Chapter 10

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

False

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

False

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

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

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

a higher

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

alveolar ventilation.

Carbon dioxide is transported in arterial blood principally as

bicarbonate

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

greater

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

impaired alveolar ventilation resulting in hypoventilation.

Most of the O2 contained in the blood

is bound to hemoglobin as oxyhemoglobin.

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

suggestive of 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 amount of gas moved per breath is called

tidal volume.

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. all of the above answers are correct

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

to cool the airways.

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.

1

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

2-3 DPG

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

Which of the following statements about pulmonary physiology is correct?

The PO2 of inspired air at sea level is approximately 159 mmHg. 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. All of the above answers are correct

True or false? 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.

True

True or false? 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.

True

True or false? During resting conditions, the intrapleural pressure is typically lower than the intrapulmonary pressure.

True

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.

An increase in blood temperature and a decrease in blood pH 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 blood temperature.

Gas exchange in the lungs occurs

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

Activation of rectus abdominis muscles would result in

active expiration.

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

an increase in alveolar ventilation.

The most important muscle of inspiration is/are the

diaphragm

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.

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

is much steeper at PO2's below20 mmHg. reaches a plateau at a much lower PO2. both A and B are correct

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.

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. all of the above answers are correct.

The primary drive to increase ventilation during exercise is due to

none of the above answers are correct

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

pH, PCO2, and PO2.