Unit 5: The Respiratory System

What is Respiration?

Upper Respiratory Tract:
- Nose: Cartilage and two nasal bones, mucosal membranes, cilia, two chambers divided by a septum.
- Pharynx: Muscular and fibrous tissue, air passage, connects with the nose.
- Larynx: Tube between tongue and trachea, cartilage rings, passageway for air, voice production.
Lower Respiratory Tract:
- Trachea: 10 cm long, tubular pipe, divides into two bronchi, cartilage rings, mucosal membranes.
- Bronchi: Branches of respiratory tube, hyaline cartilage, involuntary, lined with ciliated epithelium.
- Bronchioles: Extensions of bronchi, muscular, fibrous, elastic tissue, connect to alveoli.
- Alveoli: Tiny sacs, gas exchange, surrounded by capillaries.
- Lungs: Two lungs, cone-shaped, spongy tissue, bronchioles, alveoli, blood vessels, nerves, lymph vessels, pleura-covered.
- Diaphragm and Intercostal Muscles:
  - Diaphragm: Large muscle between chest and abdomen, central tendon, muscle fibers, assists in breathing.
  - Intercostal Muscles: Lie between ribs, aid the diaphragm during breathing.

Nose:
- Warms, moistens, and filters air.
Pharynx:
- Air passage, warms and moistens air.
Larynx:
- Passageway for air, filters bacteria, aids voice production.
Trachea:
- Passageway to bronchi, traps foreign particles.
Bronchi and Bronchioles:
- Transport oxygen and CO2, connect to alveoli.
Alveoli:
- Gas exchange between circulatory and respiratory systems.
Lungs:
- Oxygen intake, carbon dioxide removal.
Diaphragm:
- Contracts for inhalation, relaxes for exhalation.
Intercostal Muscles:
- Contract and relax to aid in changing the chest cavity size during breathing.

Air is warmed, moistened, filtered through the nose and mouth.
Passes through trachea, bronchi, into lungs, bronchioles, and alveoli for gas exchange.

For more information: Refer to the unit guide.