Is divided to the external nose and internal nasal cavity, when you breathe in, air enters the cavity by passing through the nostrils. Hairs trap pollen and other foreign particles. A sticky mucous layer traps smaller particles in the nasopharynx.

Small flap of cartilage at the back of the tongue, closes the top of the trachea to stop food and drink passing into your lungs .

Connects the natal cavity and mouth to the larynx. The wall is made up of skeletal muscle.

Also known as the voice box, has rigid walls of muscle and cartilage, contains the vocal cords and connects the pharynx to the trachea.

Also known as the windpipe, contains rings of cartilage to prevent it from collapsing and it is very flexible. It branches out to the left and right bronchi.

These are formed by a division of trachea, they carry air to lungs, the right bronchus is shorter and wider than the left and is more common site for foreign objects becoming lodged.

Small airways that extend from the bronchi. They are about 1mm in diameter and do not contain cartilage.

This occupy most of the thoracic cavity and extend down to the diaphragm. The left lung is smaller than the right.

Each lung is divided into lobes, the right lung has 3 and the left has 2.

This is the chamber of the chest that is protected by the thoracic wall, it is separated from the abdominal cavity by the diaphragm.

The bronchioles end in air sac which are called alveoli, there are 300 million gas-filled alveoli in each lung, which provide an enormous area for gas exchange. This is roughly the size of a tennis court.

This separates the chest from the abdomen. It is the most important muscle involved in breathing. Contraction of the diaphragm increases the volume of the chest cavity, drawing air into the lungs, while relaxing involves recoil of the diaphragm and decreases the volume of the cavity, pumping air out.