8a – Efficient transport and exchange

Question 1

exchange surface

Answer 1

a specialized area that is adapted to make it easier for molecules to cross from one side to the other

Question 2

adaptations of an exchange surface

Answer 2

• Are thin, so particles don’t have to diffuse far (short diffusion pathway)
• Have a large surface area, so there is more room for more particles to diffuse, increasing SA: V ratio, and thereby increasing speed of gas exchange.
• Well ventilated, so there is higher concentration gradient.

Question 3

gas exchange in the alveoli

Answer 3

• Deoxygenated RBC’s with a high concentration of CO2 and low concentration of oxygen flows through capillaries next to an alveoli.
• Since there is a higher concentration of oxygen in the alveoli than in the RBC, diffusion occurs and oxygen flows into the RBC’s.
• The opposite occurs for CO2 as there is a lower concertation of CO2 in the alveoli. The RBC’s leave to the rest of the body, now oxygenated.