Mechanism Of Expiration/Exhalation

Question 1

Step 1 Of Expiration

Answer 1

Internal intercostal muscles contract, external intercostal muscles relax.

Question 2

Step 2 Of Expiration

Answer 2

Ribs move downwards an I wards decreasing the volume in the thorax.

Question 3

Step 3 Of Expiration

Answer 3

Diaphragm muscle relaxes, causing it to move upwards to its domed position decreasing the volume in the thorax.

Question 4

Step 4 Of Expiration

Answer 4

Decrease in volume of the thorax cause an increase in the pressure inside the lungs.

Question 5

Step 5 Of Expiration

Answer 5

Atmospheric pressure (air pressure outside the lungs) is lower than inside the lungs.

Question 6

Step 6 Of Expiration

Answer 6

Air flows out of the lungs down a pressure gradient. This is expiration - one breath out.