Mechanics of Breathing

Question 1

pulmonary ventilation

Answer 1

process by which air is transported into and out of the lungs, it has two phases

Question 2

What happens during the first stage of inspiration?

Answer 2

• the external intercostal muscles contract to lift the ribs outwards and upwards
• the diaphragm is forced downwards

Question 3

Inspiration at rest

Answer 3

• the air into the lungs
• the external intercostal muscles contract to lift the ribs outwards and upwards
• the diaphragm is forced downwards
• this causes a drop of pressure within the lungs to below atmospheric pressure
  
  • encourages air to be drawn into the lungs

Question 4

Inspiration during exercise

Answer 4

the contractions are more forceful

Question 5

Expiration at rest

Answer 5

• external intercostal muscles relax
• the diaphragm relaxes, moving upwards, and the ribs move downwards and inwards
• pressure within the lungs increases forcing the air out

Question 6

Expiration during exercise

Answer 6

• external intercostal muscles relax
• the diaphragm relaxes, moving upwards, and the ribs move downwards and inwards
• pressure within the lungs increases forcing the air out
• internal intercostal muscles are also recruited to actively pull the rib cage down - reducing the size of the thoracic cavity