Ventilation

—> ventilation is the movement of air in and out of the lungs

—> involves the intercostal muscles

—> and diaphragm contracting and relaxes

—> to change the size of the thorax

Inspiration : breathing in -> energy - using process because muscles contract.

• the diaphragm contracts, flattening and lowering
• the external intercostal muscles contract moving the ribs upwards & outwards
• increase the volume of the thorax which decreases the pressure in the thorax
• pressure falls between atmospheric pressure
• air is drawn in through the nasal passages, trachea, bronchi and bronchioles into the lungs down a pressure gradient

Expiration : breathing out -> passive process because muscle relax

• the diaphragm relaxes so move into it’s domed shape
• the external intercostal muscles relax moving the ribs downwards and inwards
• decreases the volume of the thorax, so the pressure is increased
• higher than the atmospheric pressure
• air moves out through the nasal passages, trachea, bronchi and bronchioles out of the longs down a pressure gradient
• elastic fibres in alveoli return to normal length forcing air out

—> when someone has a fever lung infection or respiratory muscle weakness, they struggle to ventilate themselves

—> a ventilator is used in hospitals to help those that can’t ventilate properly themselves