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					                                         CHAPTER 17

             FUNCTIONAL CAPACITY OF THE CARDIOVASCULAR SYSTEM
DEFINE KEY TERMS AND CONCEPTS

1   Cardiac output


2   Heart rate


3   Stroke volume


4   Mixed venous blood


5   Arteriovenous oxygen difference


6   Direct Fick


7   Indicator dilution method


8   CO2 rebreathing method


9   End-diastolic volume


10 Preload


11 Starling’s law of the heart


12 Afterload


13 Blood shunting


14 Functional residual volume of blood


15 Cardiovascular drift
STUDY QUESTIONS

CARDIAC OUTPUT
Cardiac output = _________ x ________ .


Measurement of Cardiac Output
List 3 methods for measuring cardiac output.
1.

2.

3.

Direct Fick Method
Write the equation for determining cardiac output using the Fick procedure.

                                                                -1
Calculate cardiac output for a person with a VO2 of 400 mL•min and a-v O2 difference of 7 mL
           -1
O2•100•mL .




Indicator Dilution Method
Describe the rationale for the indicator dilution method for cardiac output measurement.




CO2 Rebreathing Method
List 2 advantages of the CO2 rebreathing method for determining cardiac output.
1.

2.

CARDIAC OUTPUT AT REST
Untrained
Give a typical resting cardiac output value for an untrained adult male and female.

Male:

Female:

Endurance Athletes
Does resting cardiac output differ between trained and untrained individuals? Explain in terms of the
differences in the components of the cardiac output equation.
CARDIAC OUTPUT DURING EXERCISE
Draw and label the relationship between cardiac output during progressively increasing exercise oxygen
consumption.




        Stroke Volume,
               -1
        mL•min




                                                                 -1
                                          Oxygen Uptake, L•min


How can aerobically trained athletes achieve a higher maximum cardiac output than untrained persons
despite their slightly reduced maximum heart rate?




Give the approximate difference in maximum exercise cardiac output between trained and untrained
individuals.



Stroke Volume: Systolic Emptying Versus Diastolic Filling
Give 3 physiologic mechanisms for increasing the heart’s stroke volume during exercise.
1.

2.

3.

Enhanced Diastolic Filling
Explain the main point of Starling’s law of the heart.




Greater Systolic Emptying
What physiologic mechanism accounts for the progressive increase in stroke volume during graded
upright exercise?
Cardiovascular Drift: Reduced Stroke Volume and Increased Heart Rate During Prolonged
Exercise
Give the most likely explanation for the progressive downward drift in stroke volume as heart rate
increases in prolonged steady-rate exercise.




CARDIAC OUTPUT DISTRIBUTION
Blood generally flows to tissues in proportion to their ___________ activity.

Blood Flow at Rest
At rest, what percentage of the cardiac output flows to muscle tissue?


Blood Flow During Exercise
Indicate the percentage distribution of cardiac output to active muscle tissue during light, moderate, and
strenuous exercise.

Light exercise:

Moderate exercise:

Strenuous exercise:

Redistribution of Blood Flow
These two body tissues, ___________ and _____________ , cannot tolerate a reduction in blood flow.

Blood Flow to the Heart and Brain
Discuss whether blood flow to the myocardium increases with increasing exercise intensity.




CARDIAC OUTPUT AND OXYGEN TRANSPORT
Rest
How much oxygen is transported in each liter of a healthy person’s blood?



Exercise
For a cardiac output of 5 L min-1, how much total oxygen moves through the body each minute?



Close Association Between Maximum Cardiac Output and VO 2max
Describe the relationship between VO2max and maximum cardiac output.
Cardiac Output Differences Among Men and Women and Children
Give one reason why females have a larger cardiac output compared to males at the same absolute sub-
maximum VO2?



Oxygen Extraction: The a-vO2 Difference
Write the equation for calculating the a-vO2 difference.



List the 2 mechanisms for increasing exercise oxygen consumption.
1.

2.

a-vO2 Difference During Rest
Give a typical a-vO2 difference during rest.



At rest, how much of the oxygen returns “unused” to the heart in the mixed-venous blood?



a-vO2 Difference During Exercise
How many times above the resting value does the a-vO2 difference increase during near-maximal
exercise?



Severe Heart Disease
How can a CHD patient improve aerobic capacity if individuals with this disease experience minimal
training improvement in maximum cardiac output?




Factors that Affect the Exercise a-vO2 Difference
List 2 factors that determine the capacity for oxygen extraction during exercise.
1.


2.

CARDIOVASCULAR ADJUSTMENTS TO UPPER BODY EXERCISE
Maximal Oxygen Consumption
VO2max attained during arm exercise differs by about ________ percent compared to leg exercise.

Submaximal Oxygen Consumption
Outline the general trend for the difference in submaximal VO 2 during arm compared to leg exercise at
similar submaximal exercise power outputs?
Physiologic Response
List 3 physiologic variables that are larger during submaximal upper- compared to lower-body exercise at
the same oxygen consumption.
1.

2.

3.

Implications
In terms of physiologic response, what is the main point the exercise specialist should know when
designing an exercise program using upper- and lower-body exercise?

				
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