The Respiratory SystemThe function of the respiratory system is simple, to bring oxygen into the body and to expel carbon dioxide.

BreathingThe process of breathing starts with the diaphragm. When you inhale, the diaphragm contracts, raising the rib cage and the volume of the chest cavity.

This lowers the pressure in the cavity and as a result, outside air rushes into your lungs.

BreathingWhen your diaphragm relaxes, the volume of your chest cavity returns back to normal. This increases the pressure inside the chest cavity and air is pushed out of your lungs.

Try it! Feel how your chest rises and falls with each breath you take!

Breathing

The Mouth and Nasal Passages

Air enters through your mouth and nose. Once inside, air is pushed down the trachea toward the lungs.

Furthermore, the air is warmed by your nasal cavity before entering the larynx.

The Mouth and Nasal Passages

Air going through the nose is also filtered by your nose hairs, which can catch bacteria, pollen, other allergens, etc.

This, of course, can lead to dried nasal mucus. What do you think this term refers to?

The Larynx

After going past the nasal cavity, air enters the larynx before entering the trachea.

Keep in mind the most important structure within the larynx are your vocal cords and the muscles that control them!

The Trachea

The trachea is the air passage connecting the larynx to your lungs.

Near the lungs, the trachea branches into two bronchi, which in turn enter each of your lungs.

Bronchi and BronchiolesLining the trachea are mucous membranes and cilia.

Like nasal hair, this is a defense mechanism of your respiratory system designed to catch foreign particles and pathogens.

Anything caught is transported upwards back through the larynx as phlegm.

Bronchi and Bronchioles

Meanwhile, as we follow air, it moves from the bronchi into smaller passageways known as the bronchioles, and finally ends at the alveoli.

AlveoliAlveoli are structures in your lungs that allow gas exchange to take place.

Deoxygenated blood from the pulmonary arteries enter capillaries around alveoli, where they pick up oxygen and drop off carbon dioxide.

Once oxygenated, the blood moves into the pulmonary vein for transport back to the heart.

Alveoli

Removal of Carbon DioxideWith gas exchange complete, carbon dioxide is now found in the alveoli space.

When you exhale, the carbon dioxide goes up through the bronchioles, the bronchi, then the trachea, past the larynx, and finally expelled from the mouth or the nose!