20 Jan, 2012
Pressure of gas determines where it moves (in or out of the lungs/blood)
79% Nitrogen (inspiration)
79% Nitrogen (expiration) meaning we don’t take any nitrogen
Oxygen rates are dropped, because we take in the oxygen, even the air we breath out
-Carbon dioxide rates are dropped too
-Driving pressure of oxygen is 130.95 that’s above the 40 to 60 that’s in our venous blood.
-The air that comes into our lungs has partial pressure of 40, even if you don’t breath again you
still have 130.95 ( lots of oxygen) driving pressure in alveolus and only 40 pushing back in the
vein/capillary . (oxygen can still go in) this is why you can hold ur breath because when you do
that oxygen is still there.
-When you hold your breath, O is 2till there and we can use that O until2the driving pressure
goes to a level until that driving pressure of oxygen is less than or equal to what’s in the veins
(then you can’t bring any more in)
*We don’t use all of our oxygen when we breath
-CO2 goes from 0.23mmHg to 28.12mmHg (a lot of Co2) all the Co2 we produced by exercise
by metabolism ,exercise. All these pressure differences in alveoli & blood drive gas movement.
-Blood and tissue changes also determine gas movement at the tissue
Gasses Dissolved in Liquids
Henry’s Law tells us how we can tell how much gas is in any given liquid.
ml/dl = millimetres/decilitres
k = always same
increasing pressure = increasing concentration ;decreasing pressure =decreasing concentration
* directly proportional
K is diff for different gases Oxygen has (mid-level K) ; we can dissolve a little bit of oxygen but not a lot.
Nitrogen (very low K); we cannot push much nitrogen into a liquid that’s why when we breath in
and out we don’t take it on nitrogen because the pressure is not enough to push in.
-In depth pressure increases
-If a scuba diver dives deep in water and they breath air not O2, pressure is above 760mmHg.
Eventually there is a point where you start to take nitrogen into the blood. You don’t come right
way back up because otherwise the nitrogen will start to bubble in your system .. The nitrogen
will start to bubble out of the tissues (bends) .
-Coming up to fast; nitrogen can block arteries to brain, but mostly causes JOINT pain, since
there is gas in joints.
-Understand the diagram ( for test)
-Partial pressure of O2 was 160mmHg.
-When you breath out, you don’t get rid of all the air; (150 dead space); there is air in residual
volume and alveoli filled with air, and only a little bit fresh air moves in.
-When the fresh air mixes with the air that’s still in the lungs the actual partial pressure of O2
goes down since the percentage of oxygen is less than the air.
-Taking something with a lot of oxygen and mixing with air which has less oxygen.
-The 350ml that we breathe in
-The partial pressure goes from 160 to 100. The actual partial pressure of O in a2veolus is 100.
-So in order to get O2 in the blood, the pressure in the blood has to be less than 100( <100)
-CO2 is 0.23 ;
-When fresh air is mixed with air in the lungs, it has a much higher CO2 ( thereforeCO2 about
40 in our alveolus)
- Therefore in order to get Co2 from theblood from the alvelos the pressure has to be
greater than 40 otherwise it would not be pushed out.
-Oxygen (PaO ) 2mall a = arterial it’s also a 100 , which is the same as the PA.. If you decrease
in alveolus (PA) it will also drop the Pa too.
-Co2 and oxygen reach equilibrium at the lung.
-In the veins coming from the tissues we have partial pressure of O2 =40mmHg
-PvO =2Pressure of oxygen in the veins and its 40 -40 in the veins that gets to capillaries , 100 is greater than 40 therOxygen is pushed
into the capillaries from the alveolus until it reachs 100 ; comes to equilibrium gas stops moving.
(same as bulk flow)
-Carbon dioxide from the tissue is 46mmHg; that’s higher than 40mmHg in the alveoli that
means CO w2ll be pushed from the blood into the alveoli till it reaches 40mmHg (equilibrium).
-Arterial blood now got rid of CO2and has oxygen which takes it to the tissues.
-Blood travels back to the heart down to the tissue. The partial pressure of oxygen in the tissue is
less than 40mmHg ( <40) . SO the oxygen gets starts to pushed since its 100mmHg in the
capillary and its gets pushed into the tissue until it gets 40mmHg.
-Carbohydrates, proteins, fats combine those with oxygen which creates ENERGY.
-We use oxygen because it gives us a lot of energy
-Carbon dioxide starts to build up in the tissue when producingATP, which is greater than
46mmHg (> 46); CO2 goes from the tissue (where the pressure is high) to the blood (where the
pressure is low 40mmHg).
-Pick up CO from the tissue dump of at lung