Gas exchange Flashcards
movement of gases bw two compartments
gas exchange
what are the two locations where gas exchange occurs?
respiratory membrane and systemic capillary wall
in the respiratory membrane, the gases move between what locations?
alveolar air and the plasma in the pulmonary circuit
in the systemic capillary wall, gases move between what locations?
plasma and ISF in the systemic circuit
gases move across barriers by
simple diffusion
gas exerts its pressure independently of other gases, and gas press is proportional to temp and concentration
dalton’s law
pressure exerted by a gas is called
partial pressure (Px)
what is the formula for partial pressure?
Px=Fx(Ptot)
during gas exchange, each gas will move down its partial pressure gradient from…
higher to lower pressure
if the partial pressure is the same in two compartments, then the partial pressure is..
at equilibrium = no net movement bw compartments
movement down a partial pressure gradient can occur from several mediums like what?
from a gas to a liquid, from a liquid to a gas, and from one liquid to another
what is typical resting Po2 and Pco2 within the alveolar air?
100mmHg and 40mmHg
plasma entering a pulmonary capillary has a typical Po2 and Pco2 of
40mmHg and 46mmHg
the partial pressure gradient for O2 favors what movement?
movement of O2 from alveolar air to plasma
the partial pressure gradient for CO2 favors what movement?
movement of CO2 from plasma to alveolar air
diffusion of gases across the respiratory membrane is _______, and the alveolar air and plasma reach ___________ before blood exits pulmonary capillary.
rapid; equillibrium
plasma exiting the pulmonary capillary had a Po2 and Pco2 of what?
100mmHg and 40mmHg
what kind of gas exchange occurs before blood enters the systemic capillaries?
none
plasma entering a systemic capillary has a typical Po2 and Pco2 of
100mmHg and 40 mmHg
ISF will have a ________ value for Po2 and _________ value for Pco2. why is that?
lower; higher; cells take up o2 from the ISF and excrete co2 into the ISF (amount depends on metabolic activity of the cells)
what is a typical Po2 and Pco2 for ISF?
40 and 46 mmHg
the partial pressure gradient for o2 in the systemic capillaries favors
movement from plasma to ISF
the partial pressure gradient for co2 in the systemic capillaries favors
movement from ISF to plasma
plasma exiting the systemic capillary has a Po2 and Pco2 of
40mmHg and 46mmHg
alveolar air has a _______ Po2 and a ________Pco2 than the atmosphere
lower; higher
dry air has a Po2 and Pco2 of what?
160 and 0.3 mmHg
what are the factors that determine the value of alveolar Po2 and Pco2?
Po2 of the atmosphere, the rate of alveolar ventilation, and the rate of total body O2 consumption
when does Po2 decrease?
w increasing altitude
when altitude changes, what changes and what stays the same?
the proportion of the pressures stays the same but the total pressure decreases
what is ventilation rate? how does it affect alveolar Po2?
the amount of air being moved in and out of the lungs per unit time; an increase in ventilation rate will increase alveolar Po2
when does increased O2 consumption occur? how does it affect Po2?
increased metabolic activity (like exercise); cells utilize more O2, so it will decrease Po2
of the factors that affect partial pressures, which one least affects Pco2?
altitude
increased ventilation rate will have what effect on Pco2?
decrease Pco2
how will increased O2 consumption effect Pco2?
increase Pco2
