Page 191 - Physiology and Pathophysiology MNU 2024-2025 نظرى

Clinical pharmacy 2024/2025 Level 2 Pharm D Physiology and Pathophysiology (MD303)

Epithelium The pleura

 All the conducting airways are lined Double-walled sac encloses each lung.

with ciliated epithelium with some The visceral pleura parietal The pleural space
mucus-secreting cells. pleura

 The cilia beat upward at frequencies membrane lines the space in between

600-900 beats/minute  continuously adhered to the walls of the the two layers 

move the mucus away from the external surface of thoracic filled with pleural
respiratory zone toward the pharynx the lungs cavity. fluid:

 removes inhaled particles from the
a. Lubricates the membranes   friction between the
lungs.
layers.

b. Maintain lung inflation keeps the 2 layers of the pleura
The nicotine found in cigarette smoke 
“adhered” to each other  the lungs are in contact with
paralyzes the cilia  impairing their
the thoracic wall  fill the thoracic cavity, and remain
ability to remove any toxic substances.
inflated.

Mechanics of breathing

Air will move from an area of high pressure to an area of low pressure.

Thoracic volume

The volume of the thoracic cavity increases during inspiration and decreases during expiration.

1- Inspiration
The most important muscles of inspiration:

 Supplied by the phrenic nerves.

 When contracts  flattens & pushes downward   the vertical dimension
Diaphragm
of the thoracic cavity   thoracic volume. (Responsible for 75% of the
enlargement of the thoracic cavity)

| P a g e 125