-induced bradycardia such an important adaptation?

Question 2

Smooth muscle tone:

Answer 2

how much vasoconstriction or vasodilation

Question 3

how does Smooth muscle tone work

Answer 3

NE binds to alpha1 adrenergic receptors and causes contraction of smooth muscle and narrowing of vessel

Question 4

Sympathetic drive =

Answer 4

vasoconstriction (increased vascular tone)

Modest vasoconstriction is usually occurring in our bodies at any given time

Question 5

Metabolites produced by exercising muscle …….

Answer 5

reduces vascular smooth muscle contraction/tone (opens vessels to improve flow)

Question 6

what are the two metabolites produced by exercising muscle

Answer 6

Adenosine

Potassium

Question 7

How does Adenosine (metabolite) reduce vascular tone

Answer 7

AMP becomes adenosine when it loses a phosphate (ATP without the phosphate)

This means that adenosine can escape the cell since it is phosphate free

This acts as a metabolite that inhibits the release of NE from sympathetic neurons; no NE means reduction in vascular tone and will widen

Question 8

How does Potassium (metabolite) reduce vascular tone

Answer 8

inhibits NE release from sympathetic neurons

Question 9

Central command consists of:

Answer 9

Recruiting motor units so you can exercise

• Sympathetic drive →
• NE release →
• binds to a1 adrenergic receptors on vascular smooth muscle →
• vasoconstriction everywhere

But, in exercising muscle:

• metabolites(ex: K and adenosine) →
• inhibit NE release locally →
• vasodilation →
• increase in blood flow

Question 10

Vasoconstriction is happening everywhere except where you are exercising

Question 11

Vasoconstriction and Vasodilation during exercise lead to

Answer 11

a redistribution of blood flow

Question 12

Mom said: “wait 2 hours after you eat before going swimming!” Why?

Answer 12

competition between redistribution of blood flow

between digestive muscles and skeletal muscles

causes cramps

Question 13

does brain blood flow increase during exercise?

Answer 13

yes

Question 14

does skin blood flow increase during exercise

Answer 14

yes

Blood flow increases for heat dissipation or is reduced for heat conservation (depends on environment temp)

Question 15

Factors that increase blood flow to skeletal muscle as a result of skeletal muscle activity

Answer 15

Metabolic vasodilation

Muscle pump

Increase in sympatho-adrenal system

Deeper Breathing

Question 16

how does skeletal muscle activity → Metabolic vasodilation → increase BF in skeletal muscle

Answer 16

skeletal muscle activity →
Metabolic Vasodialtion →
↓ total peripheral resistance →
↑ SV →
↑ Q →
↑ BF in skeletal muscle

also because:
easier for heart to eject blood

Question 17

how does skeletal muscle activity → Muscle pump → increase BF in skeletal muscle

Answer 17

skeletal muscle activity →
Muscle pump →
improved venous return →
↑ SV →
↑ CO →
↑ BF in skeletal muscle

Question 18

Increase in sympatho-adrenal system → increase BF in skeletal muscle

Answer 18

Increase in sympatho-adrenal system →
↑ cardiac rate and SV →
↑ CO →
↑ BF in skeletal muscle

also:
increases sympathetic vasoconstriction in viscera
redistributes blood flow to places where it’s needed

Question 19

How does Deeper breathing → increase BF in skeletal muscle

Answer 19

Deeper breathing →
↓ intrathoracic pressure →
Improved VR
↑ SV →
↑ CO →
↑BF in skeletal muscle

Question 20

MAP =

Answer 20

(HR x SV) x TPR

Question 21

Metaboreceptors (IV afferents) respond to?

Answer 21

metabolites and help to increase
sympathetic drive to the heart and periphery

Question 22

Mechanoreceptors (III afferents) respond to

Answer 22

contractile activity leads to increase in
AP frequency which accelerates sympathetic outflow

Question 23

Mechanoreceptors (III afferents) and Metaboreceptors (IV afferents) are known as

Answer 23

“pressor reflex” and acts opposite to BRR

Question 24

what is Baroreceptor reflex

Answer 24

have protective mechanisms that prevent over increase in BP

Question 25

Factors that influence BP Response to Exercise

Answer 25

Amount of active vs. inactive muscle mass

Intensity and duration of contractile effort

The type of contraction; resistance vs. dynamic - determining blood vessel compression and blood distribution

valsalva maneuver and changes in intrathoracic pressure determining venous return to heart

Question 26

what do the factors that influence BP response to exercise determine:

Answer 26

extent of the pressor reflex
amount of sympathetic drive
degree of vasodilation (reduction of TPR)

Question 27

Valsalva maneuver

Answer 27

leads to increase in thoracic pressure