Respiratory System
Review
 What is air?
21% oxygen
 78% nitrogen
 0.03% carbon dioxide

 Why do we need air?
O2 + Glucose
Water + CO2+Energy
The Respiratory
System
Functions
1. Take oxygen from the
atmosphere and deliver
it to the bloodstream.
2. Take carbon dioxide
from the bloodstream
and expel it from the
body.
This system works closely
with the circulatory system.
The Respiratory System
Nasal Cavity: 2 cavities that contain hairs, cilia, mucous
and a rich blood supply
Function:
• Hairs and cilia filter particles
• Mucous traps particles and moistens the air
• Blood vessels warm air up to body temperature
The Respiratory System
Pharynx: muscular region at back of
mouth
Function:
• Passageway for air and food
Trachea: long tube lined with cilia (tiny
hairs) and mucous
: made up of cartilage rings
Function:
• Allows air to travel to and from the
lungs
• Cilia help filter out and remove dirt
and bacteria from entering the lungs.
• Dirt and bacteria are pushed up into
the esophagus
Cilia cells
in the
trachea
The Respiratory System
Epiglottis: flap of skin at the top
of the larynx
Function:
• Prevents a bolus of food from
entering the trachea
Larynx: box shaped part, made of
cartilage and elastic folds called the
vocal cords.
Function:
• Produces sound
larynx video
The Respiratory System
Bronchi: 2 branches of trachea
that contain carilage rings, mucous,
and cilia
Function:
• Delivers oxygen to each lung
Bronchiole: smaller branches of
bronchi without cartilage and lined
with smooth muscle
Function:
• Deliver oxygen to alveoli
The Respiratory System
Alveoli: (alveolus = singular)
: small grape like sacs
at the end of the bronchioles
to maximize surface area
: measures 0.2 um in
diameter
Function:
• Allows for the diffusion of
gases (O2 and CO2)
between the air and blood.
The Respiratory System
Alveoli:
Do Not Copy
• wall of alveolus is one cell layer thick
• 150 million per lung
• Have a combine surface area of 90 m2
• Surrounded by a network of capillaries (circulatory system)
This is where the Circulatory System and the
Respiratory System meet and exchange gases!
The alveolus is covered by capillaries, which
carry the blood to the body.
 O2 moves from the alveolus
to capillaries through
diffusion - movement from
high concentration to low
concentration. aka Inhaling
 CO2 moves into alveolus by
diffusion, collected from all
the alveoli in the lungs and
pushed back up and out the
trachea to the mouth and
nose. aka Exhaling
Video
Pig lungs
Question: How do you know
when to inhale and exhale?
 Breathing is involuntary, it is controlled by a part
of the brain (Medulla Oblongata) that detects the
concentration of CO2.
 If CO2 is high, the brain
increases breathing.
 If CO2 is low, the brain decreases breathing.
Homeostasis!!!
Mechanics of Breathing
(How do we breathe?)
 Inhaling:
 rib
muscles pull out and up,
while diaphragm muscle
contracts pulling down
 Chest cavity volume
increases resulting in a
decreased air pressure
 Air moves from area of high
pressure (atmosphere) to
low pressure (in the lungs)
Mechanics of Breathing
(How do we breathe?)
 Exhaling:
 Rib
muscles and
diaphragm relax
 Chest cavity volume
decreases resulting in an
increased air pressure
 Air moves from area of
high pressure (in the
lungs) to low pressure
(atmosphere)
Breathing:
Animation
Animation 2
Respiratory Diseases:
•Asthma
•Chronic Bronchitis
•Emphysema
•Pneumonia
•Influenza
•Tuberculosis
Asthma
 Bronchi are temporarily swollen and mucus restricts
air flow. Person finds it hard to breath
Chronic Bronchitis
 Bronchi are permanently swollen and have too much
mucus. Person often coughs and breathless due to
less O2
Emphysema
 Alveoli (air sacs)
collapse and/or are
destroyed
permanently. Less
gas exchange =
harder to get O2
Pneumonia
 Alveoli fill with fluid
caused by bacteria or
viruses causing
coughing, chest pain,
fever, etc.