Ch 9 Stress Flashcards
(86 cards)
What is the typical resting oxygen consumption for a moderately fit subject?
300 ml·min−1
This can rise to about 3,000 ml·min−1 during exercise.
What is the maximum oxygen consumption (V· O2 max)?
The point above which oxygen uptake becomes constant during exercise.
How much does the resting CO2 output typically increase during exercise?
From 240 ml·min−1 to about 3,000 ml·min−1.
What does the respiratory exchange ratio (R) typically rise to during exercise?
From about 0.8 at rest to 1.0 on exercise.
What is the anaerobic threshold?
A point during exercise where lactic acid is produced, causing a rapid increase in ventilation.
What happens to the diffusing capacity of the lung during exercise?
It increases at least threefold.
What does the Fick equation represent in relation to oxygen uptake?
V O2 = Q (CaO2 - CvO2), indicating the relationship between cardiac output and oxygen content.
What physiological change occurs to the oxygen dissociation curve during exercise?
It shifts to the right due to increased Pco2, H+ concentration, and temperature.
What is the primary stimulus for increased red blood cell production at high altitude?
Hypoxemia.
What is hyperventilation’s role in acclimatization to high altitude?
It increases ventilation to maintain alveolar Po2 despite lower ambient oxygen levels.
How does polycythemia affect oxygen-carrying capacity at high altitude?
It increases hemoglobin concentration, allowing for normal or above normal arterial O2 concentration.
What happens to the pulmonary arterial pressure during high altitude acclimatization?
It increases due to pulmonary vasoconstriction in response to alveolar hypoxia.
True or False: The maximum O2 uptake declines rapidly above 4,600 m (15,000 ft).
True.
Fill in the blank: The barometric pressure decreases with distance above the earth’s surface in an approximately _______ manner.
[exponential]
What physiological changes occur in permanent residents at high altitudes?
Acclimatization, including hyperventilation and polycythemia.
What happens to arterial Po2 and O2 saturation in some permanent residents at high altitudes?
Arterial Po2 may be low, but O2 saturation can be normal or above normal due to polycythemia.
What occurs to the ventilation-perfusion inequality during moderate exercise?
It decreases due to a more uniform distribution of blood flow.
What is the effect of exercise training on skeletal muscle?
Increases the number of capillaries and mitochondria.
What is the typical inspired Po2 at the summit of Mount Everest?
43 mm Hg.
What is the relationship between altitude and inspired Po2?
Inspired Po2 decreases with increasing altitude.
What triggers the release of erythropoietin from the kidney in response to high altitude?
Hypoxemia.
What physiological adaptation occurs in the lungs during high altitude acclimatization?
Rightward shift of the O2 dissociation curve due to increased 2,3-diphosphoglycerate.
What happens to the pH of cerebrospinal fluid (CSF) during acclimatization to high altitude?
Initially rises due to respiratory alkalosis, but returns closer to normal after a few days.
What is the effect of increased viscosity due to polycythemia?
It can be deleterious and may lead to complications.