The Respiratory System
Mr. Glatt
14-15
The Respiratory System
Function of the Respiratory System
• To bring about the exchange of oxygen and carbon
dioxide between our blood and the air
– Oxygen in
– Carbon dioxide out
• Why is this important?
– Cells need oxygen to complete cellular respiration
• Glucose + Oxygent  Cabon Dioxide + Water + ATP (Energy)
– Carbon dioxide produced in this process becomes toxic
to the body if it is not removed
Structures
Nose and Nasal Cavity
• Provides a passageway for air to enter the
body during respiration
– Air is filtered, moistened and warmed as it passes
through these structures
Structures
Pharynx
• Passage from the back of the mouth and
nasal cavity that leads to the trachea & larynx
– Commonly known as the throat!
Structures
Trachea
• The trachea is the tube that provides a
passageway for air from the pharynx (throat)
to the lungs
– Commonly known as the windpipe
– At the top of the trachea is a flap of tissue called
the epiglottis
• The epiglottis closes off the trachea when we swallow
– The larynx or voicebox is also located at the top of
the trachea
• It contains vocal cords
Structures
Bronchii
• The bronchii are the two large airways that
branch out from the trachea and enter the
right and left lung.
– Each large bronchus branches out into smaller and
smaller bronchii
Structures
Bronchioles & Alveoli
• Bronchioles are the smallest passageways in the
lungs. Each bronchiole leads into a clump of alveoli
• Alveoli are tiny air
sacs that are clumped
together like bunches of
grapes
– Alveoli are surrounded by
capillaries (thin walled blood
vessels)
– Alveoli have very thin walls
– This is where oxygen and
carbon dioxide are
exchanged between the
lungs and the blood
Gas Exchange
• Inhaled Air
– 21 percent OXYGEN gas
– .04 percent CARBON DIOXIDE gas
• Exhaled Air
– 15 percent OXYGEN gas
– 4 percent CARBON DIOXIDE gas
How Breathing Works
• At the bottom of the chest cavity is a muscle called
the diaphragm
• When the diaphragm contracts it causes the chest to
expand
• When the chest expands a vacuum is created
– Low pressure air inside lungs
– Higher pressure outside lungs
• Air then rushes into lungs due to pressure difference
• When diaphragm relaxes chest gets smaller and air is
forced out due to increased pressure inside chest
What Regulates
Breathing Rate?
• Breathing rate is under autonomic control although we
have the ability to consciously control our breathing
rate
• The medulla oblongata is a specialized portion of the
brain that regulates or breathing rate
– Measures and monitors carbon dioxide levels in the blood
• As carbon dioxide levels increase the medulla oblongata
sends impulses to the diaphragm to contract more
quickly causing breathing rate to increase