LESSON 7: RESPIRATORY SYSTEM LBBBIO7
FIRST TRIMESTER | 2025-2026
○ Respiratory Portion – starts from the respiratory
SYNCHRONOUS SESSION bronchioles to the alveoli.
■ This is where gas exchange occurs.
The Respiratory System
● Elasticity of the Lungs
○ The lungs have elastic fibers that allow for
compliance and expansion during inhalation
● Respiration involves the respiratory tree, which consists of a ○ Oxygen is inhaled, while carbon dioxide is
series of tubes extending from the nasal cavity down to the expelled through the ventilating mechanism.
lungs and the alveoli (air sacs) where gas exchange occurs.
Conducting Portion
Components of the RS
● Ventilating Mechanism
○ Includes the chest (thoracic) wall, diaphragm,
and intercostal muscles. ● Pharynx
○ Responsible for the inhalation and exhalation of ○ Nasopharynx – located behind the nasal cavity.
air. ○ Other parts include the oropharynx and
○ The main respiratory muscles are: laryngopharynx (hypopharynx).
■ Diaphragm ● Larynx
■ Intercostal muscles ○ Guards the entrance to the trachea.
○ These muscles enable the expansion and ○ Air passes from the larynx → trachea → bronchi
contraction of the thoracic cavity for ventilation. → bronchioles → terminal bronchioles.
● Tubes of the Respiratory System ○ Types of bronchi:
○ Divided into two parts: ■ Primary bronchus
■ Conducting Portion – extends from ■ Secondary bronchus
the upper airways down to the ■ Tertiary bronchus
terminal bronchioles.
● No gas exchange occurs Respiratory Portion
here.
● Bridges movement of air
from nasal cavity to terminal
bronchioles
● Functions: humidification,
filtration, and conduction of
air.
LBBBIO7: Histology Laboratory LESSON 7 1
FIRST TRIMESTER | 2025-2026
○ Respiratory Portion – starts from the respiratory
SYNCHRONOUS SESSION bronchioles to the alveoli.
■ This is where gas exchange occurs.
The Respiratory System
● Elasticity of the Lungs
○ The lungs have elastic fibers that allow for
compliance and expansion during inhalation
● Respiration involves the respiratory tree, which consists of a ○ Oxygen is inhaled, while carbon dioxide is
series of tubes extending from the nasal cavity down to the expelled through the ventilating mechanism.
lungs and the alveoli (air sacs) where gas exchange occurs.
Conducting Portion
Components of the RS
● Ventilating Mechanism
○ Includes the chest (thoracic) wall, diaphragm,
and intercostal muscles. ● Pharynx
○ Responsible for the inhalation and exhalation of ○ Nasopharynx – located behind the nasal cavity.
air. ○ Other parts include the oropharynx and
○ The main respiratory muscles are: laryngopharynx (hypopharynx).
■ Diaphragm ● Larynx
■ Intercostal muscles ○ Guards the entrance to the trachea.
○ These muscles enable the expansion and ○ Air passes from the larynx → trachea → bronchi
contraction of the thoracic cavity for ventilation. → bronchioles → terminal bronchioles.
● Tubes of the Respiratory System ○ Types of bronchi:
○ Divided into two parts: ■ Primary bronchus
■ Conducting Portion – extends from ■ Secondary bronchus
the upper airways down to the ■ Tertiary bronchus
terminal bronchioles.
● No gas exchange occurs Respiratory Portion
here.
● Bridges movement of air
from nasal cavity to terminal
bronchioles
● Functions: humidification,
filtration, and conduction of
air.
LBBBIO7: Histology Laboratory LESSON 7 1
