1. Internal Respiration

2. Warm Up 1 In pairs chose either inspiration or expiration.
You have one minute each to describe your chosen process.
You must explain….
Pressures of air in lungs and outside of body
Which type of intercostals used
How this changes when you exercise

3. Warm Up 2 A sticker will be placed on your back
You have 5 questions to guess what you are.
The person you are asking can only answer ‘yes’ or ‘no’
The topic is ‘Lung Volumes’

4. Internal Respiration
Pulmonary diffusion is the process used to explain the process of gaseous exchange in the lungs- it has 2 functions
Replenish blood with oxygen- can then be taken to tissues an muscles
Remove carbon dioxide form the blood which has resulted from metabolic processes.

5. Partial Pressure of Gases
The individual pressure that the gas exerts when it occurs in a mixture of gases
The gas will exert a pressure proportional to its concentration within a whole gas.
Partial pressures of each gas adds up to the total pressure of the gas

6. Air
Nitrogen 79%
Oxygen 20.9%
CO %
Total atmospheric pressure at sea level is 769mmHg

7. Partial Pressure of Oxygen
Concentration of O2 is 21% and nitrogen is 79% together they exert a pressure of 760mmHg
pO2 Can be calculated as follows;
= Barometric pressure x fractional concentration
= 760 x 0.21
= mmHg
The partial pressure of a gas explains the movement of gases within the body

8. ????
Work out the partial pressure of nitrogen

9. Gaseous Exchange at the Lungs
The imbalances of gases at the alveoli and the blood that causes a pressure gradient which results in a movement of gases across the membrane.
It is a 2-way movement with oxygen moving from the alveoli to the blood and CO2 moving from the blood to the alveoli

11. Gaseous Exchange at the Lungs
Partial pressure of O2 in the atmosphere is 159mmHg
This drops to 105mmHg in the alveoli
The diffusion gradient
Blood in the pulmonary arteries has a pO2 of 45mmHg as most of the O2 has been used by the working muscles

12. The diffusion gradient
This makes a pressure gradient of approx 60mmHg
(pO2 of 105mmHg in the alveoli)
This forces the oxygen to move from the alveoli to the blood until pressure is equal on both sides.
High- Low

13. The diffusion gradient
In the same way, CO2 moves from the pulmonary capillaries to alveoli
There is a pCO2 of 45mmHg in the blood returning to the lungs and pCO2 of 40 mmHg in the alveoli
This is a small pressure gradient 5mmHg
CO2 can diffuse a lot quicker than O2.

14. Endurance Athletes
Endurance athletes with larger aerobic capacities will have greater oxygen diffusion ability as a result of increased cardiac output, and resistance to diffusion.

15. Gaseous Exchange at the Muscles
pO2 in blood of 100mmHg and a low pO2 in muscle of 40mmHg causes a diffusion gradient.
High to Low
pCO2 of 40mmHg in blood and 46mmHg in muscle causes a small pressure gradient

16. Oxygen dissociates from haemoglobin to travel into the muscle.
Once it is on the cell it attaches to myoglobin which takes it to the mitochondria where aerobic respiration can take place
Myoglobin has a higher affinity for O2 than haemoglobin and acts like an oxygen reserve so when we need more oxygen
i.e. in exercise, there is a readily available source.

17. In Exercise
The production of carbon dioxide stimulates the dissociation of oxygen from haemoglobin, and this together with greater tissue demand for oxygen increases the pressure gradients during exercise.

18. Exam Questions Explain how gaseous exchange occurs in the lungs
(3 marks)
Explain how gaseous exchange occurs in the muscle tissue
Explain how this process changes during exercise