The document discusses the structure and components of the lower respiratory tract, including the trachea, lungs, and bronchi. It describes the trachea as being composed of cartilage rings and having three tissue layers. The lungs are located in the thoracic cavity and each have an apex, base, costal surface, and hilum. Inside the lungs are bronchi and bronchioles that branch into smaller structures ending in alveoli. The pleura surround each lung and form the pleural cavity.

1. Dr. JayeshPatidar
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RESPIRATORY SYSTEM

2. Lower respiratory tract
It includes:
A.Trachea,
B.Lungs,
C.Bronchi.
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3. Respiratory tract
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4. TRACHEA
Structures associated with the trachea:
Superiorly: the larynx.
Inferiorly:the right & left bronchi.
Anteriorly:Isthmus of Thyroid gland & the arch of the aorta & the sternum.
Posteriorly:the esophagus separates the trachea from the vertebral column.
Laterally:the lungs
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5. STRUCTURE OF THE TRACHEA
It is composed of 3 layers of tissues & held by between 16-20 incomplete rings of hyaline cartilage.
Rings are incomplete posteriorly.
Connective tissues & involuntary muscle join the cartilages & form the posterior wall which is in contact with the esophagus.
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6. Three layers of tissue:
I.The outer layer: consists of fibrous & elastic tissue & encloses the cartilages.
II.The middle layer:consists of bands of smooth muscles in a helical manner. There is some areolar tissue.
III.The inner lining:consists of ciliated columnar epithelium, containing mucus secreting Goblet cells.
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7. LUNGS
There are 2 lungs, each lying on each side of the midline in the thoracic cavity.
They have-
oApex,
oBase,
oCostal surface,
oMedial surface-Hilum at 5th, 6th, 7ththoracic vertebrae.
•The area between the lungs: Mediastinum.
•Lobes of the right & left Lungs.
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8. PLEURA & PLEURAL CAVITY:
Pleura consists of a closed sac of serous membrane which contains a small amount of serous fluid.
Each lung is pushed into this sac so that 2 layers are formed:
a.One adherent to the lungs -visceral
b.Another adherent to the wall of the thoracic cavity-parietal
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9. Inside the lungs..
Bronchi & bronchioles:
Two primary bronchi are formed when trachea divides at the level of 5ththoracic vertebra.
The right bronchus:
-wider, shorter & more vertical than the left one.
-Approx 2.5 cm
The left bronchus:
-About 5cm long
-Narrower.
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10. BRONCHIAL TREE
The bronchi divide as follows:
Bronchi bronchioles terminal bronchioles
respiratory bronchioles alveolar ducts
alveoli. s
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11. Thank you
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