Student%20Lecture%2014%20Pulmonary%20Exercise%20and%20Altitude

Student%20Lecture%2014%20Pulmonary%20Exercise%20and%20Altitude

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Unformatted text preview: Lecture 14 Lecture Exercise and Altitude Thursday 2­25­10 Outline Outline Announcements – Quiz #8 (on blackboard, email a completed quiz to me on 3­2­10 no later than 2:45pm) – Midterm (on blackboard, email a completed test to me on 3­4­10 no later than 2:45pm) – Grant Assignment 3 (email a completed grant 3 assignment to me on 3­11­10 no later than 1:30pm) – Exercise/Altitude Lecture How is O2 transported from the How is O lung to skeletal muscle? O2 Transport in the Blood Approximately 99% of O2 is transported in the blood bound to hemoglobin (Hb) 280 million Hb molecules Hb4 + 4O2 Hb4O8 – Oxyhemoglobin: O2 bound to Hb – Deoxyhemoglobin: O2 not bound to Hb McArdle, Katch & Katch Relationship between partial pressure of O2 and Hb saturation pressure At rest Hb remains 75% saturated after perfusing skeletal muscle Fig 10.15 Oxyhemoglobin dissociation curve and acute exercise and With exercise muscle PO2 is decreased and more oxygen is released from Hb. exercise Fig 10.15 O2-Hb Dissociation Curve: -Hb Effect of pH Effect Fig 10.16 O2-Hb Dissociation Curve: -Hb Effect of temperature Effect Fig 10.17 Relationship of myoglobin to hemoglobin hemoglobin Acts as site of O2 storage. Fig 10.18 Releases O2 at very low PO2 How is CO2 transported from the How is CO working skeletal muscle to the lung? CO2 Transport in Blood CO Bicarbonate (70%) – CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3­ Transport of CO2 into blood Transport Carbonic anhydrase Carbonic acid dissociates to hydrogen ion and bicarbonate ion. – Bicarbonate moves out of RBC and chloride moves in to RBC to maintain electrochemical balance. Fig 10.19 Transport of CO2 out of blood Transport Oxygen binds to hemoglobin and releases hydrogen ion. Carbonic acid dissociates to water and carbon dioxide Fig 10.20 What would be a potential way to increase What would be a potential way to increase blood pH? What happens to VE, PO2 and What happens to V PCO2 when going from rest to steady state exercise? Rest-to-Work Transitions Rest-to-Work PO2 and PCO2 are maintained – Then, a slower rise toward steady­state Fig 10.21 How does temperature impact How does temperature impact ventilation during prolonged steady state exercise? Exercise in a Hot Environment Exercise During prolonged submaximal exercise: Fig 10.22 Does ventilation increase linearly with Does ventilation increase linearly with increasing workload? Incremental Exercise Incremental Linear increase in ventilation – Up to ~50­75% VO2max Ventilatory threshold (Tvent) – Inflection point where VE increases exponentially Fig 10.23 How is ventilatory threshold altered with How is ventilatory threshold altered with chronic exercise training? Ventilatory Response to Exercise: Ventilatory Trained vs. Untrained In the trained runner, In the trained runner, – pH maintained at a higher work rate – Tvent occurs at a higher work rate Fig 10.23 How is ventilation controlled? How is ventilation controlled? Control of Ventilation Control Inspiratory neurons Expiratory neurons – Acts on rhythmicity area to regulate tidal volume Apneustic area Pneumotaxic area Fig 10.24 Humoral Input to the Respiratory Control Centers Control Central Chemoreceptors Peripheral Chemoreceptors – Aortic bodies – Carotid Bodies Fig 10.25 Neural Input to the Respiratory Control Centers Control Efferent Input Afferent Input Muscle spindles, Golgi tendon organ, joint pressure receptors H+ and potassium Right ventricle Pressure receptors What chemical stimulus impacts the What chemical stimulus impacts the regulation of breathing most? Small changes in PCO2 produce Small dramatic changes in ventilation dramatic Fig 10.26 Fig 10.27 What are the effects of altitude on What are the effects of altitude on ventilation? Altitude and Barometric Pressure Altitude 429mmHg Sea level 760mmHg Mt. Shasta 14,000 ft Effects of altitude on ventilation Effects Increased altitude decreases in PO2. Fig 24.3 ...
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