Respiratory System


Respiratory System

The respiratory system is under control of both the involuntary and voluntary nervous system. Humans don’t have to think about breathing. The (autonomic) involuntary nervous system controls breathing in response to carbon dioxide levels in the blood.

Humans can decide to hold their breath, such as when they dive underwater. The respiratory system is then controlled by the somatic nervous system. If a person passes out because they voluntarily hold their breath, the autonomic nervous system will take over until the blood gasses return to normal.

When you inhale, the diaphragm and intercostal muscles (the muscles between your ribs) contract and expand the chest cavity. This expansion lowers the pressure in the chest cavity below the outside air pressure. Air then flows in through the airways

(from high pressure to low pressure) and inflates the lungs. When you exhale, the diaphragm and intercostal muscles relax and the chest cavity gets smaller. The decrease in volume of the cavity increases the pressure in the chest cavity above the outside air pressure. Air from the lungs (high pressure) then flows out of the airways to the outside air (low pressure). The cycle then repeats with each breath.

You breathe in and out anywhere from 15 to 25 times per minute without even thinking about it.

Answer the following questions


What organs allow the respiratory system to function?


What is the function of the respiratory system?

· What body systems work together to help the circulatory system?