Question 1

Which of the following circulatory changes are expected during exercise? Rate and strength of cardiac contractions increase
Blood vessels in working muscles constrict
Blood vessels of peripheral vascular system dilate
Blood vessel of heart and brain constrict

Accepted Answer

During exercise, the rate and strength of cardiac contractions increase to pump more blood and thus oxygen and nutrients to the muscles. Blood vessels in working muscles actually dilate (not constrict) to allow for increased blood flow, and similarly, blood vessels in the heart and brain do not constrict; they may dilate or remain unchanged to ensure these critical organs receive sufficient blood supply. Therefore, the only correct statement is that the rate and strength of cardiac contractions increase.

Question 2

At what exercise level would the alveolar-arterial PO₂ difference be expected to change?

Accepted Answer

The alveolar-arterial (A-a) oxygen gradient is expected to increase with exercise, particularly when reaching or exceeding 40% of maximum oxygen consumption, due to factors like ventilation/perfusion mismatch and diffusion limitation.

Question 3

During heavy exercise, what change in perfusion to working muscles can occur?

Accepted Answer

During heavy exercise, the perfusion to working muscles can increase up to 25-fold to meet the increased demand for oxygen and nutrients.

Question 4

During heavy exercise, what change in cardiac output may occur?

Accepted Answer

The answer of During heavy exercise, what change in cardiac...

Question 5

Which of the following pathways likely contribute to increased ventilation during exercise? 
I. Cerebral cortex
II. Proprioceptors in moving muscles, tendons and joints
III. increased body temperature

Accepted Answer

All three pathways contribute to increased ventilation during exercise. The cerebral cortex initiates changes in anticipation of physical activity, proprioceptors in muscles and joints provide feedback on movement, and increased body temperature can stimulate respiratory centers to increase ventilation.

Question 6

What is the term for the point at which the energy pathways that produce lactic acid start to operate?

Accepted Answer

The anaerobic threshold refers to the point during exercise at which the body starts to accumulate lactic acid in the muscles more quickly than it can be removed, indicating a shift from aerobic to anaerobic metabolism.

Question 7

During exercise, how much variation would be expected to occur in the systolic blood pressure?

Accepted Answer

The answer of During exercise, how much variation would be...

Question 8

In healthy adults at rest on F_IO₂ 0.21, what does the mean alveolar-arterial oxygen tension difference equal?

Accepted Answer

In healthy adults at rest breathing room air (FIO2 0.21), the normal alveolar-arterial (A-a) oxygen gradient is typically around 5-15 mm Hg, with 10 mm Hg being a common average value.

Question 9

What is the formula for calculating the maximum heart rate?

Accepted Answer

The most commonly used formula for calculating maximum heart rate is 220 minus the person's age in years.

Question 10

By what amount can ventilation increase during strenuous exercise?

Accepted Answer

During strenuous exercise, ventilation can increase up to 20-fold to meet the increased oxygen demand and carbon dioxide removal needs of the body.

Question 11

During heavy exercise, what percent of the maximal exercise level is reached during the second stage?

Accepted Answer

During heavy exercise, the second stage typically reaches 60-70% of the maximal exercise level. This stage is characterized by a more significant increase in heart rate and breathing as the body starts to work harder to meet the increased demand for oxygen.

Question 12

What changes in arterial blood gases would be expected to occur during very heavy exercise? PaO₂ would decline PaCO₂ would decline PH would decline

Accepted Answer

During very heavy exercise, PaCO2 would decline due to increased ventilation, and pH would decline due to the accumulation of lactic acid and other metabolic byproducts. PaO2 typically remains stable or may slightly increase due to increased ventilation.

Question 13

Why would stroke volume increase during exercise? 
I. Parasympathetic discharge increases cardiac contractility
II. Vasodilation of working muscles increases venous return to the heart
III. Vasoconstriction of peripheral venous blood reservoirs increases venous return

Accepted Answer

II and III are correct because during exercise, vasodilation in working muscles increases venous return to the heart, and vasoconstriction of peripheral venous reservoirs also increases venous return, both of which can lead to an increase in stroke volume. Parasympathetic activity typically decreases during exercise, while sympathetic activity increases, enhancing cardiac contractility and heart rate, not parasympathetic discharge.

Question 14

What changes in ventilatory pattern would be expected during the third stage of moderate exercise?

Accepted Answer

During the third stage of moderate exercise, alveolar ventilation stabilizes as the body reaches a steady state where oxygen demand and carbon dioxide production are balanced by ventilation.

Question 15

When, in the first stage of moderate exercise, is there an increase in alveolar ventilation?

Accepted Answer

Alveolar ventilation increases almost immediately within seconds after the onset of moderate exercise to meet the increased oxygen demand and carbon dioxide removal needs of the body.

Question 16

During heavy exercise, what percent of the total oxygen consumption is consumed by the skeletal muscles?

Accepted Answer

During heavy exercise, skeletal muscles can consume up to 95% of the total oxygen consumption to meet the increased demand for ATP production through aerobic respiration.

Question 17

How does the Frank-Starling curve affect stroke volume during exercise?

Accepted Answer

The Frank-Starling law of the heart states that the stroke volume of the heart increases in response to an increase in the volume of blood filling the heart (the end diastolic volume) when all other factors remain constant. During exercise, increased venous return fills the cardiac chambers more, which according to the Frank-Starling mechanism, allows the heart to contract more forcefully, thereby increasing stroke volume.

Question 18

At rest, what percent of the total oxygen consumption is consumed by the skeletal muscles?

Accepted Answer

The answer of At rest, what percent of the total...

Question 19

What primary factor is responsible for the normal change in oxygen diffusion capacity during maximum exercise?

Accepted Answer

The primary factor responsible for the normal increase in oxygen diffusion capacity during maximum exercise is the increased cardiac output, which leads to the recruitment of additional pulmonary capillaries. This recruitment allows for a greater surface area for oxygen exchange, enhancing the body's ability to uptake oxygen during periods of high demand.

Question 20

What effect does maximum exercise have on oxygen diffusion capacity?

Accepted Answer

During maximum exercise, the oxygen diffusion capacity can increase up to 3-fold due to increased cardiac output and pulmonary blood flow, enhancing the efficiency of oxygen exchange between the lungs and blood.

Quiz 18: Exercise and Its Effects on the Cardiopulmonary System

Which of the following circulatory changes are expected during exercise? Rate and strength of cardiac contractions increase Blood vessels in working muscles constrict Blood vessels of peripheral vascular system dilate Blood vessel of heart and brain constrict

At what exercise level would the alveolar-arterial PO2 difference be expected to change?