RESPIRATORY REGULATION DURING EXERCISE

1. CHAPTER9 CHAPTER 8 RESPIRATORY REGULATION DURING EXERCISE RESPIRATORY REGULATION DURING EXERCISE

2. w Discover how your respiratory system regulates your breathing and gas exchange. Learning Objectives w Find out how the respiratory system brings oxygen to muscles and tissues and rids the body of excess carbon dioxide. w Learn the steps involved in respiration and gas exchange.

3. Respiration Respiration—delivery of oxygen to and removal of carbon dioxide from the tissue External respiration—ventilation and exchange of gases in the lung Internal respiration—exchange of gases at the tissue level (between blood and tissues)

4. External Respiration External Respiration: Pulmonary ventilation—movement of air into and out of the lungs—inspiration and expiration Pulmonary Ventilation External Respiration: Pulmonary diffusion—exchange of oxygen and carbon dioxide between the lungs and blood External and Internal Respiration Video

5. THE RESPIRATORY SYSTEM

6. INSPIRATION AND EXPIRATION

7. Pulmonary Diffusion w Replenishes blood's oxygen supply that has been depleted for oxidative energy production w Removes carbon dioxide from returning venous blood • Occurs across the thin respiratory membrane • Pulmonary Diffusion

8. THE RESPIRATORY MEMBRANE

9. Laws of Gases Dalton's Law: The total pressure of a mixture of gases equals the sum of the partial pressures of the individual gases in the mixture.

10. Partial Pressures of Air w Standard atmospheric pressure (at sea level) = 760 mmHg w Nitrogen (N2) is 79.04% of air; the partial pressure of nitrogen (PN2) = 600.7 mmHg (760 mmHg ´ 0.7904) w Oxygen (O2) is 20.93% of air; PO2 = 159.1 mmHg w Carbon dioxide (CO2) is 0.03%; PCO2 = 0.2 mmHg

11. Did You Know…? Differences in the partial pressures of gases in the aveoli and in the blood create a pressure gradient across the respiratory membrane. This difference in pressures leads to diffusion of gases across the respiratory membrane. The greater the pressure gradient, the more rapidly oxygen diffuses across it.

12. w Gases diffuse along a pressure gradient, moving from an area of higher pressure to lower pressure. (continued) Key Points Pulmonary Diffusion w Pulmonary diffusion is the process by which gases are exchanged across the respiratory membrane in the aveoli to the blood and vice versa. w The amount of gas exchange depends on the partial pressure of each gas.

13. Key Points Pulmonary Diffusion w Oxygen diffusion capacity increases as you move from rest to exercise. w The pressure gradient for carbon dioxide exchange is less than for oxygen exchange, but carbon dioxide’s membrane solubility is 20 times greater than oxygen, so CO2 crosses the membrane easily.

14. Oxygen Transport w Hemoglobin concentration largely determines the oxygen-carrying capacity of blood (>98% of oxygen transported). w Increased H+ (acidity) and temperature of a muscle allows more oxygen to be unloaded there. w Training affects oxygen transport in muscle.

15. - THE a-vO2 DIFF ACROSS THE MUSCLE Rest Maximal exercise

16. - The increase in a-vO2 diff during strenuous exercise reflects increased oxygen use by muscle cells. This use increases oxygen removal from arterial blood, resulting in a decreased venous oxygen concentration. Did You Know…?

17. Factors of Oxygen Uptake and Delivery 1. Oxygen content of blood 2. Amount of blood flow 3. Local conditions within the muscle AVO2 difference video

18. THE VENTILATORY RESPONSE TO EXERCISE

19. Breathing Terminology Dyspnea—shortness of breath. Hyperventilation—increase in ventilation that exceeds the metabolic need for oxygen. Voluntary hyperventilation, as is often done before underwater swimming, reduces the ventilatory drive by increasing blood pH. Valsalva maneuver—a breathing technique to trap and pressurize air in the lungs to allow the exertion of greater force; if held for an extending period, it can reduce cardiac output. This technique is often used during heavy lifts and can be dangerous in certain people under certain conditions.

20. Ventilation tends to match the rate of energy metabolism during mild steady-state activity. Both vary in proportion to the volume of oxygen consumed (VO2) and the volume of carbon dioxide produced by the body (VE). . . Did You Know…?

21. . w When work rate exceeds 55% to 70% VO2max, oxygen delivery can no longer match the energy requirements so energy must be derived from anaerobic glycolysis. The Ventilatory Breakpoint w The point during intense exercise at which ventilation increases disproportionately to the oxygen consumption. W Anaerobic glycolysis increases lactate levels, which increase CO2 levels (buffering), triggering a respiratory response and increased ventilation. **blood lactate, lactic acid that appears in the blood as a result of anaerobic metabolism when oxygen delivery to the tissues is insufficient to support normal metabolic demands. The respiratory response to exercise

22. . . VE AND VO2 DURING EXERCISE

23. . . • Identified by noting an increase in VE/VO2 without an concomitant increase in the ventilatory equivalent for carbon dioxide (VE/VCO2) • Anaerobic threshold • Lactate Threshold and VO2 max • Training VO2 max and anaerobic threshold . . Anaerobic Threshold w Point during intense exercise at which metabolism becomes increasingly more anaerobic w Reflects the lactate threshold under most conditions, though the relationship is not always exact

24. . . . . VE/VCO2 AND VE/VO2

25. w Ventilation increases at the initiation of exercise due to inspiratory stimulation from muscle activity. As exercise progresses, increase in muscle temperature and chemical changes in the arterial blood further increase ventilation. (continued) Key Points Pulmonary Ventilation w The respiratory centers in the brain stem set the rate and depth of breathing. w Chemoreceptors respond to increases in CO2 and H+ concentrations or to decreases in blood oxygen levels by increasing respiration.

26. w Anaerobic threshold is identified as the point at which VE/VO2 shows a sudden increase, while VE/VCO2 stays stable. It generally reflects lactate threshold. . . . . Key Points Pulmonary Ventilation w Unusual breathing patterns associated with exercise include dyspnea, hyperventilation, and the Valsalva maneuver. w During mild, steady-state exercise, ventilation parallels oxygen uptake. w The ventilatory breakpoint is the point at which ventilation increases disproportionally to the increase in oxygen consumption.

27. Respiratory Limitations to Performance w Respiratory muscles may use more than 15% of total oxygen consumed during heavy exercise and seem to be more resistant to fatigue during long-term activity than muscles of the extremities. w Pulmonary ventilation is usually not a limiting factor for performance, even during maximal effort, though it can limit performance in highly trained people. w Airway resistance and gas diffusion usually do not limit performance in normal healthy individuals, but abnormal or obstructive respiratory disorders can limit performance.

28. ARTERIAL BLOOD AND MUSCLE pH

29. RECOVERY AND BLOOD LACTATE LEVELS

30. Chapter 13-5 minutes w a partner • What did you learn after reading Chapter 13 • Overload principle • Specificity principle • Individual differences principle • reversibility • What does the text say are beneficial ways to improve your aerobic capacity? • What does the text say are beneficial ways to improve your anaerobic capacity? • What did you find surprising from the text? • Improve your VO2 max