Neural signals originating from metabolic

 Neural signals originating from metabolic 

Of the factors that can influence stroke volume, which do you think contributes to the rise in stroke volume during exercise?

Increased afterload
Increased contractility
Increased heart rate
All of the above

 

·         increased Contractility

 

Based on the Krogh hydraulic model, which of the following would increase preload during exercise?

Vasodilation of skin blood vessels
Vasodilation of splanchnic blood vessels
Vasodilation of skeletal muscle blood vessels
None of the above

 

·         None of the above
**vasoconstriction to non-active muscles is what increases preload during exercise

 

If you are 20 years old, what is your estimated maximal heart rate?

180
200
220
240

 

·         200

**220-age=max HR

Which of the following variables are NOT included within the terms of the Fick equation?

Arterial O2 content
Mixed venous O2 content
Heart rate
Arterial pressure

 

·         Arterial pressure

*Fick EQ: Vo2 = HR SV *(a-v O2 diff)

 

 

During exercise, blood flow will decrease to which of the following tissues/organs?
Brain
Heart
Kidneys
None of the above

 

·         Kidneys

 

What are the three cardiovascular adjustments that must occur in response to exercise.

 

·         increase in sympathetic nervous system activity
2. increase in venous return (preload) in proportion to CO
3. redistribution of cardiac output

 

Which of the following factors contribute(s) to the rise in stroke volume during whole-body rhythmic exercise?

a. An increase in cardiac contractility that is caused by the increase in activity of cardiac sympathetic nerves
b. The Frank-Starling mechanism (vasoconstriction)
c. An increase in heart rate
d. Both a and b
e. All of the above

 

·         d. Both a and b

**not c because an increase in HR might initially raise SV, but will eventually cause a drop in bp which will ultimately decrease SV

 

Exercise hyperpnea refers to which of the following?

a. A linear rise in ventilation in proportion to the rise in blood lactate
b. A linear increase in ventilation that is proportional to the increase in metabolism
c. The overwhelming sensation of being "short of breath"
d. The rise in blood flow to active skeletal muscle

 

·         b. A linear increase in ventilation that is proportional to the increase in metabolism

 

       

 

During exercise, which of the following factors determine(s) how much O2 is unloaded from hemoglobin in the active skeletal muscle?

a. A shift in the oxygen-hemoglobin dissociation curve
b. A fall in tissue PO2
c. All of the above

 

·         c. All of the above

 

Which of the following correctly describes the relationship between values for venous O2 content from different regions in the body?

a. Exercising skeletal muscle > resting tissue > mixed venous
b. Exercising skeletal muscle < resting tissue < mixed venous
c. Exercising skeletal muscle > mixed venous > resting tissue
d. Exercising skeletal muscle < mixed venous < resting tissue

 

·         d. Exercising skeletal muscle < mixed venous < resting tissue

 

Compare and Contrast exercise hyperemia and functional sympatholysis

 

·         Exercise hyperemia is the increased blood flow due to dilation of blood vessels in an active muscle tissue during exercise. Functional Sympatholysis is the constriction of blood vessels not active during exercise as a result of increased sympathetic NS activity.
Similar:
-both aim to properly distribute blood during exercise
-both receive increased adenosine and ATP signals from skeletal muscle
Different:
-hyperemia causes vasodilation due to LOCAL vasodilators whereas functional sympatholysis causes vasoconstriction due to sympathetic NS activity
-blockage of one or more signals from skeletal muscle in exercise hyperemia is not likely to cause any issues whereas a blockage of signals from skeletal muscles in functional sympatholysis is likely to reduce responsiveness of adrenergic receptors

 

Which of the following statements are true regarding ventilation of the alveoli during exercise?

a) The ability to ventilate the alveoli does not generally limit exercise performance in healthy individuals
b) Training to improve the ability to ventilate the lungs improves performance in most people
c) Ventilation rises because PCO2 of the arterial blood is higher during exercise
d) Both a and c
e) None of the above

 

·         The ability to ventilate the alveoli does not generally limit exercise performance in healthy individuals

 

The ventilatory adjustments at the onset of exercise are activated by which of the following:

a) Neural signals, originating from higher brain centers, known as "central command"
b) Neural signals originating from metabolic imbalances in the active muscle
c) Central and/or peripheral chemoreceptors
d) The fall in arterial PO2

 

·         Neural signals, originating from higher brain centers, known as "central command"

 

Which of the following are characteristics of exercise-induced arterial hypoxemia?

a) Occurs in most individuals if they exercise hard enough
b) Results in a reduced arterial content of oxygen
c) Alveolar and arterial PO2 are in equilibrium

 

·         b) Results in a reduced arterial content of oxygen

 

Following endurance training, which of the following allows for an increase in O2 delivery to skeletal muscle during maximal exercise?

a) Increased capillarization of trained skeletal muscle which reduces the distance for O2 diffusion
b) Greater recruitment of existing capillaries in trained skeletal muscle which increases blood flow
c) Greater cardiac output which supports a greater muscle blood flow
d) Both a and c
e) All of the above

 

·         e) All of the above

 

Which of the following factors is associated with an improved stroke volume at rest and during exercise as a result of cardiorespiratory endurance training?

a) Increased blood volume
b) Decreased end-diastolic volume
c) Greater capillarization
d) Both a and c
e) All of the above

 

·         Increased blood volume

 

Which of the following observations suggest to you that the cardiovascular system is more limiting than the respiratory system during exercise?

a) The presence of a "respiratory steal" during exercise
b) Ventilatory capacity is greater than ventilatory demand
c) The absence of exercise-induced hypoxemia in most individuals
d) Both a and c
e) All of the above

 

·         e) All of the above

 

Thinking about gas exchange, explain the difference between the terms "Transit Time" and "Equilibration Time," identify their relationship to each other during rest and exercise in a normal healthy individual (i.e., which is longer, which is shorter), and indicate the significance of a reversal of this relationship.

 

·         transit time refers to the mean amount of time it takes for a RBC to enter and exit capillaries in the lungs (usually 0.8 sec)
2. equilibration time is the time taken for the O2 content to fall 90% from initial measurement to final measurement (usually 0.5 sec)
If these two phenomenon switched times, there would be a decrease in capillary O2 levels because the blood would be traveling too quickly for it to equilibrate.

 

At rest O2 uptake across the lungs can be described as which of the following:

 

·         perfusion limited, because the rate of blood flow determines the overall rate of O2 carried away from the lungs

 

Diffusion limitation is typically prevented in young healthy, untrained individuals by which of the following processes:

 

·         pulmonary capillary blood volume increases

 

Respiratory Steal Phenomenon

 

·         respiratory muscles steal ~15% of total oxygen consumed during heavy exercise

**this is because the majority of cardiac output is going to the active skeletal muscles

 

What is the cost of breathing more

 

·         -increased work of breathing will decrease blood flow to the legs
-decreased work of breathing will increase blood flow to the legs

 

What is the cost of breathing more?

 

·         breathing more creates an elastic recoil that the muscles have to work against

 

How does blood adapt to training?

 

·         -endurance training increases blood vloume
-blood volume increases due to an increase in plasma volume
-RBC count increases somewhat in addition to plasma increase BUT hematocrit decreases
**these support greater cardiac output by supporting greater venous return and preload on the heart
**no clear change in hemoglobin leveles in the trained vs untrained

 

How else does training improve performance?

 

-       increased mitochondrial enzyme density in the skeletal muscle (less lactate produced), leads to more ATP provided via oxidative system
-increased lactate removal, potentially making more glucose available for active muscle