Chapter 10: Respiration during Exercise

Which of the following statements are true about the changes in ventilatory patterns during exercise?

-Changes in breathing patterns during exercise are important to ensure that optimal mechanics of breathing are realized during exercise -changes in breathing patterns during exercise are designed to reduce the risk of respiratory muscle fatigue -Increasing tidal volume during exercise ensures that dead space ventilation remains small

In a healthy individual at sea level and at rest, which of following characteristics of arterial blood are correct?

-PO2 of approximately 100 mm Hg -oxyhemoglobin saturation of 97-98% -oxygen content of 20 ml O2/100 ml blood

Which of the following statements about pulmonary physiology is correct?

-The PO2 of inspired air at sea level is approximately 159 mm Hg -the percentage of CO2 in the air is 0.0003 -the percentage of O2 in the air at sea level is the same as at high altitude

Which of the following statements about myoglobin are true?

-myoglobin binds oxygen -myoglobin shuttles oxygen from the cell membrane to the mitochondria -myoglobin exists in relatively large quantities in slow-twitch muscle fibers

According to Fick's law of diffusion, the rate of diffusion of a gas across a tissue is directly proportional to the

-tissue area -diffusion coefficient of the gas -difference in partial pressure of the gas on the two sides of the tissue

During exercise at sea level, young, healthy untrained subjects generally maintain exercise arterial PO2 within

10-12 mm Hg of resting values

Under normal conditions at sea level, the partial pressure of oxygen in the alveoli region of the lung is

100 mmHg

During a graded exercise test, the increase in ventilation during the transition from rest to moderate exercise is achieved by

An increase in both breathing frequency and tidal volume

Which of the following statements about sex differences in breathing are correct?

Both when matched for age and body weight, women have smaller airways compared to men and the energy requirement for breathing during exercise is higher for women compared to men are correct

The central chemoreceptors that influence the control of breathing respond to changes in the

PCO2 and H+ of cerebral spinal fluid

An increase in alveolar ventilation (at rest) resulting in hyperventilation will reduce arterial ______ and increase ______

PCO2; pH

In healthy and untrained subjects, the alinear rise in minute ventilation observed during incremental exercise (i.e., ventilatory threshold) could be due to

a decrease in arterial pH

The exercise-induced hypoxemia that occurs in elite endurance athletes during heavy exercise is likely due to

a diffusion limitation secondary to a rapid red blood cell transit time

At a low PO2, myoglobin has _______________ affinity for O2 than hemoglobin

a higher

A significant increase in blood temperature (i.e. from 37ºC to 39ºC) would result in _____________ in the oxyhemoglobin dissociation curve

a rightward shift

Studies reveal that ventilation drifts upward during constant-load submaximal exercise performed in a hot and humid environment. This is likely due to

a significant increase in body temperature

Contraction of the rectus abdominis muscles would result in

active expiration

The volume of gas that reaches the gas-exchange zone of the lung is termed

alveolar ventilation

A decline in arterial PO2 to 70 mm Hg or below would likely result in

an increase in alveolar ventilation

Carbon dioxide is transported in arterial blood principally as

bicarbonate

Gas exchange in the lungs occurs

both across approximately 300 million alveoli and in the respiratory zone are correct answers

Compared to the oxyhemoglobin dissociation curve, the myoglobin dissociation curve _______

both is much steeper at PO2's below 20 mm Hg and reaches a plateau at a much lower PO2 are correct

The most important muscle of inspiration is/are the

diaphragm

Small increases in arterial PCO2 have a ______________ effect on ventilation compared to small decreases in PO2

greater

In the standing position, blood flow to the base of the lung is ______________ blood flow to the apex

greater than

Exercise-induced asthma could impair pulmonary gas exchange by

increasing airway resistance

Most of the O2 contained in the blood

is bound to hemoglobin as oxyhemoglobin.

The term ventilation refers to the

mechanical process of moving air in and out of the lungs

The respiratory control center is located in the

medulla oblongata

An increase in PCO2 in the blood results in the formation of bicarbonate in the red blood cell. Because bicarbonate carries a negative charge (anion), the removal of negatively charged molecule from the red blood cell is required to prevent an electrochemical imbalance across the cell membrane. This problem is avoided by

movement of chloride molecules into the red blood cell

The primary drive to increase ventilation during exercise is due to

none of these answers are correct

The carotid bodies are chemoreceptors that are sensitive to changes in arterial _______

pH, PCO2, and PO2

Diffusion is defined as

random movement of molecules from area of high concentration to an area of lower concentration

In a pulmonary function test, a FEV1/FVC ratio of 0.60 is

suggestive of any airway obstruction

A ventilation-perfusion (V/Q) ratio of 0.64 would indicate

that blood flow is higher than ventilation in this region of the lung

The right shift in the oxyhemoglobin dissociation curve due to a rise in hydrogen ion concentration is called

the Borh effect

The amount of gas moved per breath is termed

tidal volume

Which of the following is NOT an important function of the pulmonary system?

to cool the airways