Gaseous exchange

Question 1

What happens during gaseous exchange

Answer 1

• Delivering O2 to Muscles
• Removing CO2 from muscles
• At the lungs O2 enters blood and CO2 leaves blood, At muscles O2 enters and CO2 leaves

Question 2

What happens during diffusion

Answer 2

• O2 and CO2 move by the process of diffusion
• Diffusion - Gases move from high concentration to low.
• The concentration is measured as partial pressure and is represented by a symbol ‘p’ before the gas.

Question 3

Gaseous exchange in the lungs

Answer 3

Inhaled air travels to alveoli where diffusion takes place.

Question 4

What makes diffusion at lungs effective

Answer 4

• Thin walls between alveoli and blood vessels - Short distance
• Thin capillaries, 1 blood cell at a time, slow travel
• Dense capillary network, covers alveoli
• Layers of moisture on wall of alveoli aids diffusion.
• So many alveoli, huge surface area.

Question 5

Gaseous exchange at muscles

Answer 5

• Diffusion occurs at the muscles, opposite way round from lungs.
• O2 moves out the blood into the muscles, lower PO2 in muscles.
• CO2 moves out the muscles in to the blood, Lower PCO2 in blood.