Ch 9 Stress Flashcards
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.
What physiological response occurs due to alveolar hypoxia?
Pulmonary vasoconstriction
This response increases pulmonary arterial pressure and the work done by the right heart.
What condition is characterized by headache, fatigue, and dizziness at high altitude?
Acute mountain sickness
This condition is attributable to hypoxemia and alkalosis.
What is chronic mountain sickness associated with?
Marked polycythemia, fatigue, reduced exercise tolerance, and severe hypoxemia
This syndrome develops in long-term residents at high altitude.
What is the most important feature of acclimatization to high altitude?
Hyperventilation
What genetic difference is noted in Tibetans compared to Han Chinese?
Higher frequency of the hypoxia-inducible factor 2α (HIF-2α) gene
HIF-2α regulates many physiological responses to hypoxia.
What can happen when high concentrations of O2 are inhaled for extended periods?
Damage to the lung
This can lead to conditions such as pulmonary edema.
What is absorption atelectasis?
Collapse of alveoli due to gas absorption when an airway is obstructed
This occurs even when air is breathed, but the process is slower compared to when 100% O2 is breathed.
True or False: Breathing 100% O2 can lead to retinopathy of prematurity in premature infants.
True
What physiological changes occur due to the absence of gravity in space flight?
More uniform distribution of ventilation and blood flow, increased thoracic blood volume
These changes can lead to improved gas exchange.
What is barotrauma?
Compression of gas cavities due to pressure differences during diving
This can occur if a diver fails to exhale while ascending.
What is decompression sickness caused by?
Formation of N2 bubbles during rapid ascent from a deep dive
What is the treatment for decompression sickness?
Recompression in a chamber
This reduces bubble volume and helps to alleviate symptoms.
What is inert gas narcosis?
CNS effects caused by high partial pressures of N2 during deep dives
Symptoms include euphoria and loss of coordination.
What can excessive O2 exposure lead to in the CNS?
Convulsions
This occurs at high Po2 levels and can be preceded by nausea and twitching.
What are some clinical uses of hyperbaric O2 therapy?
Treatment of CO poisoning, gas gangrene, and decompression sickness
What are the chief pollutants in the atmosphere?
- Nitrogen oxides
- Sulfur oxides
- Ozone
- Carbon monoxide
- Hydrocarbons
- Particulate matter
These pollutants are primarily from vehicle emissions and industrial activities.
What health effects do nitrogen oxides have?
Inflammation of the upper respiratory tract and eye irritation
They are responsible for the yellow haze of smog.
What is the danger associated with carbon monoxide in the atmosphere?
It binds to hemoglobin, reducing oxygen transport
Fill in the blank: The risk of decompression sickness can be reduced by breathing a ______ during the dive.
helium-O2 mixture
What do nitrogen oxides cause in the human body?
Inflammation of the upper respiratory tract and eye irritation
They are also responsible for the yellow haze of smog.
What are the effects of sulfur oxides and ozone on the respiratory system?
Cause bronchial inflammation and pulmonary edema in high concentrations
What is the danger of carbon monoxide (CO)?
It ties up hemoglobin
What pollutants are potentially carcinogenic and found in tobacco smoke?
Cyclic hydrocarbons
What is meant by pollutants acting synergistically?
Their combined actions exceed the sum of their individual actions
How are aerosols defined?
Very small particles that remain suspended in the air
What happens to large particles when inhaled?
Removed by impaction in the nose and pharynx
What is sedimentation in the context of inhaled particles?
Medium-sized particles deposit in small airways due to their weight
Where does heavy deposition of inhaled particles occur?
In the terminal and respiratory bronchioles
What happens to the smallest particles (>0.1 μm) when inhaled?
They may reach the alveoli and some are exhaled
How are particles removed from bronchial walls?
Swept up by the mucociliary escalator and either swallowed or expectorated
What can paralyze ciliary action in the respiratory system?
Inhaled irritants
What engulfs particles deposited in the alveoli?
Macrophages
What is liquid breathing?
Breathing liquid instead of air, possible for some mammals
What is the challenge of breathing liquid compared to air?
Increased density and viscosity, requiring more work to breathe
What is a serious problem when breathing liquid?
Eliminating CO2 due to slower diffusion rates in liquid
What is the Po2 of fetal blood leaving the placenta?
About 30 mm Hg
What is the main difference in circulation between the fetus and adult?
The placenta circulates in parallel with fetal tissues, while the lung circulates in series in adults
What happens to blood flow through the ductus arteriosus (DA) after birth?
It shunts most blood from the pulmonary artery to the descending aorta
What occurs during the first breath of a newborn?
A dramatic fall in pulmonary vascular resistance
What is the role of pulmonary surfactant in newborns?
Stabilizes open alveoli during the first breaths
What is the significance of the closure of the foramen ovale (FO) at birth?
It prevents mixing of oxygenated and deoxygenated blood
What is a key feature of acclimatization to high altitude?
Hyperventilation leading to low arterial Pco2 values
What can happen if a patient breathes a high concentration of O2?
They may develop atelectasis if an airway is obstructed
What is decompression sickness and how does it occur?
Formation of N2 bubbles in the blood after deep diving
What are the mechanisms for the removal of atmospheric pollutants from the lung?
- Mucociliary escalator
- Macrophages
What is the arterial Po2 in the descending aorta of a fetus?
Less than 25 mm Hg
What happens to pulmonary blood flow after the first breath?
It increases due to reduced pulmonary vascular resistance
What is the relationship between exercise and oxygen consumption?
Oxygen consumption increases linearly with work rate up to V·o2 max
What physiological change occurs during exercise regarding ventilation?
There is a large rise in ventilation
What happens to the acid-base status during exercise?
Changes occur due to increased CO2 output
What is the effect of very deep diving on the risk of decompression sickness?
Risk is reduced when using helium-oxygen mixtures
What decreases when a seated astronaut transitions from 1G to 0G?
Blood flow to the apex of the lung
What condition did the 45-year-old man likely experience after ascending quickly while SCUBA diving?
Bubbles of gaseous nitrogen
This condition is commonly known as decompression sickness or ‘the bends’ caused by nitrogen bubbles forming in the body due to rapid ascent.
What is the primary mechanism that explains the symptoms of severe pain, pruritus, and difficulty breathing in the diver?
Bubbles of gaseous nitrogen
The formation of nitrogen bubbles in tissues and blood can lead to various symptoms including joint pain and respiratory issues.
What changes in arterial blood gas would be expected shortly after a 23-year-old woman arrives at the summit of a 4,000 m mountain?
Decreased Po2 and increased Pco2
At high altitudes, the partial pressure of oxygen decreases, leading to lower oxygen saturation and potential increases in carbon dioxide levels due to hypoventilation.
At high altitudes, what happens to the pH of arterial blood?
7.33
This indicates a state of respiratory acidosis, commonly due to hypoventilation at high altitudes.
Which arterial blood gas value represents a state of hypoxia at high altitude?
Po2 of 55 mm Hg
A Po2 value below normal indicates significantly reduced oxygen availability in the blood.
What arterial blood gas change is observed during maximum exercise at sea level for the 48-year-old woman?
Po2 remains at 90 mm Hg
This suggests that at sea level, the oxygen saturation is maintained during exercise.
What is the arterial Po2 value during maximum exercise at 5,400 m for the 48-year-old woman?
38 mm Hg
This significant drop indicates impaired oxygen delivery during exercise at high altitudes.
What mechanism likely accounts for the observed changes in arterial Po2 in the 48-year-old woman at high altitude?
Hypoventilation
Reduced breathing rate or depth can lead to decreased oxygen intake, especially at high altitudes.
Fill in the blank: The phenomenon of rapid ascent in SCUBA diving leading to joint pain and respiratory issues is known as _______.
decompression sickness
Decompression sickness occurs due to nitrogen bubbles forming in the body as pressure decreases during ascent.
True or False: At high altitudes, arterial blood Pco2 typically increases due to hypoventilation.
True
Hypoventilation can lead to elevated carbon dioxide levels in the blood due to insufficient gas exchange.
