Draft:Respiratory system

Without the Respiratory system in our body, we wouldn't be able to breathe, and live.

Anatomy of the Respiratory System
In the order in which the air typical passes through the respiratory system:

Nasal Passage (Nose)
When we breathe in, the air can be dry and cold, and may have particles in it. The nasal passage helps to warm up air, and increases the amount of moisture in the air.

Filter system of the nasal passage
The nose-hairs catch large particles, helping to stop them from going further into the body.

The mucus (snot, or the "green-slime" in your throat) lines the walls of the nasal passage. As mucus is sticky, most small particles that don't get caught by the nose-hairs get stuck to this.

Picking your nose essentially clears these filters! If someone doesn't breathe in through their nose (and instead breathes in through their mouth), the air skips this filter system.

Oral Passage (Mouth)
When air is breathed in through the mouth, instead of the nose, the air is typically drier, colder, and more dirty.

Pharynx
The pharynx connects/merges the path for the nasal (nose) and oral (mouth) passages.

Epiglottis
The larynx is a flap of skin, just above the larynx, which can open and close in order to stop food and drink from going into the larynx (voice-box), towards the lungs. When it is closed, it instead forces the food or drink into the esophagus (towards the stomach).

Larynx (Voice-box)
Inhaled air goes through the larynx (voice-box). This voice-box contains muscles which can control how the air leaves the body, in order to help form words.

Trachea (windpipe)
The trachea (windpipe) is a long tube which the air passes through to get to the lungs. It connects the larynx to the lungs.

Carina
The carina is where the trachea (windpipe) splits into the left and right main-bronchus.

Bronchi
The bronchi are the tubes which connect the trachea to the alveoli.

Main bronchus: when you are talking about the main section of the bronchus, before it has split up into the bronchi, you call it the 'Main bronchus', or 'Main bronchi' if you are talking about more than 1 of them.

Lobar bronchus: when you are talking about the divided section of the bronchus, after the main bronchus has split up, you call it the 'lobar bronchus', or 'lobar bronchi' if you are talking about more than 1 of them.

Due to the way the bronchus is formed, if an object managed to get into the bronchi, it is more likely to fall into the right main bronchus due to gravity, as it has more of a slope than the left main bronchus;

Alveoli + alveolar ducts
The alveoli mark the end of the bronchi path.

The alveolar ducts are tiny, and they connect the respiratory bronchioles to the alveolar sacs, which contain a collection of alveoli.

The alveoli have a very thin wall, which allows oxygen to pass through it into the blood, and for carbon dioxide to leave through the wall, into the lungs.

When you breathe in, and the lungs expand to do this, the alveloi inflate (and become much larger in size) as they are being stretched open.

The alveoli are covered in the protein elastin, which allows them to stretch out. When the intercostal muscles and diaphragm relax, this elastin naturally recoils; this means the alveoli won't remain puffed up, which would mean that air would not be replaced properly; this is also the main reason for the lungs shrinking in size.