Respiratory System Under Stress Flashcards
Fick equation
CO = O2 consumption/[pO2arterial - pO2venous]
pCO2 during exercise
decreases slightly
due to hyperventilation in preparation
Blood pressure changes in exercise
systolic pressure increased due to increased contractility
diastolic pressure decreases due to decreased peripheral resistance
Why does blood not flow to lungs in the fetal heart
low O2 in amniotic fluid
⇒ vasoconstriction
⇒ high resistance to flow
lungs are collapsed
Pathophysiology of the decompression sickness
N2 air emboli form from coming up too fast
N2 dissolved in plasma at high pressures
coming up faster than N2 can be breathed out can cause air emboli to form
brain or heart ⇒ death
Respiratory quotient equation
R = CO2 expired / O2 consumed
Tx of decompression sickness
100% O2 until hyperbaric O2 chamber is available
How does R (respiratory quotient) become > 1
acidosis via anaerobic metabolism
creates H+
pushes equilibrium to make CO2
CO2 comes from HCO3-
H+ + HCO3- ⇔ H2CO3 ⇔ H2O + CO2
Fetal Oxygenation
route
umbilical vein → right atrium
Most:
right atrium → foramen ovale → left atrium → left ventricle → aorta → systemic circulation
Some:
Right atrium → pulmonary artery → ductus arteriosis → aorta → systemic circulation
When is hypoxia the main driver of ventilation rate
COPD
high altitude
Fick equation purpose
determine cardiac output
using O2 consumed and difference between arterial and venous O2 concentration
pO2 during exercise
stays the same or increases slightly
due to hyperventilation in preparation
Most important adaptation in high altitude
hyperventilation
hypoxia driven
Acute mountain sickness
consequences
metabolic alkalosis
(hyperventilating)
hypoxia
VO2 max definition
point where no more O2 can be consumed
even at higher work loads
