Respiratory System (4)

The structure of the human respiratory system (11)

Intercostal muscles

The structure of the human respiratory system (12)

Bronchus

The structure of the human respiratory system (13)

Larynx

Direction of air in breathing mechanism

Nostrils > Nasal cavity > Pharynx > Larynx > Trachea > Bronchus > Bronchiole > Alveolus

Mechanism of inhalation (1)

When you inhale, intercostal muscles contract and pull the rib cage upwards and outwards

Mechanism of inhalation (2)

Diaphragm muscles contract and pull the diaphragm to descend and become flat

Mechanism of inhalation (3)

Movements of the rib cage and diaphragm make the thoracic cavity bigger and cause air pressure in the thoracic cavity to decrease

Mechanism of inhalation (4)

The higher air pressure outside forces air to enter the lungs

The action of epiglottis during swallowing of bolus

Epiglottis drops down and closes the trachea when a bolus is swallowed into the esophagus

The action of epiglottis during breathing

Epiglottis moves up causing the trachea to open