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RespiratorySystem

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Structure

Consists of:

Lungs

Conducting part

Respiratory part

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Functions

It serves the following functions:

Conduit of air

Gas exchange

Endocrine function

Acid-base balance

Phonation

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Respiratory Epithelium

Most of the respiratory system is linedby typicalrespiratoryepithelium:

1. Cilaiated columnar epithelium

2. Mucus goblet cells

3. Brush cells

4. Basal cells

5. Granular cells

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Nasal cavity

Consists of

Vestibule:

sweat glands, sebaceous glands, vibrissae

Nasal fossa:

Conchae gives ribbon-like passage

Swell bodies

Complex vascular organization

Olfactory epithelium:

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Trachea

Lined by typical respiratory epithelium

Contains 16-18 c-shaped cartilages

Fibroelastic band bridges the open ends of c-

shaped cartilages

Smooth muscle fibers (Trachialis) also foundin the same place

Numerous seromucus glands

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Bronchus

It is 5 mm or more in diameter

Lined by respiratory epithelium

Plates of cartilage in lamina propria

Smooth muscle layer

Elastic fibers

Seromucus glands

Lymphocytes and

lymphatic nodules

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Bronchiole

They are

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Alveolar Duct

When respiratory bronchiole is totally replaceby alveolar openings

Each alveolar duct opens into atria

Each atrium opens into two or more alveoli

Complex network of elastic and reticular fiberssurrounding the opening of atria, sacs andalveoli

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Alveoli

They are sac like evagination of respiratory

bronchiole, alveolar duct, alveolar sac It is 200 mm in diameter

Alveolar wall

Interalveolar septum Type I cells (Squamous alveolar)

Type II cells

Lung macrophage Air-blood barrier

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