Chapter 10: Respiration during Exercise

OBJECTIVES

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 $V˙O2 max$?

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

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

OUTLINE

• Function of the Respiratory System—The Big Picture 225

• Structure of the Respiratory System 225

  • Conducting Zone 227

  • Respiratory Zone 228

• Mechanics of Breathing 228

  • Inspiration 229

  • Expiration 229

  • Airway Resistance 229

• Pulmonary Ventilation 231

• Pulmonary Volumes and Capacities 232

• Diffusion of Gases 234

• Blood Flow to the Lung 236

• Ventilation–Perfusion Relationships 237

• O₂ and CO₂ Transport in Blood 237

  • Hemoglobin and O₂ Transport 237

  • Oxygen–hemoglobin Dissociation Curve 238

  • O₂ Transport in Muscle 240

  • CO₂ Transport in Blood 240

• Ventilation and Acid–Base Balance 241

• Ventilatory and Blood–Gas Responses to Exercise 242

  • Rest-to-Work Transitions 242

  • Prolonged Exercise in a Hot Environment 242

  • Incremental Exercise 242

• Control of Ventilation 244

  • Ventilatory Regulation at Rest 244

  • Respiratory Control Center 244

  • Input to the Respiratory Control Center 245

  • Ventilatory Control during Submaximal Exercise 247

  • Ventilatory Control during Heavy Exercise 248

• Do the Lungs Adapt to Exercise Training? 249

• Does the Pulmonary System Limit Maximal Exercise Performance? 250

KEY TERMS

alveolar ventilation $(V˙A)$

alveoli

anatomical dead space

aortic bodies

Bohr effect

bulk flow

carotid bodies

cellular respiration

deoxyhemoglobin

diaphragm

diffusion

hemoglobin

myoglobin

oxyhemoglobin

partial pressure

pleura

pulmonary respiration

residual volume (RV)

respiration

spirometry

tidal volume

total lung capacity (TLC)

ventilation

ventilatory threshold (Tvent)

vital capacity (VC)

INTRODUCTION

The word respiration is ...