Respiratory Changes Pt. 2 Flashcards
The body contains how much stored oxygen that can be used for aerobic metabolism?
About 2L
Where is the body’s stored oxygen located that can be used for aerobic metabolism?
Lungs (.5L)
Body fluids (.25L)
Combined with hemoglobin (1L)
Muscle myoglobin (.3L)
In heavy exercise, how quickly is stored oxygen depleted?
Within 2 minutes
How much oxygen debt can result from heavy exercise?
11.5L
Before oxygen debt is repaired, what two things remain at high levels?
Ventilation and O2 uptake
What type of oxygen debt occurs during the first couple of minutes post exercise?
Alactacid oxygen debt (3.5L)
What type of oxygen debt occurs over 40 minutes post exercise?
Lactic acid oxygen debt (8.0L)
What is associated with alactacid oxygen debt?
Reconditioning of the phosphagen system and replenishing of oxygen stores
What is associated with lactic acid oxygen debt?
Removal of lactic acid
What is a side effect of lactic acid buildup?
Extreme fatigue
What stimulates the first breath at birth?
Cooling of skin and slightly asphyxiated state with elevated CO2
What is necessary to open alveoli on first breath during birth?
40-60cm H2O of negative pleural pressure
Closure of what structures occur at birth to initiate circulatory changes?
Foramen ovale (atria), ductus arteriosus (great vessles), ductus venosus (bypass liver)
How is total peripheral resistance (TPR) affected at birth?
Increased
How is pulmonic resistance affected at birth?
Decreased (elimination of hypoxia)
What is the effect of altitude on barometric pressure?
Decreased barometric pressure as one ascends
At what height is the barometric pressure 47 mmHg (LOW) and the blood “boils”?
63,000 ft
Does the amount of oxygen in the air change with altitude?
NO, the partial pressure does
As barometric pressure decreases, how does PO2 change?
Decreases, as well
How does an unacclimatized person suffer from ascending to great heights?
Deterioration of nervous system function
What are some signs and symptoms of hypoxia due to ascending great heights?
Sleepiness, false sense of well being, impaired judgment, clumsiness, blunted pain perception, decreased visual acuity, tremors twitching, seizures.
What types of edema are seen with acute mountain sickness?
Cerebral and pulmonary
What is the effect of cerebral edema?
Hypoxia and local vasodilatation
What is the effect of pulmonary edema?
Hypoxia and local vasoconstriction
What receptors are stimulated immediately following exposure to low PO2 at high altitude?
Arterial peripheral chemoreceptors due to hypoxia
What condition arises from exposure to low PO2 at high altitude?
Respiratory alkalosis (pH increase)
What effects are demonstrated by the increase in pH seen in respiratory alkalosis?
Inhibition of ventilation and opposes the stimulatory effects of hypoxia on peripheral chemoreceptors
As inhibition fades from respiratory alkalosis, how does ventilation change?
Increases 5X
Why does ventilation increase so much following respiratory alkalosis?
Excretion of HCO3- by kidneys acts to offset decreased CO2 to bring pH back to normal then there is hypoxic unopposed stimulation of peripheral chemoreceptors yet again so ventilation increases
How does chronic mountain sickness affect hematocrit (red cell mass)?
Increased
How does increased hematocrit affect cardiac blood flow?
Increased viscosity makes it harder to pump the blood
What is the effect of chronic mountain sickness on pulmonary arterial blood pressure?
Increased
Hypertrophy of which heart chamber is seen in chronic mountain sickness?
Right ventricle
How is TPR affected by chronic mountain sickness?
Decreased (due to dilation in tissue beds)
What condition can arise from chronic mountain sickness?
Congestive heart failure
Why is chronic mountain sickness dangerous?
Fatal is person is not removed to lower altitude
What is increased during acclimatization to higher altitudes?
Pulmonary ventilation
Hematocrit (RBCs)
Diffusing capacity of lungs
Tissue vascularity, capillary density
Ability of tissues to use O2 (increased mitochondria and cellular oxidative systems)
Synthesis of 2,3-DPG (shifts to dissociation)
Increased synthesis of 2,3-DPG is an advantage for what part of the body? Disadvantage?
Tissues - advantage
Lung - disadvantage
How are people who lives in the Andes and Himalayas able to withstand the high altitudes?
Natural acclimatization that begins in infancy
How do those that live in high altitude locations like the Andes and Himalayas differ?
Increased chest to body ratio
High ratio of ventilatory capacity to body mass
Increased right ventricle
Shift in oxy-hemoglobin dissociation curve
What is the shift seen in the oxy-hemoglobin dissociation curve in those that live in higher altitudes that have naturally acclimatized?
PO2 of 40 mmHg have greater O2 in blood than lowlanders at 95)
Who has a greater work capacity: those naturally acclimatized to high altitudes or well-acclimatized lowlanders at high altitudes?
Naturally acclimatized
How does barometric pressure change as we descend beneath the sea?
Increases tremendously
How do we avoid lung collapse as we descend below sea level?
Air is supplied at high pressures
What is hyperbarism?
Exposing pulmonary capillary blood to extremely high alveolar gas pressures (can be lethal)
What is the effect of high nitrogen partial pressure?
Narcosis in about an hour
When does nitrogen narcosis lead to dysfunction?
Beyond 250 ft below sea level
Nitrogen narcosis is similar to what other sensation?
Alcohol intoxication
How does high PN2 affect function?
Nitrogen dissolves in neuronal membranes and alters ionic conductance
What is the effect of high PO2?
Seizures followed by coma within 30-60 minutes (lethal to divers)
How does high PO2 lead to seizures and coma?
Free radical damage to cell membranes and cellular enzymes
What type of tissue is highly susceptible to damage from high PO2 levels?
Nervous tissue
How can oxygen toxicity be prevented?
If one never exceeds the established maximum depth of a given breathing gas
How do divers avoid oxygen toxicity?
Use hypoxic blends with a lower percentage of O2 than atmospheric air past 180 ft
Increased partial pressure of what gas usually isn’t a problem with depth?
PCO2 (doesn’t increase with depth)
What problems can arise from PCO2 being greater than 80 mmHg?
Depression of respiratory centers Respiratory acidosis Lethargy Narcosis Anesthesia
Why is it necessary to ascend to reduce high levels of PN2?
N2 isn’t metabolized by the body so it remains dissolved in tissues
How long does it usually take for gas pressures of N2 in all body tissues to equilibrate with alveolar PN2?
Several hours
What is decompression?
Increased PN2 due to breathing air under high pressure for an extended period of time
Why does it take a few hours for PN2 equilibration of tissues?
Blood doesn’t flow rapidly enough and N2 doesn’t diffuse rapidly enough
Does N2 dissolve faster in water or fat?
Water (less than 1 hour)
How does decompression sickness affect the circulatory system?
Nitrogen out of fluids creating bubbles that can block many blood vessels (small ones first, then larger ones)
What are the signs of symptoms of decompression sickness?
Pain in joints, muscles of arms and legs
Nervous system issues like dizziness, paralysis, unconsciousness
How is decompression sickness prevented?
Gradual ascent from lower levels to allow time for body to acclimate (total decompression time = 3 hours)
The lung ranks second as an organ of body metabolism behind what other organ?
Liver
What is the advantage that the lung has over the liver when it comes to metabolism?
All blood passes through the lungs with every complete cycle
What organs receive the greatest blood flow per gram of tissue?
Kidneys (due to their filtration function)
What are examples of the lung’s metabolic function?
Angiotensin I converted to angiotensin II
Prostaglandins inactivated in one pass through pulmonary circulation
