Introduction to the Human Respiratory System

Simple diagram of the lower respiratory tract. (Click here for a more detailed diagram.)

This page gives a very simple overview of the structure and functions of the human respiratory system.

About Respiration

Respiration consists of:

  1. Breathing (inspiration and expiration),
  2. Gaseous Exchange (exchange of gases between the lungs / blood and blood / tissues and vice-versa).

It is controlled by the autonomic nervous system (ANS),
specifically the medulla oblongata.


Basic Structure of the Respiratory System

Below is a very simple diagram in which the respiratory system is represented by a flow-chart indicating the route by which oxygen flows into the body via the airways then travels to the surfaces at which gaseous exchange with tissues occurs:

Upper Respiratory Tract :






Lower Respiratory Tract :
(Click to view this section as a diagram instead)







Although the above is a good starting point from which to memorise the structures one might need to identify in an exam, further detail will be needed when asked to "describe by means of a diagram", or similar. All but the simplest texts illustrate the upper-respiratory tract and the lower-respiratory tract separately.


Facts about the Human Respiratory System

  • There are two lungs in the body, the total surface area of both of these combined being equivalent to that of about 2 tennis courts (per normal adult).
  • All of the blood in the body circulates through the lungs each time it passes around the body.
  • If laid end-to-end the capilliaries of the lungs would stretch for approx. 44 miles (70 km).

See also information about other aspects of the respiratory system incl. notes about pulmonary circulation.

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This is not medical, First Aid or other advice and is not to be used for diagnosis or treatment. Consult an expert in person. Care has been taken when compiling this page but accuracy cannot be guaranteed. This material is copyright.

IvyRose Holistic Health 2003-2017.