November 22, 2023

Question 1

Questions at beggining of lecture:

1. How old is a person with a maximum HR of 145? (75 years)
2. If Q=22 L/min and HR is 120 bpm, what is the SV? (183 ml/beat)

Question 2

HR Response to Exercise After Heart Transplantations

Answer 2

Heart beats at a higher HR at rest (aka intrinsic HR) (predominantly due to parasympathetic suppression; s)

HR won’t go up as much during exercise as it would in a heart with normal neural control

Question 3

what is the formula for Q (cardiac output)

Answer 3

Q (cardiac output) = HR x SV

Question 4

Effect of Prolonged Exercise in the Heat in regards to SV

Answer 4

Prolonged exercise in the heat causes SV to go down

This causes HR to slowly increase to compensate for decrease in SV (cardiac drift)

SV is affected first (loses 10-15%); increase in HR by the same proportion

page 143

Question 5

Effect of Prolonged Exercise in the Heat in regards to Sweat rate and respiratory water loss

Answer 5

Sweat rate and respiratory water loss is increased;

this causes plasma volume and blood volume to decrease

causes cardiac output to potentially go down

page 143

Question 6

Effect of Prolonged Exercise in the Heat in regards to MAP

Answer 6

Exercise in heat also increases MAP

which increases capillary pressure,

which causes an increase of movement to the interstitial fluid;

this also reduces plasma and blood volume

page 143

Question 7

what are the two primary causes of slow decline in SV as a result of Prolonged Exercise in the Heat

Answer 7

1. increases MAP
2. Sweat rate and respiratory water loss is increased

causes the slow decline in SV (less blood is flowing back to the heart for every beat)

page 143

Question 8

what reduces the drop in plasma volume, and attenuates cardiac drift

Answer 8

Fluid replacement

reduces the drop in plasma volume, and attenuates cardiac drift

page 143

Question 9

Effect of Endurance Training on HR

Answer 9

Lower resting HR in trained person compared to untrained (at any workload up until max; workload that was max before now becomes max; can’t change max HR though)

Bradycardia (lower HR): evident at rest and submaximal exercise mainly due to an increase in parasympathetic tone

Question 10

Benefits of Endurance Training on HR

Answer 10

Better coronary BF and more time for LV filling

Lower energy demand for the heart = less O2 required

Question 11

Is Q(cardiac output) the same in trained and untrained subjects?

Answer 11

Even though there is a lower HR,

Q is the same in trained and untrained subjects during submaximal exercise because the SV increases to compensate

Better supply:demand ratio

Question 12

what is the formula for SV

Answer 12

SV = EDV (amount in heart when filled) - ESV (what is left after heart ejects)

Question 13

SV is higher in trained or untrained individuals

Answer 13

SV is higher in trained individuals (ejects more)

Question 14

SV plateaus at about what percentage of VO2 max

Answer 14

SV plateaus at about 40% VO2 max

for both trained and untrained

Question 15

why is SV higher in trained individuals

Answer 15

As training progresses, bradycardia occurs as an early adaptation (increase in parasympathetic drive)

Lower HR leads to:
* ↑ diastolic time →
* ↑ ventricular filling →
* stretches ventricular wall →
* eccentric hypertrophy (adaptation over time/longer cells) →
* ↑ ventricular volume →
* ↑ EDV

Question 16

As training progresses, bradycardia occurs as an early adaptation. What occurs as a result of the adaptation

Answer 16

After adaptation, you get an increase in EDV and more blood leaving the heart per beat at the same ejection fraction of 50%

because ventricles holds a greater volume than before thus at the same ejection of 50% we have a higher SV

see page 145 image on bottom for clarification

Question 17

Effect of Endurance Training on myofibrils

Answer 17

Training also increases the sensitivity of the myofibrils to calcium → greater force at a given cytosolic calcium → improved contractility

Question 18

Ejection fraction =

Answer 18

SV/EDV x 100

or

(EDV-ESV)/EDV x 100

question at bottom of page 146

Question 19

Effect of Exercise Intensity on SV

Answer 19

Increase in venous return

Question 20

what is the primary purpose of One way valves in veins

Answer 20

One way valves in veins prevent backflow of blood (more return to the heart).

Question 21

function of the venous valves and the “muscle pump” during contractions

Answer 21

Increase in sympathetic drive; some veins have smooth muscle which contracts (venoconstriction) via NE acting on a1 adrenergic receptors

Muscle contraction squeezes the veins and increases venous return to the heart

Question 22

what are Varicose veins and how do they occur

Answer 22

Varicose veins: due to overloaded valves

heredity, sex (females more than males)

due to breakdown in valves (more pressure);

important for people to move so blood does not pool and breakdown valves

Question 23

how is Exercise is helpful for people with varicose veins

Answer 23

Exercise is helpful for people with varicose veins as it increases muscle tone and prevents blood pooling