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Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition.

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Presentation on theme: "Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition."— Presentation transcript:

1 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Chapter 13 Gas Exchange and Transport

2 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Concentration and Partial Pressure of Respired Gases Partial pressure = Percentage of concentration of specific gas × Total pressure of a gas Daltons law –Total pressure = Sum of partial pressure of all gases in a mixture

3 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Ambient Air O 2 = 20.93% = ~ 159 mm Hg P O 2 CO 2 = 0.03% = ~ 0.23 mm Hg P CO 2 N 2 = 79.04% = ~ 600 mm Hg P N 2

4 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Tracheal Air Water vapor reduces the P O 2 in the trachea about 10 mm Hg to 149 mm Hg.

5 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Alveolar Air Alveolar air is altered by entry of CO 2. Average alveolar P O 2 = 103 mm Hg

6 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Movement of Gas in Air and Fluids Henrys law –Gases diffuse from high pressure to low pressure. Diffusion rate depends upon –Pressure differential –Solubility of the gas in the fluid

7 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Pressure Differential The difference in the pressure of specific gases from the capillary blood to the alveoli dictates the direction of diffusion.

8 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Solubility CO 2 is about 25 times more soluble than O 2. CO 2 and O 2 are both more soluble than N 2.

9 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Gas Exchange in Lungs & Tissues Exchange of gases between lungs and blood and gas movement at the tissue level progress passively by diffusion, depending on their pressure gradients.

10 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Gas Exchange in the Lungs P O 2 in alveoli ~ 100 mm Hg P O 2 in pulmonary capillaries ~ 40 mm Hg Result: O 2 moves into pulmonary capillaries P CO 2 in pulmonary capillaries ~ 46 mm Hg Average arterial blood gases equal –P O mm Hg –P CO 2 40 mm Hg

11 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Pulmonary Disease Gas transfer capacity may be impaired by –Thickening of membrane –Reduction in surface area

12 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Gas Transfer in Tissues Pressure gradients cause diffusion of O 2 into and CO 2 out of tissues.

13 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

14 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Transport of O 2 in the Blood Two mechanisms exist for O 2 transport –Dissolved in plasma –Combined with hemoglobin

15 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Oxygen in Physical Solution For each 1 mm Hg increase, mL O 2 dissolves into plasma. This results in ~ 3 mL of O 2 /liter blood. With 5 L total blood volume = 15 mL dissolved O 2 Dissolved O 2 establishes the P O 2 of the blood. –Regulates breathing –Determines loading of hemoglobin

16 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Oxygen Combined with Hemoglobin Each of four iron atoms associated with hemoglobin combines with one O 2 molecule.

17 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

18 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Oxygen-Carrying Capacity of Hb Each gram of Hb combines with 1.34 mL O 2. With normal Hb levels, each dL of blood contains about 20 mL O 2.

19 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Anemia Affects Oxygen Transport Volume percent (vol%) refers to the milliliters of oxygen extracted from a 100-mL sample of whole blood. Human blood carries O 2 at 14 vol%. Iron deficiency anemia reduces O 2 carrying capacity considerably.

20 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition P O 2 and Hb Saturation Oxyhemoglobin dissociation curve illustrates the saturation of Hb with oxygen at various P O 2 values Percent saturation = 12 vol% / 20 vol% × 100 = 60%

21 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition P O 2 in the Lungs Hb ~ 98% saturated under normal conditions Increased P O 2 doesnt increase saturation.

22 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition P O 2 in Tissues At rest – P O 2 = 40 mm Hg –Venous blood carries ~ 70% of the O 2 content of arterial blood. –Venous blood carries 15 mL O 2 per dL blood. –Tissues have extracted 5 mL O 2 per dL blood.

23 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Arteriovenous O 2 Difference The a- O 2 difference shows the amount of O 2 extracted by tissues. During exercise a- O 2 difference increases up to 3 times the resting value.

24 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Bohr Effect Conditions creating the Bohr effect –Increased P CO 2 –Increased temperature –Increased 2,3-DPG –Decreased pH Cause a shift to the right of the oxyhemoglobin dissociation curve

25 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

26 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

27 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition RBC 2,3-DPG 2,3-DPG is a byproduct of glycolysis/ RBCs contain no mitochondria. –Rely on glycolysis 2,3-DPG increases with intense exercise and may increase due to training. Helps deliver O 2 to tissues

28 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Myoglobin, The Muscles O 2 Store Myoglobin is an iron-containing globular protein in skeletal and cardiac muscle. Stores O 2 intramuscularly Myoglobin contains only 1 iron atom. O 2 is released at low P O 2.

29 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition CO 2 Transport Three mechanisms –Bound to Hb –Dissolved in plasma –Plasma bicarbonate

30 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition CO 2 in Physical Solution ~ 5% CO 2 is transported as dissolved CO 2. The dissolved CO 2 establishes the P CO 2 of the blood.

31 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition CO 2 Transport as Bicarbonate CO 2 in solution combines with water to form carbonic acid. Carbonic anhydrase –Zinc-containing enzyme within red blood cell Carbonic acid ionizes into hydrogen ions and bicarbonate ions.

32 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition CO 2 Transport as Carbamino Compounds CO 2 reacts directly with amino acid mq to form carbamino compounds. Haldane Effect: Hb interaction with O 2 reduces its ability to combine with CO 2. This aids in releasing CO 2 in the lungs.

33 Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition


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