Gas exchange

Question 1

Sites for gaseous exchange

Answer 1

1. between the alveoli of the lungs and the blood surrounding alveolar capillaries (external inspiration)
2. between the muscles/tissues of the body and the surround blood capillaries (internal respiration)

Question 2

Partial pressure

Answer 2

pressure that is exerted by an individual gas when it exists within a mixture of gases.
- gases move from high pressure to low pressure.

Question 3

Why does diffusion take place (external respiration)

Answer 3

• within the alveoli, as you breathe in there is a higher concentration of O2 and lower concentration of CO2.
• diffusion therefore takes place moving o2 from the alveoli into the bloodstream and co2 from the bloodstream to the lungs to be breathed out.

Question 4

Diffusion

Answer 4

movement of gases from a high partial pressure to a low partial pressure until equilibrium is reached.
- the difference in high and low pressure creates a pressure gradient.
- the larger the gradient the faster rate of diffusion

Question 5

Gaseous exchange during exercise - External respiration

Answer 5

• blood returning to the lungs is high in carbon dioxide and low in oxygen therefore the gradient STEEPENS.
• this means carbon dioxide diffuses faster from the CAPILLARY to the ALVEOLI and oxygen in the opposite direction.

Question 6

Gaseous exchange during exercise - Internal respiration

Answer 6

• muscles continually contract and use ready storage of oxygen in the muscles.
• produce higher levels of carbon dioxide and the gradient STEEPENS.
• this means that oxygen diffuses faster from the CAPILLARY into the MUSCLE and carbon dioxide the opposite way.