Download The Respiratory System

The Respiratory System
Role of the Respiratory System
• The main role of the respiratory system is to
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get oxygen from the atmosphere and place it in
a dissolved form into the blood.
The blood will then deliver the oxygen to the
cells of the body so they can run cellular
respiration and make energy in the form of ATP.
Ironically, the other thing needed to make ATP is
glucose and we already learned how that was
dealt with by the digestive system and placed
into the blood.
Glucose + O2  CO2 + H2O + ATP!!!
Types of Respiration
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There are three types of respiration:
External Respiration – The exchange of gases across the
inner surface of the lungs. (Alveoli & Blood)
Internal Respiration – The exchange of gases between
the blood and cells. (Capillaries & Cells)
Cellular Respiration – The use of the oxygen to make
energy (ATP) inside of the cell and the mitochondria.
Carbon dioxide is a waste gas that is produced by this
process and it must be removed from the cells because it is
toxic to the cells.
The movement of both oxygen into the cells, and carbon
dioxide out of the cells is carried out by diffusion.
Diffusion is a mode of passive transport in which substances
move from an area or high concentration to an area of low
concentration.
The Respiratory Pathway (I)
• Air enters the body through either the oral cavity
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(mouth) or nasal cavity (nose).
The nasal cavity does a better job of preparing
the air for the “wimpy” lungs.
– It warms the air with increased surface area
and the large numbers of capillaries inside.
– It moistens the air with mucus.
– It cleans the air with nose hair, ciliated cells
and mucus – sounds funny but it’s snot!
Both the nose and mouth lead back to the
pharynx – the intersection at the back of the
throat.
The Respiratory Pathway (II)
• After the pharynx, air moves
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down past the larynx (voice
box).
There are a pair of cartilage
flaps called the vocal cords
inside the larynx that vibrate
as air is pushed by them.
Your teeth, lips and tongue
mold the noise produced by
the vocal cords help you
pronounce various sounds.
The epiglottis lies above
the larynx.
The trachea lies below the
larynx.
The Respiratory Pathway (III)
• The trachea is the windpipe. It extends down
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from the throat to the chest cavity.
The trachea is protected by cartilage rings
that keep it from collapsing and cutting off you
air supply.
It also has mucus-producing cells and cilia
lining its inner surface to trap dirt and pathogens
and prevent lung infection.
The base of the trachea divides into two
branches – the left and right bronchi – each of
which leads into the left and right lung.
The Bronchial Tree
• The bronchi, at the base
of the trachea, begin to
branch out into smaller
bronchioles inside of
the lungs.
• The bronchioles spread
outward to the outer
edges of the lungs until
you reach the alveoli.
• This branching pattern is
known as the bronchial
tree.
Gas Exchange
• Gas exchange takes place
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in the alveoli of the lungs.
This is where oxygen (O2)
is put into the body while
carbon dioxide (CO2) is
removed from it. This
movement is governed by
diffusion. (HI  LOW)
The alveoli look like small
bunches of grapes that are
surrounded by capillary
nets.
Capillaries are exchange
sites in blood vessels.
The Physiology of
Respiration
Muscular Control of Breathing
• Breathing is under control of a layer o smooth muscle,
called the diaphragm, that lies just below the lungs.
• The lungs reside in the thoracic cavity – the hollow
compartment in the chest. The lungs are like sponges
and can expand or constrict to fit within the space of
the thoracic cavity.
• The diaphragm contracts and moves downward – this
makes the thoracic cavity larger and the lungs expand
and take in more air to fill the space. This is
inhalation.
• When the diaphragm relaxes, it moves back up and
makes the thoracic cavity smaller – the lungs are now
squeezed and the air is forced out of them. This is
exhalation.
Muscular Control of Breathing
Nervous Control of Breathing
• The medulla oblongata is the part of the brain
that controls your breathing rate. It has
chemoreceptors in it that measure the acid levels
of blood. (pH is the key.)
• As more CO2 is dumped into the blood by the cells,
there is more need to breathe and get rid of that
CO2. The CO2 mixes with the water in the blood to
form carbonic acid.
CO2 + H2O  H2CO3 (aq)
• More CO2 means more carbonic acid in the blood
and a lower pH. This is sensed by the medulla
oblongata and it sends an impulse down to the
diaphragm to move faster and your breathing rate
increases.
That’s All I Got…