Respiratory System Under Stress Flashcards
What happens fo O2 consumption in exercise?
it increases drastically - can reach 3-6 L/min from a baseline of 250 ml/min
What happens to CO2 production during exercise?
increases drastically - up to 3 L/min from 200 ml/min baseline
During exercise the respiratory quotient can increase to 1 or higher. How can it go over 1?
During exercise you have the production of lactic acid in the skeletal muscles, leading to a metabolic acidosis
this means you’re using the bicarb buffer to deal with the increased H+, leading to more CO2 production than you get from just burning glucose alone
What is VO2 max?
when there is no greater rise in O2 consumption even with increased exercise load
What happens to diffusion capacity during exercise? Measured how?
increases 3-fold
measured as CO uptake per partial pressure gradient
What happens to cardiac output during exercise? Why?
increases 3-4 fold
because both heart rate and stroke volume increase from sympathetic stimulation
What happens to blood pressure during exercise?
systolic increases, but diastolic remains the same, so pulse pressure increases and MAP increases
Why does diastolic decrease or stay the same?
because of sympathetic vasodilation of activated muscles leads to decreased TPR and thus decreased diastolic pressure
What happens to pO2 and pCO2 during exercise?
not much actually - pO2 might rise slightly and pCO2 might decrease slightly
What happens to pH during exercise and why?
usually decreased - lactic acid buildup
What equation can we use to determine the amount of inspired pO2 given an atmospheric pressure?
(atmophseric pressure - 47) x .2093
the 47 is the vapor pressure of water
What is the most critical adaptation for high altitudes?
hyperventilation
What is the hyperventilation driven by at high altitude? Why is this different from usual?
hypoxia! unusual because pCO2 is the usual respiratory drive, but not in this instance
How low can pCO2 be reduced due to the hyperventilation at high altitudes?
8 mmHg
What is the blood’s adaptation for high altitude?
polycythemia - increased RBC numbers in response to hypoxia, increasing the O2 carrying capacity of the blood
How does hypoxia cause polycythemia?
triggers erythopoietin production in the kidneys
What effects does breathing 100% oxygen have?
it’s damaging - breathing it chronically will decrease vital capacity and cause pulmonary edema
also atelectasis
Why does breathing 100% O2 for too long cause atelectasis?
I changes the gas pressure int he alveoli to pO2 of 668, pCO2 45 and pH20 47
comaring this to the venous blood with a pO2 of 55, there is such an enormous diffusional gradient that air will move into the blood so quickly that the alveoli can’t be reventilated in time and they collapse
What are three physiological effects of space flight?
Reduced perfusion inequality of the lung since there’s no gravity
calcium loss from bone bc there’s no weight bearing
postural hypotension on return to earth bc not used to gravity and they’re usually volume depleted
What happens to gas-containing structures like the inner ear and lungs during diving?
they will compress on descent with the increased pressure and expand on ascent with the decreased pressure
What happens in “the bends”?
Nitrogen is poorly soluble in blood but high pressures can force it into solution
the N2 will equilibrate with tissues at high pressure but it will return to the blood at low pressures
So if decompression is too quick, nitrogen will escape from the blood as bubbles causing pain and neurological damage if the bubbles form in the cranial circulation
How can you avoid the bends?
replace the nitrogen with helium (?)
When do we use hyperbaric oxygen as a treatment?
carbon monoxide poisoning
gas gangrene
