transporting oxygen

how is oxygen carried in the blood

1. oxygen exchange at alveoli

2. oxygen transport

3. oxygen exchange at cells

4. carbon dioxide exchange at cells

5. carbon dioxide transport

6. carbon dioxide exchange at alveoli

reversible oxyhaemoglobin equation

1. haemoglobin + oxygen -- Oxyhaemoglbin

2. Hb + 4o2 --- HbO8

partial pressure

measure of the amount of a gas present in a mixture of gases

where is pO2 highest and lowest in the body

• alveoli

• body tissues after being used

describe the structure of haemoglobin

• has 4 haem groups- they have an affinity for oxygen

• is a globular protein

• complex protein consisting of 4 subunits of 2 alpha chains and 2 beta chains

• these each contain a central haem group containing Fe 2+

• oxygen binds to the iron within the haem group

describe and explain the shape of the graph

• sigmodial ( s-shaped) curve results from co-operative binding

• at low pO2 it is difficult for hb to pick up O2

• when one O2 binds to Hb, it distorts the shape of the molecule, making it easier for more o2 to bind

• after 3 o2 have bound to hb, it is very difficult for the 4th to bind. even at high po2, it is difficult for hb to be fully saturated with o2

explain why the curve is different for foetal haemoglobin

• foetal hb has a higher oxygen affinity than adult hb

• because foetal hb needs to be able to pick up oxygen from the mothers blood in the placenta

which direction is the bohr shift

• to the right

why is haemoglobin efficent at transporting oxygen

• it can readily associate with oxygen at gas exchange surfaces

• this will increase po2 in blood

why is haemoglobin again efficient at transporting oxygen

• readily dissociate with oxygen ar the tissues

• this will increase po2 in the tissues and decrease it in the blood

when does hb change its affinity for oxygen

• under different conditions eg

• low ph

• high co2

what does the presence of co2 have on hb

• makes hb associate less readily with o2

• therefore releasing o2 in the presence of high co2 such as tissue

• this is the bohr effect