Describe the function of the alveoli

Question 1

The pathway of air

Question 2

step 1)

Answer 2

Air is taken in through the mouth or nose.

Question 3

step 2)

Answer 3

The air flows through the trachea (windpipe).

Question 4

step 3)

Answer 4

When the trachea reaches the lungs, it divides into 2 branches called the bronchi. Each of these bronchi enters a lung

Question 5

step 4)

Answer 5

In the lungs, the bronchi divide further into many bronchioles. These bronchioles are less than 1 mm in diameter.

Question 6

step 5)

Answer 6

At the end of the bronchioles are a cluster of alveoli. These are tiny air sacs where gaseous exchange takes place.

Question 7

Adaptations of the Lungs for Gaseous Exchange

Question 8

Contain alveoli

Answer 8

There are millions of alveoli (air sacs) in each lung (approximately 150 million in each).
The alveoli have the following adaptations for gaseous exchange:
They are only 1 cell thick, meaning that there’s a short distance for the oxygen to travel.
They are moist.

Question 9

Good blood supply

Answer 9

There is a very good blood supply to the lungs. This means that there are plenty of capillaries (blood vessels) surrounding the alveoli for diffusion to take place.

Question 10

Large surface area

Answer 10

Because each bronchiole contains a cluster of alveoli, there is a large surface area for diffusion to happen over. This lets the blood absorb more oxygen.
The capillaries are only 1 cell thick and wrap tightly around the alveoli, so the distance for diffusion remains small.

Question 11

Gaseous exchange in the lungs

Answer 11

For diffusion to happen, there must be a difference in the concentration of a gas in the alveoli and in the blood. The gas will diffuse from the area of higher concentration (more particles) to the area of lower concentration (less particles).

Question 12

Oxygen

Answer 12

Oxygen travels from the alveoli into the blood because:
There is a high concentration of oxygen in the alveoli.
There is a low concentration of oxygen in the blood.

Question 13

Carbon dioxide

Answer 13

Carbon dioxide travels from the blood into the alveoli because:
There is a high concentration of carbon dioxide in the blood.
There is a low concentration of carbon dioxide in the alveoli.

Question 14

Haemoglobin

Answer 14

Red blood cells carry haemoglobin, which transports gases around the body.
Haemoglobin carries carbon dioxide from the body to the alveoli in the lungs.
Oxygen binds with haemoglobin to make oxyhaemoglobin. This is transported through the blood to the tissues around the body.