C.A.B.M. | 2024
1
The Respiratory System
Overview
The respiratory system facilitates the exchange of gases
(oxygen and carbon dioxide) between the blood and the
environment. The major functions include supplying the
body with oxygen and disposing of carbon dioxide. Key
events in respiration are pulmonary ventilation, external
respiration, respiratory gas transport, and internal
respiration.
Organs of the Respiratory System
• Nose
• Pharynx
• Larynx
• Trachea
• Bronchi
• Lungs (alveoli)
Functional Anatomy
• Gas exchange occurs only in the alveoli.
• Upper respiratory tract: Includes passageways
from the nose to the larynx.
• Lower respiratory tract: Includes passageways
from the trachea to the alveoli.
• Passageways purify, humidify, and warm
incoming air.
The Nose
• Externally visible and serves as the entry point
for air.
• Nostrils (nares) lead air into the nasal cavity,
which is divided by the nasal septum.
• Olfactory receptors located in the superior
mucosa detect smells.
• Respiratory mucosa:
o Moistens air.
o Traps incoming foreign particles.
o Contains enzymes to destroy bacteria.
• Nasal conchae:
o Projections increase surface area and air
turbulence.
o Aid in trapping inhaled particles.
• Palate separates the nasal cavity from the oral
cavity:
o Hard palate (anterior, bony support).
o Soft palate (posterior, unsupported).
• Paranasal sinuses:
o Found in frontal, sphenoid, ethmoid, and
maxillary bones.
o Functions:
▪ Lighten the skull.
▪ Act as resonance chambers for
speech.
▪ Produce mucus.
The Pharynx
• Commonly called the throat; muscular
passageway from the nasal cavity to the larynx.
• Three regions:
1. Nasopharynx (superior, behind the
nasal cavity); opened by
pharyngotympanic tubes, draining the
middle ear
2. Oropharynx (middle, behind the
mouth).
3. Laryngopharynx (inferior, attached to
the larynx).
• Functions:
o Passageway for food and air.
