Chapter 17 (Pt. 4) Flashcards
what is the cause of high altitude pulmonary edema?
high altitude = low O2 levels = not enough O2 to use all alveolar capacity
what happens when there’s low O2 levels in high altitude pulmonary edema?
blood flow shuts down to capillaries of alv. that are under-ventilated -> pushing the same blood to fewer vessels
increased hydrostatic pressure pushes more fluid out of open pulmonary capillaries into the alveolar air space
if lymph can’t remove excess fluid -> pulmonary edema -> drown yourself -> need to get to lower altitude asap
why is supplemental oxygen more effective for treating altitude-induced hypoxia than for COPD?
altitude-induced hypoxia: not enough O2
COPD: not enough lung, aka lung damage = destroyed alveoli = if no alveoli to ventilate, increasing PO2 with supplemental O2 won’t increase arterial PO2
why does supplemental O2 increase O2 delivery? (short and long)
short: increases the gradient
long: supplemental O2 increases PO2 delivered to the alveoli to increased O2 gradient to increase O2 diffusion rate.
what is the primary way CO2 is removed from the body?
converted to bicarbonate in RBCs
what are the two other ways CO2 is removed from the tissues?
~10% binds to Hb -> carbamino-Hb (Haldane effect)
~5% of metabolic CO2 is dissolved in plasma
what is the important CO2 equation?
CO2 + H2O <–> H2CO3 <–> HCO3- + H+
in _____, the equation is going to favor moving to the right
tissue
in _____, the equation is going to favor moving to the left
lungs
in tissue, the equation is going to favor moving to the _____
right
is lungs, the equation is going to favor moving to the ____
left
oxygen is transported in the blood (2)
- as molecular oxygen gas dissolved in plasma
- as oxyhemoglobin carried inside RBCs
oxygen is NOT transported in the blood
as molecular oxygen carried inside RBCs
what’s the problem with the sentence: oxygen is transported in blood as molecular oxygen carried inside RBCs
inside RBCs it’s no longer O2!
how do O2 chemosensors work?
- if enough O2, all good!
- if not enough O2, O2 sensor will…
close K+ channels = depolarization = calcium-mediated exocytosis = afferent neuron sends a signal to the brain
how do CO2 chemosensors work?
increases CO2 in bloodstream = diffuses to CSF = carbonic anhydrase in CSF = HCO3- + H+
increase in H+ stimulates pH sensors, which stimulate the brain stem resp. sensors
what’s the main difference between O2 chemosensors and CO2 chemosensors?
O2 is directly measured, CO2 is indirectly measured (measure pH instead)
what is the trigger for increased ventilation under hypoxic conditions?
decreased O2, makes you wanna breathe more
what is the trigger for increased ventilation under normoxic conditions? why?
CO2 buildup. triggers brain stem respiratory sensor. CO2 sensors are more sensitive than O2 sensors
what do “normoxic” conditions refer to?
adequate O2
