Download principal structures (student review)

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The respiratory system (or ventilatory system) is responsible for the
exchange of oxygen and carbon dioxide.
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Oxygen is required by all the cells in the body to function so the ventilator
system brings in oxygen and gets rid of carbon dioxide.
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Air travels through some tubes and pathways before it reaches it’s
destination.
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Air enters through the nose or mouth.
It then travels through the Pharynx commonly known as the throat.
Then into the Larynx commonly known as the voice box.
Into the Trachea and then the bronchi, bronchioles, the lungs and then the
alveoli.
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Gaseous exchange only occurs at the alveoli, nothing else takes part in gas
exchange.
If we start with the nose, air travels through the nose. The nose is protected by
hairs, which act as an air filter so we don’t breath bad things into our lungscatches the dust and particles. It also has a sticky mucous membrane which
basically moistens and warms the air before it travel down through the pharynx.
Then we have the pharynx (throat), which can be divided into 3 separate
regions. It is part of the respiratory and digestive system. It goes from the back of
the nasal cavity to the voice box.
1. Part close to the nasal cavity is called the nasopharynx
2. Part close to the oral cavity is called the oropharynx
3. Part close to the Larynx is called the laryngopharynx
Larynx has 3 functions:
1. Produce sound
2. Protects airways- prevents food and foreign substances from entering the
airways.
3. Passageway for air during breathing.
It’s mostly cartilage but also has some smooth muscle and ligaments attached to
it. It contains the epiglottis, which is a cartilage flap that looks like a toilet seat
cover. The epiglottis flaps down and covers the larynx to keep food and foreign
substance from entering the lungs. When we swallow our larynx moves up and
forwards and the epiglottis flaps down to cover the larynx so food and liquids
don’t go into our lungs.
The epiglottis is flap of cartilage located in the throat behind the tongue and in
front of the larynx. The epiglottis is usually upright at rest allowing air to pass
into the larynx and lungs. When a person swallows the epiglottis folds backward
to cover the entrance of the larynx so food and liquid do not enter the windpipe
and lungs. After swallowing the epiglottis returns to its original upright position.
Then we go down into the Trachea, which we call the windpipe. Trachea is held
open by rings of cartilage.
The trachea branches out into the 2 main bronchi- right and left.Branches into
the two main bronchi which is plural for bronchus.
The bronchi look like an upside down tree.
Big tree trunk (trachea) branches into 2 smaller primary branches- Bronchi,
which eventually branch out into Bronchioles. Branches become more numerous
and smaller as you go into each lungs. Cartilage (keeps airways open) disappears
to be replaced by smooth muscle by the time you get to the bronchioles. At the
end of the bronchioles there are small air sacs that look like clusters of grapes.
These air sacs are called the alveoli.
Alveoli where the gaseous exchange occurs. There is around 3 million alveoli in
each lung. Lots of surface area, thin walled of thin flat cells for easy diffusion so
stuff can move with rapid diffusion; surrounded by a blood supply.