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The respiratory system involves the movement air from the atmosphere into
your body so that your lungs can transfer the oxygen from that air
into your blood. It also allows CO2 to be removed from your blood
so that your body can expel it. We need oxygen so that our cells can function.
It's a crucial molecule in producing ATP. ATP is needed for all the different
types of reactions that occur in our cells.
At certain times the cells in our body require more oxygen
so our body compensates by changing respiration
meaning how often and how much air we breathe in.
Here's what we'll be looking at today. The main functions of the respiratory
system.
The anatomy of the respiratory system. External respiration.
or how gases are exchanged between our bodies and the atmosphere.
And internal respiration or how oxygen and carbon dioxide are exchanged between
the blood
and the cells and our tissues. So to start off
let's first take a look at what the respiratory system does. It provides a large
surface area for gas exchange.
It provides protection from any drying out
or dehydration of the respiratory surfaces. Provides defense
against pathogens that get into our system. It helps to produce sounds
like speech or singing. And it helps in the sense a smell.
There are olfactory receptors
for smell in your nasal cavity. Okay,
so let's dive into the upper respiratory system. The upper respiratory system
consists
of the nose, nasal cavity
sinuses and the pharynx. What these structures help to do is filter
warm and humidify incoming air. This helps to protect the more delicate surfaces
of the lower respiratory system. The upper respiratory system
also helps to reabsorb heat as well as water from the air that is expelled
from our lungs. If we take a look at the pharynx
you can see that it is divided up into three different areas.
The nasopharynx, the oropharynx
and the laryngopharynx. The nasopharynx
is the superior portion the pharynx seen here. The
oropharynx is located between the soft palate and the bottom part or the
base
of the tongue and the laryngopharynx extends until the entrances of
the larynx and esophagus. The lower respiratory system consists of
the larynx, trachea, bronchi,
bronchioles, smallest bronchioles,
and the alveoli. These structures allow for gases to be exchanged
from the lungs to the blood and vice versa. Air enters the trachea and flows
downwardly.
The trachea is surrounded by approximately 20 cartilages
that provide stiffness to the tracheal walls. This is for protection
of your wind pipe.So as air descends down the trachea,
it travels towards two large tubes that are called the primary bronchi.
There is a right and left primary bronchus.
What's interesting here is that the right bronchus has a greater diameter
and is situated at a much steeper angle then left bronchus
so when someone accidentally aspirates an object that enters the trachea
often that object will enter the right bronchus. As the air we inspire continues
through the respiratory tract,
it enters smaller bronchi and eventually the bronchioles.
Bronchioles are extremely interesting because they have the ability to
increase and decrease their diameter. This is accomplished by
thick layers of smooth muscle in the walls are the bronchioles. The
increase in diameter is called broncodilation and the decrease
is called bronchoconstriction. So
eventually air reaches the alveoli. This is where gas exchange takes place.
Alveoli are clusters of air sacs that look like bunches of grapes.
They allow for oxygen to get into our blood and for carbon dioxide to leave
the blood.
The oxygen is then transported to our tissues that require the oxygen
to make ATP. And the CO2
is transferred and expelled out of our system and into the atmosphere.
Within the lungs there is an immense amount of vascularity.
This allows for oxygen to enter the blood and oxygenate it
while allowing blood to unload carbon dioxide.
In this diagram you can see a close-up have an alveolus
and a pulmonary capillary. The areas of exchange in the lungs contain very very
thin membranes.
The reason for this is that it makes diffusion distances for oxygen and
carbon dioxide
much shorter and thus easier.
As you can see oxygen moves from the alveolar air space
into a pulmonary capillary and then into a red blood cell
which is what is used to carry oxygen within our blood.
At the same time carbon dioxide moves out of the red blood cell
through the pulmonary capillary and into the alveolar air space.
When we exhale the CO2 moves up the respiratory tract
and out of our mouths into the surrounding atmosphere.