Blood, Sweat, and Tears: Human Anatomy

Respiratory System


There is one and only one: gas exchange. The respiratory system shifts around oxygen to make sure it's accessible for the body, and gets rid of anything else the body doesn't want. 

Mouth and Nose

These are the main entry ways for gases, carrying oxygen and everything else into the larynx. The mouth and nose are also the exit passages for anything the respiratory system is getting rid of. 

The Trachea

The trachea is very simple tube, or "pipe", that carries gasses down to the bronchi. It features a flap, known as the epiglottis, that keeps food from coming down the trachea. 


The larynx isn't actually involved in any gas exchange per se; rather, it uses the air passing from the mouth and nose to the lungs to produce a sound, otherwise known as our voices. This earns the larynx the nickname of "voicebox".


In order to actually move gases in and out of the body, the diaphragm contracts to change pressure levels in the lungs and "suck" air in. When it relaxes, it moves up and "pushes" air out. 


From the trachea descends two branched structures known as the bronchi (singular is bronchus). The original two bronchi branch off into secondary bronchi and tertiary bronchi, which finally branch off once more into bronchioles. These bronchioles function similarly to villi in that they increase surface area to allow for a greater absorption, in this case being gases. 


Each bronchiole connects to an alveoli, and this is where the actual gas exchange takes place. Alveoli are small, bulbous air sacs that take all the gases and move them from the lung to the bronchi and vice versa. 


The lungs are what encase all the bronchial and alveoli tissue.