IGCSE GCSE 0610 Biology Human Breathing System Lung

A. STRUCTURE



Larynx
Alveoli (air sacs)


Intercostal muscle Trachea (windpipe)
(internal)


Bronchus
Cartilage rings

Lung
Bronchiole


Intercostal muscle
Rib
(external)




Diaphragm




• The trachea is lined with cartilage rings. These:

- support and protect the trachea

- allow the trachea to flex for breathing




• There are two sets of muscles that move the ribcage:

- internal intercostal muscles

- external intercostal muscles




Air moves from high  low pressure

, B. HOW WE BREATHE IN AND OUT


Inhaling



External
intercostal
muscles
contract
VOLUME IN CHEST (THORAX) INCREASES
Ribcage
PRESSURE IN CHEST (THORAX) DECREASES
moves
up and out
AIR MOVES FROM HIGH  LOW PRESSURE

AIR ENTERS THE CHEST




Diaphragm
contracts
(moves down)




Exhaling



Internal
intercostal
muscles Ribcage
contract moves
down and in


VOLUME IN CHEST (THORAX) DECREASES

PRESSURE IN CHEST (THORAX) INCREASES

AIR MOVES FROM HIGH  LOW PRESSURE

AIR LEAVES THE CHEST



Diaphragm
relaxes
(moves up)