Lecture 3 Resp (Principles of gas exchange) Flashcards
co2 and o2 are exchanged by what transport
simple diffusion
c02 and 02 diffusion are driven by what energy of each individual molecule
kinetic energy
what is the most important parameter in gas exchange
the rate of diffusion
total pressure of a chamber of gasses is directly proportional to what?
The concentration of all molecules
Pressure exerted by all molecules of the certain type is called the…
Partial pressure
what is the composition of o2 in the atmosphere
21% (160mmhg)
what is the composition of nitrogen in the atmosphere
79% (500mmhg)
carbon dioxide dissolves rapidly or slowly?
rapidly
when co2 and h20 combine to form carboxylic acid slowly through carbonic anhydrase, do they still contribute to partial pressures
no
what is henry’s law
pressure = concentration/solubility (a gas in liquid phase)
diffusion rate “D” is driven by the differences in what?
partial pressure differences
higher solubility increases or decreases diffusion rate
increases (they travel in fluid form)
increase cross sectional area increases or decreases diffusion rate
increases
decreased distance gases must travel increase or decrease diffusion rate
increase
increases molecular weight increases or decreases diffusion rate
decreases
because o2 diffusion coefficient is 1, and co2 is 20.3, this means that co2 does what
diffuses faster and better
what is the main dissolving media for gasses in live tissues
water
Are pulmonary capillaries endothelial lined or epithelial?
Endothelial
Are alveoli capillaries endo or epithelial lined?
Epithelial
Can transpulmonary gasses go from both high to low, and LOW to HIGH concentration?
yes (but net filtration is always from high to low)
The pressure that water molecules exert upon escaping is called?
Vapor pressure
What is normally thte phase of water at body temperature?
Gas phase (insensible loss because water wants to vaporize, and can do so in the alveoli)
In a single respiration, what is the MOST transported molecule across the pulmonary membrane?
- o2
- Co2
- Water
- Water (a difference of 47%)
(02 is 7%, co2 is 40%)
see slide 10.
What percentage of tidal volume versus total lung volume during quiet respiration is actually participating in gas exchange?
15%
lung volume: 2300ml, tidal average 350ml
What is the reason alveolar air upon inspiration contains 40mmg of co2, then upon exhale it is only 27mmhg?
Because the air in the dead space reflects atmospheric air, which when mixed during expiration, changes the average value of all those gasses to resemble something closer to atmospheric condition.
what alveolar substance does not change in concentration (partial pressure) when mixed with dead space?
Water
what is the mechanism by which we attempt to compensate for the bodies increased demand in oxygen?
Breathing
What decreases partial pressure of alveoli?
increased absorption (metabolic demand)
What increases the partial pressure of 02 in alveoli?
Increased breathing
What are the 4 structures of the “Respiratory Unit”
Respiratory Bronchiole
Alveolar Ducts
Atria
Alveoli
What layer of the respiratory membrane is thickened during pulmonary edema?
The interstitial layer
What is the pressure in the interstitium between the respiratory membranes?
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