Deck 11: Respiration During Exercise

Question 1

Carbon dioxide is transported in arterial blood principally as

A)carbaminohemoglobin.
B)dissolved CO₂ in solution in the blood.
C)bicarbonate.
D)carbon monoxide.

Answer 1

C

Question 2

A by-product of anaerobic glycolysis in red blood cells that shifts the O₂-Hb dissociation curve to the right at high altitude is

A)pyruvate
B)2-3 DPG
C)3-phosphoglycerate
D)phosphoenolpyruvate

Answer 2

B

Question 3

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

A)a significant decline in arterial PO₂.
B)an increase in arterial PCO₂.
C)an increase in arterial pH.
D)a decrease in arterial pH.

Answer 3

D

Question 4

Most of the O₂ contained in the blood

A)exists in solution as a dissolved gas.
B)is bound to hemoglobin as oxyhemoglobin.
C)is in the form of carboxyhemoglobin.
D)is in the form of deoxyhemoglobin.

Question 5

Small changes in arterial PCO₂ have a ______________ effect on ventilation compared to small changes in PO₂.

A)greater
B)lesser
C)the same
D)none of the above answers are correct

Question 6

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

A)chronic obstructive lung disease.
B)impaired alveolar ventilation resulting in hypoventilation.
C)asthma.
D)a diffusion limitation secondary to a rapid red blood cell transit time.

Question 7

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

A)H⁺ of mixed venous blood.
B)PCO₂ and H⁺ of cerebral spinal fluid.
C)PO₂,pH,and PCO₂ of arterial blood.
D)PCO₂ and H⁺ of mixed venous blood.

Question 8

The respiratory control center is located in the

A)medulla oblongata.
B)cerebrum.
C)carotid bodies.
D)cerebellum.

Question 9

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

A)a decrease in alveolar ventilation.
B)an increase in alveolar ventilation.
C)no change in alveolar ventilation.
D)a prolonged breath hold.

Question 10

Activation of rectus abdominis muscles would result in

A)active inspiration.
B)passive inspiration.
C)active expiration.
D)passive expiration.

Question 11

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

A)1 mm Hg of resting values.
B)10-12 mm Hg of resting values.
C)20-25 mm Hg of resting values.
D)30-40 mm Hg of resting values.

Question 12

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

A)less than
B)the same as
C)greater than
D)none of the above answers is correct.

Question 13

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

A)760 mmHg.
B)159 mmHg.
C)125 mmHg.
D)100 mmHg.

Question 14

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

A)a lower arterial PO₂.
B)a higher arterial PCO₂.
C)a significant increase in blood temperature.
D)all of the above answers are correct.

Question 15

Exercise-induced asthma could impair pulmonary gas exchange by

A)reducing blood flow to the lung.
B)lowering the drive to breath.
C)causing bronchodilation.
D)increasing airway resistance.

Question 16

The most important muscle of inspiration is/are the

A)diaphragm.
B)rectus abdominis.
C)internal oblique.
D)external intercostals.

Question 17

An increase in blood temperature and a decrease in blood pH would result in _____________ in the oxyhemoglobin dissociation curve.

A)a rightward shift
B)a leftward shift
C)no change in
D)none of the above answers are correct

Question 18

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

A)anatomical dead space.
B)minute ventilation.
C)alveolar ventilation.
D)tidal volume.

Question 19

The term ventilation refers to the

A)cooling of the airways by respiration.
B)random movement of molecules from an area of high concentration to an area of lower concentration.
C)mechanical process of moving air in and out of the lungs.
D)oxygenation of blood as it travels through the lungs.

Question 20

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

A)a higher
B)a lower
C)the same
D)none of the above answers are correct

Question 21

Research indicates that several months of endurance training results in significant changes in both lung structure and pulmonary function.

Question 22

During exercise,a right shift in the oxyhemoglobin disassociation curve insures that more oxygen is unloaded from hemoglobin to the working muscle compared to rest.

Question 23

The primary drive to increase ventilation during exercise is due to

A)input from peripheral chemoreceptors.
B)input from central chemoreceptors.
C)input from skeletal muscle mechanoreceptors
D)none of the above answers are correct

Question 24

During resting conditions,the intrapleural pressure is typically lower than the intrapulmonary pressure.

Question 25

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

A)tissue area.
B)diffusion coefficient of the gas.
C)difference in partial pressure of the gas on the two sides of the tissue.
D)all of the above answers are correct

Question 26

An increase in alveolar ventilation (at rest)resulting in hyperventilation will reduce arterial ______and increase______.

A)PCO₂,pH
B)O₂,pH
C)pH,PCO₂
D)None of the above questions are correct

Question 27

The pulmonary system does not limit VO₂ max in elite endurance athletes that exhibit exercise-induced hypoxemia.

Question 28

Compared to the oxyhemoglobin dissociation curve,the myoglobin dissociation curve_______.

A)is much steeper at PO₂'s below20 mmHg.
B)reaches a plateau at a much lower PO₂.
C)both A and B are correct
D)none of the above answers are correct

Question 29

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

A)an ideal V/Q ratio for optimal gas exchange.
B)that blood flow is higher than ventilation in this region of the lung.
C)that ventilation is higher than blood flow in this region of the lung.
D)none of the above answers are correct

Question 30

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

A)to cool the airways.
B)to provide an interface for gas exchange between the external environment and the body. c.regulation of acid base balance during exercise.
D)None of the above answers are correct

Question 31

Gas exchange in the lungs occurs

A)across approximately 300 million alveoli.
B)in the conducting zone.
C)in the respiratory zone.
D)both A and C are correct answers

Question 32

Which of the following statements about myoglobin are true?

A)myoglobin binds oxygen.
B)myoglobin shuttles oxygen from the cell membrane to the mitochondria.
C)myoglobin exists in relatively large quantities in slow-twitch muscle fibers.
D)all of the above answers are correct.

Question 33

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

A)movement of sodium molecules out of the red blood cell.
B)movement of chloride molecules out of the red blood cell.
C)movement of chloride molecules into the red blood cell.
D)both A and C are correct

Question 34

Which of the following statements about pulmonary physiology is correct?

A)The PO₂ of inspired air at sea level is approximately 159 mmHg.
B)The percentage of CO₂ in the air is 0.0003.
C)The percentage of O₂ in the air at sea level is the same as at high altitude.
D)All of the above answers are correct

Question 35

According to Dalton's law,the total pressure of a gas mixture is equal to the sum of pressures of each gas in the mixture.

Question 36

The carotid bodies are chemoreceptors that are sensitive to changes in arterial_______.

A)H⁺ and K⁺ concentrations.
B)pH,PCO₂,and PO₂.
C)pH and K⁺ concentrations.
D)PO₂ only.

Question 37

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

A)PO₂ of approximately 100 mmHg.
B)oxyhemoglobin saturation of 97-98%.
C)oxygen content of 20 ml O₂ / 100 ml blood.
D)all of the above answers are correct.