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Questions and Answers
What causes the O2-Hb dissociation curve to shift to the right during moderate exercise?
What leads to a 30-fold increase in blood flow and a 100-fold rise in muscle metabolic rate during moderate exercise?
What is sensed by carotid bodies during strenuous exercise, leading to hyperventilation?
What stimulates the peripheral chemoreceptors during strenuous exercise?
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Why does ventilation increase at the beginning of exercise?
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What happens to arterial Pco2 and alveolar Po2 during high altitude exposure?
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What happens to the O2-Hb dissociation curve during strenuous exercise?
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What is the effect of high altitude on arterial blood PO2?
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What physiological response occurs at high altitude due to low atmospheric Po2?
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Which factor contributes to acclimatization to high altitude?
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What symptoms are associated with acute mountain sickness?
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In unacclimatized individuals at high altitude, what level does the alveolar Po2 drop to?
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What is the cause of hypoxic hypoxia?
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In which type of hypoxia does cyanosis typically occur?
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What is the distinguishing feature of anaemic hypoxia?
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Which type of hypoxia is also known as 'Ischemic hypoxia'?
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What is the cause of histotoxic hypoxia?
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Which condition is associated with hypercapnia?
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What effect does exercise have on pulmonary blood flow?
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"Eupnoea" refers to:
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"Tachypnoea" is characterized by:
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"Apnoea" can be defined as:
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Study Notes
O2-Hb Dissociation Curve Shift
- The O2-Hb dissociation curve shifts to the right during moderate exercise due to increased levels of carbon dioxide (CO2), reduced pH (lowered oxygen affinity as a result of acidosis), and elevated temperature, facilitating oxygen release to active tissues.
Blood Flow and Metabolic Rate
- Moderate exercise causes a 30-fold increase in blood flow and a 100-fold rise in muscle metabolic rate due to heightened demand for oxygen and nutrients by muscles, stimulating cardiovascular response and redistribution of blood flow.
Carotid Bodies and Hyperventilation
- Carotid bodies sense increased arterial CO2, decreased arterial pH, and increased lactic acid during strenuous exercise, leading to hyperventilation to expel CO2 and regulate blood pH.
Peripheral Chemoreceptors
- During strenuous exercise, peripheral chemoreceptors are stimulated by rising levels of CO2 and decreasing levels of oxygen in the blood, triggering increased respiratory rate.
Ventilation Increase at Exercise Onset
- Ventilation increases at the beginning of exercise due to anticipation of increased physical activity, increased metabolic rate, and the immediate need to supply more oxygen and remove CO2.
High Altitude Physiology
- At high altitude, arterial Pco2 remains relatively stable, while alveolar Po2 decreases due to lower atmospheric pressure leading to less oxygen available for respiration.
O2-Hb Dissociation during Strenuous Exercise
- The O2-Hb dissociation curve shifts to the right during strenuous exercise, promoting more oxygen release to tissues, aided by increased CO2 concentration and metabolic byproducts.
High Altitude and Arterial Blood PO2
- High altitude results in decreased arterial blood PO2 because of reduced ambient oxygen pressure, which impairs oxygen transport to tissues.
Physiological Response to Low Atmospheric PO2
- Low atmospheric Po2 at high altitude triggers hypoxemic hypoxia, leading to increased ventilation, heart rate, and red blood cell production as compensatory mechanisms.
Acclimatization to High Altitude
- Increased erythropoiesis (production of red blood cells) contributes to acclimatization at high altitude, enhancing oxygen-carrying capacity of the blood.
Acute Mountain Sickness Symptoms
- Symptoms of acute mountain sickness include headache, nausea, dizziness, fatigue, and sleep disturbances, often due to rapid ascent to high altitude without adequate acclimatization.
Alveolar Po2 in Unacclimatized Individuals
- In unacclimatized individuals at high altitude, alveolar Po2 can drop to significantly low levels, typically around 40 mmHg or lower.
Hypoxic Hypoxia Cause
- Hypoxic hypoxia is caused by insufficient oxygen availability in the environment, leading to inadequate oxygen supply to tissues.
Cyanosis and Hypoxia
- Cyanosis typically occurs in "anemic hypoxia," where inadequate hemoglobin levels result in decreased oxygen transport and notified tissue color.
Anaemic Hypoxia Feature
- A distinguishing feature of anaemic hypoxia is normal oxygen levels in the blood but deficient hemoglobin, impairing oxygen transport.
Ischemic Hypoxia
- Ischemic hypoxia is also referred to as "stagnant hypoxia," caused by reduced blood flow, often due to vascular obstruction or heart failure.
Histotoxic Hypoxia Cause
- Histotoxic hypoxia results from the inability of cells to utilize oxygen due to toxic substances (e.g., cyanide) interfering with cellular respiration.
Hypercapnia Condition
- Hypercapnia is typically associated with respiratory conditions like chronic obstructive pulmonary disease (COPD) or during periods of inadequate ventilation.
Exercise and Pulmonary Blood Flow
- Exercise enhances pulmonary blood flow, improving gas exchange efficiency and overall oxygen uptake due to increased heart rate and cardiac output.
Terminology Definitions
- "Eupnoea" refers to normal, healthy breathing.
- "Tachypnoea" is characterized by rapid breathing rate.
- "Apnoea" can be defined as a temporary cessation of breathing.
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Description
Test your knowledge on the respiratory adjustments that occur at high altitudes, including changes in pH, PCO2, O2-Hb dissociation curve, cardiac output, pulmonary blood flow, and more. Explore how the body adapts to lower oxygen levels and increased altitude.
