inspiration: air rushes into lungs to balance pressure
after inspiration: thorax is expanded, lung pressure = atmospheric pressure
thorax returns to resting dimensions: lung pressure > atmospheric pressure
expiration: air rushes out of lungs to balance pressure
what does pulmonary diffusion do and where does it occur?
replenishes blood's oxygen supply
removes carbon dioxide from returning venous blood
occus across the thin respiratory membrane
the total pressure of a mixture of gases equals the sum of the partial pressures of the individual gases in the mixture
gases dissolve in liquids in proportion to their partial pressures, depending on their solubilities in the specific fluids and depending on the temperature
standard atmospheric pressure (at sea level)
What is the % Nitrogen, Oxygen, and CO2 in air
What are the partial pressures of Nitrogen, Oxygen, and CO2 at sea level?
N2: 600.7 mmHg
How does O2 excahnge work?
The arterial PO2 is lower than the alveolar PO2 initially (40:105), so O2 rushes into the arterioles so that at the end the venous PO2 is 100. This process occurs in 3/4 sec.
How does CO2 exchange work?
the arterial PO2 is higher than the alveolar PO2 initially (46:40), so CO2 rushes into the lungs so that the end of the venous PO2 is 40. The CO2 pressure difference is so much smaller because of the solubility of CO2.
As you exercise, what happens to the diffusion capacity?
How are O2 and CO2 transported around the body?
O2: < 2% dissolved in plasma (sets up pressure gradient)
-98% chemically combined with Hb in RBCs (4 heme groups to every 1 O2 molecule)
CO2: 7-10% dissolved in plasma
-60-70% chemically combined to make bicarbonate (HCO3-)
-20-33% reacts with globin portion of Hb to make carbamino compounds
What does an increase in H+ and temperature do to affect oxygen transport?
allows more oxygen to be unloaded there.
What environmental factors can affect the % saturation of Hb with O2?
changes with altitude: increase in RBC but lower PO2 (too many trucks, not enough oxygen)
changes with anemia: decrease in RBC (enough oxygen, but not enough trucks)
What are the five factors that affect the saturation of O2 with Hb?
PO2 in blood: down
level of 2,3-DPG in RBC: up
Why do smokers have a hard time getting enough O2?
Because CO they produce binds better to Hb than O2
What is the equation used to find pulmonary ventilation?
Ve = TV * f
shortness of breath
increase in ventilation that exceeds the metabolic need for oxygen
a breathing technique to trap and pressurize air in the lungs, if held for an extending period, it can reduce cardiac output. Used during heavy lifts
What is the ventilatory equivalent for O2, at rest, at max exercise?
ratio between Ve and VO2 in a given time frame
at rest: Ve/VO2 = 23-28 per minute
at max exercise: Ve/VO2 = 30L
Generally it's pretty constant
point during intense exercise at which ventilation increases disproportionately to the oxygen consumption.
due to glycolysis
point during intense exercise at which metabolism becomes more anaerobic
sometimes reflects lactate threshold
seen by increase in Ve/VO2 and no increase in Ve/VCO2
What is the main respiratory limitation to performance?
up to 15% of VO2 goes to breathing during exercise compared to 2% at rest.
ventilation is not usually limiting factor.
How is the acid-base balance maintained?
HCO3- + H+ => H2CO3 => CO2 + H2O
Does pH return to normal faster during passive or active recovery?