Oxygen Carrying Capacity

When oxygen diffuses into our blood it combines chemically with hemoglobin When oxygen diffuses into our blood it combines chemically with hemoglobin Hemoglobin: (Hb) Hemoglobin: (Hb) a special globular protein with and embedded heme component (iron) a special globular protein with and embedded heme component (iron) Found in red blood cells Found in red blood cells When combined with O 2 it forms “oxyhemoglobin” When combined with O 2 it forms “oxyhemoglobin” Each hemoglobin molecule carries 4 O 2 molecules Each hemoglobin molecule carries 4 O 2 molecules

At rest, under normal conditions: At rest, under normal conditions: 1 gram of Hb can hold 1.39 ml/g of oxygen 1 gram of Hb can hold 1.39 ml/g of oxygen So in 100 ml of blood you can hold So in 100 ml of blood you can hold 15g/100ml X 1.39 ml/g of oxygen = ml of oxygen/100 ml of blood

The greater number of hemoglobin you have, the greater amount of oxygen you carry The greater number of hemoglobin you have, the greater amount of oxygen you carry The amount of hemoglobin is a fixed amount that varies little between individuals The amount of hemoglobin is a fixed amount that varies little between individuals On average: On average: Adult males: g/100 ml Adult males: g/100 ml Adult women: g/100 ml Adult women: g/100 ml

During Exercise Your HB concentration rises But hold on a second, you just said Hb concentration was a fixed amount But hold on a second, you just said Hb concentration was a fixed amount You have to ask yourself, You have to ask yourself, “ Hey self, how in the world, can we add Hb to our blood during exercise? “ Hey self, how in the world, can we add Hb to our blood during exercise? I didn’t say we added Hb I didn’t say we added Hb I said the concentration rose. I said the concentration rose.

To understand this we must know the composition of blood To understand this we must know the composition of blood Blood is made up of solids and liquid Blood is made up of solids and liquid The liquid portion of blood which makes up about 55% of blood, is called PLASMA The liquid portion of blood which makes up about 55% of blood, is called PLASMA The solids in blood make up about 45% of blood The solids in blood make up about 45% of blood

The solids are made up of Red Blood cells, White Blood cells and Platelets The solids are made up of Red Blood cells, White Blood cells and Platelets

How in the world can the concentration of Hb rise during exercise? During exercise some of the fluid portion of the blood shifts in the muscle (causing it to swell) During exercise some of the fluid portion of the blood shifts in the muscle (causing it to swell) This leaves the same number of RBC’s in a lesser liquid This leaves the same number of RBC’s in a lesser liquid Therefore a higher CONCENTRATION of Hb in the blood Therefore a higher CONCENTRATION of Hb in the blood

During exercise the Hb concentration rises as high as 20.1 g/100 ml of blood During exercise the Hb concentration rises as high as 20.1 g/100 ml of blood So So 20.1 X 1.39 ml/g 20.1 X 1.39 ml/g = ml/g (up from ml at rest) Not a huge growth but helps carry more oxygen

HB Saturation All the preceding information is only true if each Hb molecule hold 4 oxygen molecules All the preceding information is only true if each Hb molecule hold 4 oxygen moleculesOr Is completely SATURATED with oxygen To find out if this is true use……….. THE OXYHEMOGLOBIN DISASSOCIATION CURVE

The curve relates Partial pressure of oxygen with the % saturation of hemoglobin with oxygen The curve relates Partial pressure of oxygen with the % saturation of hemoglobin with oxygen At what PO 2 is our HB 100% saturated? At what PO 2 is our HB 100% saturated? At 100mmHg At 100mmHg Why is this an important number? Why is this an important number? When is our HB fully saturated? When is our HB fully saturated?

AllTheTime The partial pressure in our alveoli is ALWAYS 100mmHg

When is the only time our Hb would not be full (fully saturated)? When the partial pressure of oxygen is greater or less than 100mm Hg When the partial pressure of oxygen is greater or less than 100mm Hg At Altitude or under water At Altitude or under water

Our blood (or more specifically) our Hb is always full and cannot take any more Our blood (or more specifically) our Hb is always full and cannot take any more We do not “run out of oxygen” when we exercise We do not “run out of oxygen” when we exercise We are full and cannot carry any more We are full and cannot carry any more

So…. What if we breath pure 100 % Oxygen, can carry more O 2 ? NO According to the Hb disassociation curve at 100mmHg our Hb is 100% saturated (there are other minor benefits but NONE to oxygen carrying capacity) you will read about them in your text page 132 Make notes on the controversy over hyperbaric oxygen therapy and oxygen bars.