Exam #2 Chapter 8

Question 1

T/F Reliable estimates of a true RHR can be made immediately before exercise

Answer 1

False

Question 2

Explain the physiological factors that impact the anticipatory response of HR

Answer 2

Anticipatory response: HR above RHR just before the start of the exercise Vagal tone, Norepinephrine, epinephrine.

Question 3

T/F The more intense the exercise, the longer it takes to reach steady-state HR

Answer 3

True, When intensity goes up, HR will go with it. They must correlate together

Question 4

T/F Those with better cardiorespiratory endurance have a higher steady-state HR at each exercise intensity compared to those who are less fit.

Answer 4

True

Question 5

T/F SV increases up to 100% VO2max

Answer 5

False, SV increases up to 40-60%

Question 6

Explain why the increase in SV in the supine position is not as significant as the increase in the upright position

Answer 6

During supine (recumbent) - SV increases but usually by only about 20-40%, Not nearly as much as in an upright position, Supine EDV > standing EDV, In standing position, venous return is lower compared to in the supine venous return it will be higher (body is not fighting against gravity)

Question 7

There are several factors that increase SV. Explain these in detail, including how each variable impacts one another.

Answer 7

1) Higher volume means greater stretch of the ventricles (water balloon example) Increased force of contraction also (rubber band ex.) Blood being ejected from the LV will increase which increases SV (back to water balloon example)

2) Increase catecholamine release –> increase the force of ventricular contraction –> Increase stroke volume (no effect of EDV) –> Increase of ejection fraction (this is % of EDV ejected)

3) Decreased afterload (i.e. aortic resistance)
Resistance is provided by the radius of the vessels. Aorta will send blood out to other arteries. Exercise/vasodilation will decrease aortic resistance because the aorta is not working against high resistance

Question 8

T/F Cardiac output increases up to 100% VO2max HRxSV

Answer 8

True

Question 9

Explain sympathetic vasoconstriction and how it is offset during exercise. Your answer should include metabolic and endothelial mechanisms of blood flow redistribution.

Answer 9

Sympathetic vasoconstriction is shunting blood away from less-active regions, Splanchnic circulation (liver, pancreas, GI), Kidneys

Question 10

Explain, in detail, cardiovascular drift

Answer 10

Cardiovascular drift is when core temp is high vasodilation will occur to the peripherals or skin which will cause a lower venous return and a lower stroke volume. Also sweating will occur which will lower plasma volume and will result in a lower stroke volume.

1. In heat, blood to the periphery. Essentially will decrease venous return to heart (not much blood returning to the heart)
   Lower venous return will decrease overall SV in this instance
2. Lot of sweating in heat - plasma concentration/volume will decrease and will decrease SV

Need to maintain CO (HR x SV)
CV drift is when HR is drifting up in order to maintain CO (explains why we have higher HR in the heat compared to a neutral or cold environment

Question 11

Explain and draw AVO2 difference. In your answer, explain how AVO2 differences change from rest to exercise and why this change occurs.

Answer 11

REST:
When looking at the AVO2 in rest, you are going to start with 100 mL in the arteriole, which then you are going to lose 20 mL in the capillaries which will lead to 80 mL in the venules.

EXERCISE
When looking at the AVO2 in exercise, you are going to start with 100 mL in the arteriole, which then you are going to lose 60 mL in the capillaries which will lead to 40 mL in the venules.

MAIN CONCEPT IS THAT DURING EXERCISE YOU ARE GOING TO USE MORE ML (IN BLOOD) IN THE CAPILLARIES COMPARED TO REST

Question 12

Why does plasma volume decrease during exercise?

Answer 12

Plasma volume decreases during exercise because when sweat rate increases, fluid leaves the blood and allows for better oxygen movement through the blood in hemoglobin.

Question 13

What is hematocrit?

Answer 13

The portion or percentage of red blood cells in the blood

Question 14

Explain what hemoconcentration is and its’ effects

Answer 14

Hemoconcentration is the concentration of red blood cells in a volume of plasma, this causes a reduction in the circulation of blood through the body.

Question 15

Explain why the valsalva maneuver may be dangerous in older adults or those with cardiac issues

Answer 15

The valsalva maneuver may be dangerous in older adults or those with a CVD condition because the pressure it can apply on the vena cavas can be potentially dangerous and can be fatal