The Respiratory System

Your respiratory system brings oxygen into your body and helps to remove carbon dioxide. Problems with your respiratory system can reduce the oxygen that reaches your lungs, which can make you unwell.

Parts of the respiratory system

Your respiratory system consists of the:

  • nose
  • pharynx
  • larynx
  • trachea (windpipe)
  • bronchi (branching from the trachea, and leading to smaller bronchioles)
  • lungs

Your lungs are in your chest, protected by your ribcage. You breathe in by contracting your diaphragm, a flat muscle at the base of your chest. This causes the chest to expand, drawing air in.

Air passes into your nose and through the upper airways to reach your lungs.

In your lungs, air sits in small air sacs called alveoli, which are right next to blood vessels. Oxygen travels from your alveoli into your bloodstream, and carbon dioxide travels the other way from your bloodstream into your alveoli. You then breathe it out.

The Upper Respiratory Tract

The upper respiratory tract includes the nostrils, mouth, nasal cavity, throat (pharynx) and the voice box (larynx). The throat is the main passage for both food and air. It starts from the cavity at the back of the nose and mouth and extends down to where it divides into two separate tubes, the trachea and the oesophagus. The trachea allows the passage of air to and from the lungs.

The upper respiratory tract is the most common location for an airway obstruction.

When you breathe in, air enters through the nose. The nasal cavity warms and filters the air we breathe before it enters the trachea. The trachea then divides into the left and right bronchi.

The Lower Respiratory Tract

The lower respiratory tract consists of the trachea (windpipe), bronchi and lungs, which then divide into two, going into the left and the right lung. The bronchi then progressively divide into small bronchioles and eventually end up as alveoli and alveolar sacs which are small air sacs in the lungs. This is where the oxygen we breathe in enters the blood stream and when we breathe out this removes waste product (carbon dioxide) from the blood stream. The lungs fill most of the chest cavity, which is separated by the abdomen by a large sheet of muscle, known as the diaphragm.