Gas Exchange: Johnson Flashcards
Pressure gradients created by muscular contraction allow for the air to travel into the lungs to get to the alveoli.
???
the partial pressure of the gases in the alveolar air space and in the pulm capi perfusing the alveoli will determine the movement of the air
Alveolar ventilation is what?
product of vt and frequecy gives oupulm vent
The PP of the CO2 and O2 will favor the goal. So O2 will always be set up to go to the tissues and CO2 to leave the body to be expired.
???
Gas laws
Boyle’s Law: P1V1= P2V2
Dalton’s Law: total pressure exerted by a gas mixture is the sum of pressures exerted by individual gases that make up the mixture
Henry’s Law: amount of gas absorbed by a liquid to which it is not chemically combined is directly proportional to the positive pressure of the gas in the liquid; gives the partial pressure of O2 in the arterial blood
What are the components of the alveolar capillary gas exchange surface?
- liquid layer containing surfactant
- alveolar epithelium
- epithelial basement membrane
- thin interstitial space between alveolar epithelium and the capillary membrane
- capillary basement membrane that fuses with the alveolar epithelial basement membrane
- capillary endothelial membrane
NET diffusion of gases from high to low concentration in the alveolar air depends on what?
on the partial pressure of the gases NOT contraction of any muscle
What forces the oxygen within the air mixture to go into the pulmonary blood?
the partial pressure of oxygen must be higher in the alveolar gas mixture forcing it into the blood of the alveolar capillaries
O2 and CO2 move in_________ directions.
opposite
Oxygen is constantly being absorbed into the pulmonary blood from the alveolar air.
Carbon Dioxide is continuously diffusing from the pulmonary blood into the alveolar air.
O2 has a partial pressure gradient for net diffusion into the blood
Air is conditioned to be taken for gas exchange.
humidifier with water vapor to help condition help before it gets to alveoli
What is the normal barometric pressure? What gas components comprise this pressure?
760 mL mmHg
N2, O2, CO2, H2O
We do not want huge swings in partial pressure of gases. Normally we have FRC at the onset of every inspiratory effort. What prevents huge changes in the blood gases?
only a portion of functional residual capacity is changed over with each breath ????
rate of ven affects how fast or slow the partial pressure of gases in alveolar air will fluctuate
which will affect blood gas subsequently
CO2 is eliminated and O2 brought in to maintain physiological balance pH
????
Why does gas exchange continue even when respiration is temporarily interrupted (apneic pause)?
you have FRC
Functional residual capacity (FRC) is defined, in classical physiology, as the volume of gas remaining in the lungs at the end of expiration. In other words, FRC is the volume at which the elastic recoil pressure of the chest wall equals that of the lung and, at FRC, the system is in equilibrium.
Majority gas in air is?
nitrogen
Water vapor pressure is what? It does not change!!
47 mmHg
Partial pressures for what are denoted by Pa and PA?
Pa= arterial blood PA= alveolar air
How do calculate for the amount of air that participates in gas exchange?????
subtract the dead space (stays in conducting tubes) volume from tidal volume times frequency
What gas is continuously produced by tissues as metabolic waste and eliminated by ventilation?
CO2
What is the relationship between partial pressure of CO2 and ventilation?
they are inversely proportional
What is the progressive changes in partial pressure of O2 in expired air from the conducting zone to the respiratory zone?
conducting zone (dead air space, humidified): 150 mmHg
gradual mixing of dead space with alveolar air
respiratory zone (alveolar air): 100 mmHg
What is the progressive changes in partial pressures of CO2 in expired air from the conducting zone to the respiratory zone?
conducting zone (dead air space, humidified): 0 mmHg
gradual mixing of dead space with alveolar air
respiratory zone (alveolar air): 40 mmHg
For every respiratory cycle you have fresh and stale air. What is the fresh and stale air?
fresh air: the air you breath in
stale: the air remaining after each expiratory effort; does not participate in gas exchange
so with every breathe you are constantly refreshing the stale air in the dead air space
What occurs in the Fowler’s method of dead space measurement?
- Subject takes a single breath of 100% O2 and then exhales into a tube that continuously measures the [N2] in the expired gas.
- Anatomic dead space containing 100% O2 and 0% N2 empties first followed by alveolar emptying.
- Alveolar emptying results is a rise in [N2] and a decline in [O2] until a plateau is reached (indicates alveolar gas only).
- The volume with initially 0% N2 plus 50% of the rising N2 volume is equal to the anatomic dead space.
