10.8 Circulation and Respiratory Systems

10.8.2 Describe the basic anatomy (structure) of the respiratory system.

The respiratory system consists of:

• the nose and mouth;
• the trachea;
• the bronchi;
• the bronchioles;
• the lungs; and
• the alveoli.

Air enters through the nose or mouth and passes down the trachea, or windpipe.

The trachea divides into two bronchi, one leading to each lung.

Inside the lungs, the bronchi divide into smaller tubes called bronchioles.

At the ends of the bronchioles are tiny air sacs called alveoli.

Key point

Trachea → bronchi → bronchioles → alveoli.

10.8.4 Describe the physiology (function) of the respiratory system.

The main function of the respiratory system is to:

• take oxygen into the body; and
• remove carbon dioxide from the body.

When we breathe in, air travels into the lungs and reaches the alveoli.

At the alveoli:

• oxygen passes from the lungs into the bloodstream; and
• carbon dioxide passes from the bloodstream into the lungs to be exhaled.

This process is called gas exchange.

Key point

The respiratory system supplies oxygen and removes carbon dioxide.

10.8.6 Describe the basic anatomy (structure) of the circulatory system.

The circulatory system consists of: