B2: THE LUNGS

Question 1

What are the functions of the lungs?

Answer 1

-gas exchange
-ventilation

Question 2

What happens when you breathe in/inhale?

Answer 2

-ribcage moves upwards and outwards as the lungs expand and the intercostal muscles contract
-diaphragm contracts and flattens (moves downwards)
-volume of chest increases
-air pulled in

Question 3

What happens when you breathe out/exhale?

Answer 3

-rib cage moves downwards and inwards as lungs decrease in volume and intercostal muscles relax
-diaphragm relaxes and curves upwards
-volume of chest decreases
-air pushed out (higher air pressure)

Question 4

In what part of the lungs does gas exchange occur?

Answer 4

alveoli

Question 5

Describe the process of gas exchange

Answer 5

-the blood in the capillaries surrounding the alveoli contains a high conc of CO2 and a low conc of O2
-O2 diffuses from the alveoli into the blood and CO2 diffuses into the alveoli from the blood to be breathed out
-when the blood reaches body cells, O2 diffuses from the blood into the cells for respiration and CO2 from the cells diffuses out of the cells, into the blood to be carried back to the lungs