Part V Flashcards
Define the Starling forces.
an equation that illustrates the role of hydrostatic and oncotic forces in the movement of fluid across the capillary membranes
Capillary hydrostatic pressure - interstitial hydrostatic pressure= ?
filtration forces
plasma colloid osmotic pressure - interstitial colloid osmotic pressure= ?
Reabsorption forces
filtration forces - reabsorption forces= ?
net forces (favor filtration)
Any excess fluid in the pulmonary capillaries or particles we inhale is taken where?
lymphatics
What is vapor pressure of H2O?
pressure that is exerted by the water molecules to escape form the liquid to air
What is vapor pressure due to?
molecular motion and is proportional to temperature
What is the vapor pressure of water at body temperature?
47mmHg
What is body temperature in celcius?
37 degrees celcius
What part of atmospheric air is significantly increased once it hits the alveoli?
CO2
What is the dilution effect?
as water, oxygen and nitrogen are diluted, carbon dioxide is concentrated
What is the alveolar oxygen concentration?
104 mmHg
What is the alveolar carbon dioxide concentration?
40 mmHg
Boyle’s law.
If temperature and volume are constant and there is a given quantity of gas, pressure is inversely proportional to volume
Avogadro’s law.
volume of gas at the same temperature and pressure contain the same amount of molecules
Charles’ Law.
at a constant volume, the pressure of gas is proportional to its absolute temperature.
Grahm’s Law.
the rate of diffusion of gas is inversely proportional to the square root of its molecular weight. (bigger moleculaes are slower to diffuse than smaller molecules)
Henry’s Law.
the quantity of gas that can dissolve in a fluid is equal to the partial pressure of the gas times the solubility coefficient
Dalton’s Law of partial pressures.
the pressure exerted by a mixture of gases is equal to the sum of the individual partial pressure exerted by each gas
What is the dilution coefficient?
solubility/ square root of molecular weight
What are the properties of gas?
solubility proportional, square root of molecular weight is inversely proportional
What does the relative diffusion coefficient represent?
how readily a particular gas will diffuse across the respiratory membrane and is proportional to its solubility and is inversely proportional to the square root of the molecular weight
The lungs consist of how many alveoli?
300 million
What are the two cell layers of the respiratory membrane?
Alveolar epithelium and capillary epithelium
How thick is the average epithelium of the lung?
.5-.6 microns
What is the total surface area of the lung?
50-100 meters squared
How much pulmonary capillary blood is there usually?
60-140mL
What is the normal amount of oxygen in the lung at a time?
21mL/min/mmHg
What is the mean pressure gradient of oxygen?
11mmHg
How fast does oxygen go through the lung?
230mL/min
Does oxygen increase during exercise?
Yes
What diffuses 20x more rapidly than oxygen?
CO2
As you expire a normal tital volume, what happens to oxygen?
Goes from 159 to 104mmHg
As you expire a normal tital volume, what happens to CO2?
0-40mmHg
As you expire a normal tital volume, what is the last 250mL of air?
alveolar air
As you expire a normal tital volume, what kind of air is the middle 150mL of air?
mix of dead space and alveolar air
How many breaths does it take to completely turn over alveolar air?
6-7 breaths
Why does it take so many breaths to completely turn over alveolar air?
it helps prevent large changes in gas concentration in alveoli from breath to breath
What is the normal rate of ventilation-perfusion?
4L/m of air to 5L/m of blood
If the V/P ratio decreases, what is it usually due to?
decreased ventilation
What is the more unlikely reason the V/P ratio could decrease?
too much perfusion
If the V/P ratio increases, what is it usually due to?
decreased perfusion of the lungs or increased ventilation from increased physiologic dead space or wasting ventilation
