The Mechanism of Breathing

Question 1

How is a the diffusion of gases across the alveolar epithelium maintained?

Answer 1

By moving air constantly in and out of the lungs in the process of breathing (ventilation)

Question 2

When is air forced into the lungs?

Answer 2

When air pressure inside the lungs is less than the air pressure of the atmosphere

Question 3

When is air forced out of the lungs?

Answer 3

When air pressure inside the lungs is more than the air pressure of the atmosphere

Question 4

What is inspiration?

Answer 4

Inhalation

Question 5

What is expiration?

Answer 5

Exhalation

Question 6

Where is air forced in inspiration?

Answer 6

Into the lungs

Question 7

Where is air forced in expiration?

Answer 7

Out of the lungs

Question 8

What are the three muscles that act upon the air pressure in the lungs?

Answer 8

• the diaphragm
• the internal intercostal muscles
• the external intercostal muscles

Question 9

What is the diaphragm?

Answer 9

A sheet of muscle that separates the thorax from the abdomen

Question 10

Where do intercostal muscles lie?

Answer 10

Between the ribs

Question 11

What does the contraction of the internal intercostal muscles lead to?

Answer 11

Expiration

Question 12

What does the contraction of the external intercostal muscles lead to?

Answer 12

Inspiration

Question 13

What is breathing in?

Answer 13

An active process

Question 14

What happens to the intercostal muscles in inspiration?

Answer 14

External intercostal muscles contract and internal intercostal muscles relax

Question 15

What happens to the ribs in inspiration?

Answer 15

The are pulled upwards and outwards (increasing thorax volume)

Question 16

What happens to the diaphragm in inspiration?

Answer 16

It contracts causing it to flatten (increasing thorax volume)

Question 17

What happens to the thorax in inspiration?

Answer 17

Increases in volume

Question 18

What happens to lung pressure in inspiration?

Answer 18

Reduces

Question 19

What is the relationship between pulmonary pressure and atmospheric pressure in inspiration?

Answer 19

Atmospheric pressure is greater than pulmonary pressure

Question 20

Where is air forced in inspiration?

Answer 20

Into the lungs

Question 21

What is breathing out?

Answer 21

A passive process

Question 22

What happens to intercostal muscles in expiration?

Answer 22

Internal intercostal muscles contract and external intercostal muscles relax

Question 23

What happens to the ribs in expiration?

Answer 23

The ribs move downwards and inwards (decreasing thorax volume)

Question 24

What happens to the diaphragm in expiration?

Answer 24

They relax so it is pushed up by the contents of the abdomen that were compressed during inspiration (further decreasing thorax volume)

Question 25

What happens to the thorax in expiration?

Answer 25

Volume decreases

Question 26

What happens to lung pressure in expiration?

Answer 26

Increases

Question 27

What is the relationship between pulmonary pressure and atmospheric pressure in expiration?

Answer 27

Pulmonary pressure is grater than atmospheric pressure

Question 28

Where is air forced in expiration?

Answer 28

Out of the lungs

Question 29

During normal breathing, what is the main cause of air being forced out of the lungs?

Answer 29

the recoil of the elastic tissue in the lungs

Question 30

What is the pulmonary ventilation rate equation?

Answer 30

Pulmonary ventilation rate = tidal volume x breathing rate

Question 31

What is tidal volume?

Answer 31

The volume of air taken in at each breath when the body is at rest (usually 0.5)

Question 32

What is breathing rate (ventilation rate))

Answer 32

The number of breaths taken in 1 minute