Movement of molecules in and out of cells: Gaseous exchange in the lungs

Breathing:

• Ventilation is the movement of air into and out of the lungs.
• Air passes through the mouth/nose → trachea → bronchi → bronchioles → alveoli.
• The diaphragm and the intercostal muscles are used in ventilation.
• Breathing in or inhaling means the diaphragm and intercostal muscles contract.
• Breathing out or exhaling means the diaphragm and intercostal muscles relax.

What does Ventilation mean?

Ventilation means breathing in and out.

What does Diaphragm mean?

A large sheet of muscle that separates the lungs from the abdominal cavity.

The process of Ventilation:

Inhaling: 

1 - Air is taken through the mouth/nose.

2 - Intercostal muscles contract, expanding the ribcage.

3 - Pressure decreases in the lungs so air is able to be pushed in.

4 - Diaphragm contracts, pulling downwards. 

Exhaling:

 1 - Diaphragm relaxes and moves up.

2 - Pressure increases in the lungs so air is able to be pushed out.

3 - Intercostal muscles relax, allowing the ribcage to…