Gas Laws in the Respiratory System - Boyle's Law

Question 1

During inspiration, what happens to the diaphragm? (2)

Answer 1

It contracts and becomes flatter/ less dome-like

creating a vacuum, thus pulling air into the lungs

Question 2

During expiration, what happens to the diaphragm? (2)

Answer 2

The smooth muscle of the diaphragm relaxes, and become very dome-shaped/domed
(thus forcing air out of the lungs)

Question 3

During inspiration, does the volume of the lungs increase or decrease?

Answer 3

Increase

Question 4

What happens to the volume of the lungs during expiration

Answer 4

The volume of the lungs DECREASES

Question 5

When does contraction (shortening) of the intercostal muscles take place?

Answer 5

During inspiration

Question 6

What do the intercostal muscles do during expiration?

Answer 6

They relax (e.g. expand)

Question 7

What is the primary function of the muscles that make up the thoracic cage?

Answer 7

They act to change the VOLUME of the thoracic cavity during respiration

Question 8

What does relaxation of the intercostal muscles do to the ribs? (2)

Answer 8

Ribs move downwards and inwards

during expiration

Question 9

The ribs move upwards and outwards when the intercostal muscles are doing what?

Answer 9

Contracting/shortening/’shrinking’

during inspiration

Question 10

What two combined, mainly involuntary* actions increase the volume of the size of the lungs? (2)

Answer 10

Contraction of the diaphragm 
smooth muscle (which flattens its shape)

Contraction of the intercostal muscles (causing ribs to move up and out)* [these muscles can be controlled by voluntary mechanisms also]

Question 11

Relaxation of both the diaphragm, and the intercostal muscles does what to the volume of the size of the lungs?

Answer 11

Decreases the volume of the size of the lungs

Question 12

Decreased lung size/volume means the pressure inside the lungs is greater/higher than the atmosphere outside the lungs. What happen to air, and what is this breathing called? (2)

Answer 12

Air moves out of the lungs
(high pressure to low pressure thus expelling waste CO2)

This is called expiration or exhalation

Question 13

In order for air to move into the lungs, the pressure inside the lungs must be what in comparison to the air in in the atmosphere outside the lungs?

Answer 13

Lower/decreased

gases move from high pressure to low pressure

Question 14

What happens to the alveoli during expiration?

Answer 14

They deflate

Question 15

During inspiration, what structures inside the lungs inflate?

Answer 15

Alveoli