Exchange surfaces

Question 1

3 factors that effect need for transport system

Answer 1

-size
-SA:vol
-level of activity

Question 2

SA:vol

Answer 2

-small organisms have large SA:vol
-large organisms have small SA:vol, so diffusion of oxygen wouldn’t reach innermost cells- exchange system needed
- SA/vol

Question 3

Features of good exchange system

Answer 3

-large SA eg. cristae in mitochondria
-thin permeable walls for short diffusion pathway eg. alveoli walls
-good blood supply maintains concentration gradient

Question 4

Ventilation

Answer 4

-refreshing of air in the lungs so there’s a higher concentration of oxygen than in the blood and lower CO2 concentration

Question 5

Inspiration

Answer 5

-diaphragm contracts + moves down pushing organs down
-external intercostal muscles moves ribs up, increasing vol
-pressure inside lungs drops below atmospheric pressure
-air enters lungs

Question 6

Expiration

Answer 6

-diaphragm relaxes and pushes up
-intercostal muscles relax and ribs fall, volume decreases
-pressure inside chest cavity increases
-air exits the lungs