Gaseous Exchange and transport of O2 and CO2

Question 1

Gaseous exchange

Answer 1

The movement of oxygen from the air into the blood and carbon dioxide from the blood into the air.

Question 2

Law of partial pressures

Answer 2

Parcial pressure is the pressure exerted by an individual has that exists within a mixture of gasses.

Gas molecules always diffuse down a concentration gradient (high to low)

Question 3

Gaseous exchange at alveoli (oxygen)

Answer 3

Partial pressure of oxygen is higher in alveoli than in capillaries surrounding alveoli.

Partial pressure of oxygen in blood is lower. So oxygen diffuses from alveoli into blood until pressure is equal.

Question 4

Gaseous exchange at the alveoli (carbon dioxide)

Answer 4

Reverse of oxygen

Partial pressure of carbon dioxide in blood is higher than in alveoli so CO2 diffuses from capillaries to alveoli until pressure is equal.

Question 5

Pulmonary diffusion works well because:

Answer 5

Big surface area to maximise diffusion

One cell thick - only short distance for gases to travel

Good blood supply - alveoli are covered in a network of capillaries- also the diameter of capillaries are less than a RBC so they must travel single file- maximising exposure to oxygen.

Question 6

Gaseous exchange at muscles (oxygen)

Answer 6

Partial pressure of oxygen must be lower at the muscle than in the blood for diffusion to occur.

Lower partial pressure of oxygen allows oxygen to diffuse from blood to muscle until equilibrium is reached.

Question 7

Gaseous exchange at muscles (CO2)

Answer 7

The partial pressure of CO2 must be lower in the blood than the muscle so it diffuses from muscle into the blood to be transported to the lungs.

Question 8

What is the carrier of oxygen

Answer 8

Haemoglobin

Question 9

O2 + haemoglobin

Answer 9

Oxyhaemoglobin

Question 10

How is o2 transported in the blood

Answer 10

97% of o2 in blood combines with haemoglobin to form oxyhaemoglobin

3% dissolved into plasma

Question 11

Muscles oxygen carrier is

Answer 11

Myoglobin

Question 12

Myoglobin has …

Answer 12

A higher affinity for oxygen than haemoglobin.

Question 13

How is carbon dioxide transported (lungs to muscle)

Answer 13

7% dissolves into plasma

23% combines with haemoglobin (carbaminohaemoglobin)

70% is transported as bicarbonate ions (hydrogen carbonate ions)

Question 14

CO2 + haemoglobin =

Answer 14

Carbaminohaemoglobin

Question 15

CO2 diffused in blood

Answer 15

It enters into RBCs and combines with water to form carbonic acid which splits into hydrogen carbonate and hydrogen ions.

The excess hydrogen ions are buffered by the haemoglobin to stop blood becoming too acidic.