23 Jan, 2012 Lecture Notes Physiology II
23 Jan, 2012
How the gas gets from the alveolus to the tissues?
Blood is like a highway system, it’s a way all the nutrients can get into the system ( happens via
Transport of O in2the blood.
3ml is very less ( 1 teaspons is 5ml)
5L ( blood volume) per minute. Blood circulates around your body . (while sitting)
3ml (oxygen) X 5L of blood =15mL of O2 is carried.
Total of 15mL of O is2carried
Atotal of 15mL of O is 2arried dissolved in the blood per minute.
At rest, (not eating) we need about 250ml of oxygen per minute to just SURIVE to do basal
functions ( basic functions, breathe, stay awake, tissues to survive)
-15ml is very less, (not enough ) therefore we need to make up the 235ml/min O2 difference.
-Protein in our red blood cells “Haemoglobin” is made of 4 globin subunits that contain 4
heme groups.. hence the name haemoglobin
-Each one of the heme molecules contains an iron molecule that can bind oxygen..
-Every 4 heme group can can carry 4 oxygen molecules. Each carries 1 oxygen.
-Heme have redish colour hence that’s why they are called red blood cells since they are filled
with haemoglobin ( tastes like iron if u taste blood)
-Iron holds the oxygen that’s why we need it
-Hemoglobin ( if nothing is bound to it ) its called deoxy Hemoglobin
-Hemoglobin (if oxygen is is bound it ) its called oxyHemoglobin 23 Jan, 2012 Lecture Notes Physiology II
-How does Hemoglobin help us out?
-Every gram of haemoglobin binds about 1.4 ml of oxygen and the concentration of Hb is
15g/100ml of blood.
Heart pumps= 5 L of blood or 5000ml every minute
We only need 250 ml O2/min .. We have 800ml O extra2in case we need extra.
Haemoglobin allows us to carry more than enough OXYGEN per liter of blood/min
It allows the amount of oxygen pressure in the blood to STAY LOW.
(REFER TO THE ADDITIONALSLIDE)
The movement of oxygen and carbon dioxide ((or any gas) is dependent on pressure. It’s about
~105-110mmHg for oxygen into the alveoli.
Driving pressure needs to be higher in alveoli than the blood in order to get it in the BLOOD.
-Oxygen is in the form of dissolved oxygen that tells us wat the partial pressure of oxygen is in
-Stuff bound to haemoglobin does not exert any pressure.
-Blood is broken down into plasma and red blood cells.
-Dissolved oxygen would reach 100mmHg very quickly and at small volume
-In order to keep the dissolved oxygen in the red blood cells (erythrocytes) and plasma LOW
and we do that by leaving it dissolved its picked up by haemoglobin.
-Once all the haemoglobin is full we build up that extra oxygen it builds up pressure of 100
mmHg and gas movement stops.
Cookies are held in a jar, if the person that fills that cookie jar stop once they are full.
Once friends were over, mom would keep making cookies and all friends would take a handful
but the jar will be half full. Cookies will still be made, until and unless everyone is full and
nobody is taking more. (SAME AS HAEMOGLOBIN) 23 Jan, 2012 Lecture Notes Physiology II
-Cookie jar= oxygen dissolved in the blood and it doesn’t hold that much oxygen
-Haemoglobin= keeps taking oxygen out of the dissolved portion which allows us to keep
brining oxygen in.(it keeps the pressure low, lower in the alveolus which allow is to drive it )
-Once the haemoglobin is full the dissolved oxygen builds up in the blood and that stops the
movement of oxygen back into our system.
How Hb Increases O Tra2sport
1. Each side has 6 molecules of O2. Pressure is at equilibrium (sim to lungs)
2. Now the haemoglobin molecule has been dumped in which will pick 4 molecules of oxyg