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By studying this chapter, you should be able to do the following:

  1. Describe the primary function of the pulmonary system.

  2. Outline the major anatomical components of the respiratory system.

  3. List the major muscles involved in inspiration and expiration at rest and during exercise.

  4. Discuss the importance of matching blood flow to alveolar ventilation in the lung.

  5. Explain how gases are transported across the blood–gas interface in the lung.

  6. Describe the major transportation modes of O2 and CO2 in the blood.

  7. Discuss the effects of increasing temperature, decreasing pH, and increasing levels of 2–3 DPG on the oxygen–hemoglobin dissociation curve.

  8. Describe the ventilatory response to constant load, steady-state exercise. What happens to ventilation if exercise is prolonged and performed in a hot environment?

  9. Describe the ventilatory response to incremental exercise. What factors contribute to the alinear rise in ventilation at work rates above 50% of V̇O2 max? Further, discuss the change in breathing pattern that occurs when going from rest to exercise at varying intensities.

  10. Discuss the neural components involved in the generation of the rhythm of breathing.

  11. Identify the location and function of chemoreceptors and mechanoreceptors that contribute to the regulation of breathing.

  12. Discuss the neural-humoral theory of ventilatory control during exercise.


Function of the Respiratory System—The Big Picture

Structure of the Respiratory System

  • Conducting Zone

  • Respiratory Zone

Mechanics of Breathing

  • Inspiration

  • Expiration

  • Airway Resistance

Pulmonary Ventilation

Pulmonary Volumes and Capacities

Diffusion of Gases

Blood Flow to the Lung

Ventilation–Perfusion Relationships

O2 and CO2 Transport in Blood

  • Hemoglobin and O2 Transport

  • Oxygen–hemoglobin Dissociation Curve

  • O2 Transport in Muscle

  • CO2 Transport in Blood

Ventilation and Acid–Base Balance

Ventilatory and Blood–Gas Responses to Exercise

  • Rest-to-Work Transitions

  • Prolonged Exercise in a Hot Environment

  • Incremental Exercise

  • Changes in Breathing Pattern during Exercise

Control of Ventilation

  • Ventilatory Regulation at Rest

  • Respiratory Control Center

  • Input to the Respiratory Control Center

  • Ventilatory Control during Moderate-Intensity Exercise

  • Ventilatory Control during Heavy and Very Heavy Exercise

Do the Lungs Adapt to Exercise Training?

Does the Pulmonary System Limit Maximal Exercise Performance?

Key Terms

alveolar ventilation (V̇A)


anatomical dead space

aortic bodies

Bohr effect

bulk flow

carotid bodies

cellular respiration







partial pressure


pulmonary respiration

residual volume (RV)



tidal volume

total lung capacity (TLC)


ventilatory threshold (Tvent)

vital capacity (VC)

The word respiration is often used in two different contexts in physiology: (1) pulmonary respiration and (2) cellular respiration. Pulmonary respiration refers to ventilation (breathing) and the exchange of gases (O2 and CO2) in the lungs. Cellular respiration relates to O2 utilization and CO2 production by the tissues (see Chap. 3). This chapter is concerned with pulmonary respiration, and the term respiration is used in this chapter as a synonym for pulmonary respiration. Because the pulmonary system plays a key role in maintaining ...

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