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Lecture 6

Respiratory System -- Lecture 6 -- High Altitude and Exercise (Michelle French) PSL 301

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Mandy Wintink

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Louisa Man (notes adapted from Dr. Michelle French) Lecture 6: Respiratory System – High Altitude & Exercise Case Study: High Altitude - Defined as > 1500m - 25% of people at ~2500 get high altitude sickness - HYPOXIA (lack of O2) problem Consider: Barometric pressure at the summit of Mt Everest: 253mmHg PO = barometric pressure x percent of oxygen in air 2 = 253 mmHg x 0.21 = 53mmHg! What are the physiological responses to HYPOXIA? - Recall: ventilation + arterial P2O have a positive relationship (↑ventilation, ↑ arterial P2O ) - At lower PO 2 the relationship (↑ventilation, ↑ arterial PCO2) has a steeper slope In other words, in HYPOXIA (lower PO 2), ventilation increases even at the slight increase/ buildup of arterial PCO2. What are the consequences of hyperventilation? + - CO 2 H O2 H CO2H 3HCO 3 -------------------------------------------------- (Hyperventilation = quickly getting rid of C2, Lack of CO 2hifts equation leftwards, Lowers ↓ H + ↑ pH) (↑ pH requires ↓ PO in2order to saturate Hb) Longer Term Physiological Responses a) Release of ERYTHROPOEITIN—make more RBC! b) Synthesisof 2,3- DPG in RBC 2,3 – DPGoccurs in glycolysis, ↓ affinity of Hb for O 2 Degrades when blood is restored Louisa Man (notes adapted from Dr. Michelle French) Conditions related to high altitude MOUNTAIN SICKNESS HIGH ALTITUDE PULMONARY HIGH ALTITUDE CEREBRAL EDEMA EDEMA - Headache - Lung swelling - Ataxia - Irritability - Shortness of breath o Lose control of - Insomnia - Cough bodily - Breathlessness o Related to movements - Nausea pulmonary - Disorientation - Vomiting hypertension - Coma + death o Bc cerebral - Brain swelling autoregulation - Herniation of brain of blood flow (high intercranial pressure) UNCOMFORTABLE FLUID IN LUNGS FLUID IN BRAIN Ventilation Perfusion matching Ventilation  gas pumped out of alveoli Perfusion  pumping liquid into organ/ tissue local control mechanisms normal mismatch CONSTRICT aroundssels in the area will - ventilation of gas out of alve- ↓ ventilation in alveoli UNDERVENTILATED alveoli matched with perfusion of liquid- within alveoli: ↑ PCO , ↓ PO - blood instead goes to alveoli that into organ/ tissue 2 2 are better ventilated, blood gets better oxygenated Prevention and Treatment Prevention Treatment Acetalozamide: forces kidney to excrete 1. Go to lower altitude (ie more oxygen bicarbonate there) 2. Administer oxygen (um yes more oxygen) Louisa Man (notes adapted from Dr. Michelle Fr
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