The respiratory system allows humans to breathe and obtain oxygen while removing carbon dioxide. It includes the nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles and lungs. The nasal cavity and mouth allow air to enter, which then passes through the pharynx and larynx before entering the trachea and branching bronchi that lead to the lungs. Within the lungs are clusters of tiny alveoli sacs where the exchange of oxygen and carbon dioxide occurs through thin walls, allowing oxygen to enter the bloodstream and carbon dioxide to be removed.

1. The Respiratory
System
7SCIENCE
Fri., Nov. 19

2. Why study the respiratory system?
• What do humans need to survive?
• Humans need many things to survive, one is
food and the other is air
• We are ALWAYS breathing
• Breathing:
– the process where fresh air
moves into your lungs and
stale air moves out of your lungs

3. Connected to the digestive system
• The digestive system prepares and stores
energy from digested food in your cells
• Respiration: the process of releasing this
energy through using oxygen
– Oxygen is required to release the energy from cells
• Carbon dioxide (what we
breathe out) is a waste
product from this respiration

4. Main organs of the respiratory system
• Nasal cavity
• Pharynx
• Larynx
• Trachea
• Bronchi (Bronchioles)
• Lungs

5. Nasal Cavity, Pharynx, Larynx
• Nasal cavity: Air enters
through your nose or
mouth
• Pharynx
– Tube that food and air pass
through
– Epiglottis: a flap of muscle
that prevents food from
entering the larynx
• Larynx
– Airway that attaches to
vocal cords
• As air passes over vocal
cords, the muscles vibrate
and tighten or loosen to
make a sound (speaking!)

6. Trachea, Bronchi
• Trachea:
– Found below the larynx
and is made of cartilage
rings
• Bronchi:
– At the end of the trachea
you have branches that
carry air into the lungs
– These split into smaller
branches called
bronchioles

7. Lungs, Alveoli
• Lungs:
– Take up most of the space
in the chest
– Bronchi enter the lungs
and split into bronchioles
(smaller tubes)
– At the end of these tubes
are clusters of tiny sacs,
called alveoli
• Alveoli
– Where exchange of oxygen
and carbon dioxide takes
place
– Happens easily because
alveoli have walls that are
one cell thick