Lung Structure and Breathing

Question 1

Trachea

Answer 1

Tube through which air passes to the lungs, via the bronchi(oles).

Question 2

Bronchi, Bronchioles

Answer 2

1. The major air passages leading from the trachea to the lungs.
2. The smaller branches into which the bronchi divide.

Question 3

Alveoli

Answer 3

The minute air sacs (connected to the bronchioles) within the lungs that allow for rapid gas exchange.

Question 4

Diaphragm

Answer 4

A thin muscle that sits at the base of the chest, separating the abdomen from the chest.

Question 5

Ribs

Answer 5

A group of long, curved bones that form the rib cage, protecting the lungs and heart from damage.

Question 6

Intercostal muscles

Answer 6

Groups of muscles that run between the ribs and aid in breathing.

Question 7

Pleural membranes

Answer 7

Two thin, moist membranes which separate the lungs from the rest of the thorax.

Question 8

Inspiration / breathing in

Answer 8

• The diaphragm contracts and moves downwards.
• The intercostal muscles contract, moving the ribs upwards and outwards.
• This increases the volume of the chest and decreases the internal air pressure - sucking air into the lungs.

Question 9

Expiration / breathing out

Answer 9

• The diaphragm relaxes and moves back to its domed shape.
• The intercostal muscles relax, moving the ribs inwards and downwards.
• This decreases the volume of the chest and increases the internal air pressure - forcing air out of the lungs.

Question 10

Investigating breathing in humans

Answer 10

• Half-fill a test tube with limewater.
• Place a rubber bung with a hole in it over the test tube, and attach this to a mouthpiece.
• Gently breathe in and out into the mouthpiece. You should observe the limewater becoming cloudy and bubbly.