A. Primary function
Provide oxygen for the metabolism in the tissue
Remove carbon dioxide, the waste product of metabolism

B. Secondary functions

1. Facilitates the sense of smell.
2. Produces speech
3. Maintain acid base balance
4. Maintain body water levels
5. Maintain body heat balance

C. Upper respiratory track
1. Nose: Humidifies ,Warm ,and filters inspired air
2. Sinuses: Air filled cavities within the hollow bones that surround the nasal passage
Provide resonance during speech.
3. Pharynx
.Located behind the oral and nasal cavity
.divided to
.passage way of both respiratory and digestive track
4. Larynx
.Located above the trachea and just below the pharynx at the root of the tongue
.Commonly called voice box
.Contain two pair of vocal cords, the false and true cords
.The opening between the true vocal cords is the GLOTTIS
.The glottis plays an important role in coughing. This is the fundamental defense mechanism of the Lungs

5. Epiglottis
.Leaf-shaped elastic structure that is attached along one end to the top of the larynx
.IT prevent food from entering the tracheo-bronchial tree by closing over the glottis during swallowing

D. Lower respiratory track.
1. Trachea
a. Located in front of the esophagus
b. Branches in to right and left main stem bronchi at the carina.

2. Mainstem bronchi
a. Begin at the carina.
b. The right bronchus is slightly wider, shorter, and more vertical than the left bronchus
c. Mainstem bronchi is divided in to five lobar bronchi that enter each of the five lobes of the lung
d. Bronchi are lined with cilia, which propel mucus up and away from the lower air way to the trachea, where it can be expectorated or swallowed

3. Bronchioles.
a. Branches from the lobar bronchi and sub divided in to the small terminal and respiratory bronchioles
b. They contain no cartilage. And depend on the elastic recoil of the lung for the patency.
c. They contain no cilia. And do not participate in gas exchange.

4. Alveolar duct and alveoli.
a. Acinus is a term used to indicate all the structure distal to the terminal bronchiole.
b. Alveolar ducts branches from the respiratory bronchioles.
c. Cells in the wall of the alveoli secrete surfactant, a phospholipid protein that reduces the surface tension in the alveoli; without surfactant, the alveoli will collapse.

5. Lung
a. Located in the pleural cavity in the thorax
b. Extend from just above the clavicles to the diaphragm, the major muscle of inspiration.
c. The right lung. Larger than the left lung. It is divided in to 3 lobes, upper, middle, and the lower lobe.
d. The left lung, is somewhat narrower than the right lung to accommodate the heart, it is divided in to 2 lobes
e. Innervation of the respiratory structure is accomplished by the phrenic nerve, the vagus nerve, and the thoracic nerve.
f. The parietal pleura line the inside of the thoracic cavity, including the upper surface of the diaphragm.
g. The visceral pleura covers the pulmonary surfaces
h. A thin fluid layer which is produced by the cells lining the pleura, lubricates the visceral pleura and the parietal pleura, allowing them to glide smoothly and painlessly during respiration
i. Blood flow to the lung occurs via the pulmonary system and the bronchial system

6. Accessory muscles of respiration
a. Scalene muscle, which elevate the first two ribs
b. Sternocleidomastoid muscles, which raise the sternum
c. Trapezius and pectoralis muscles, which fix the shoulder

7. The respiratory process
a. The diaphragm descend into the abdominal cavity during inspiration, causing negative pressure in the lunge
b. The negative pressure draws air from the area of greater pressure, the atmosphere, into the area of lesser pressure, the lungs.
c. In the lungs, air passes through the terminal bronchioles into the alveoli to oxygenate the body tissue.
d. At the end of inspiration, the diaphragm and the intercostal muscle are relaxed and the lung recoil.
e. As the lungs recoil, pressure within the lungs becomes greater than atmospheric pressure, causing the air, which now contain the cellular waste products of carbon dioxide and water, to move from the alveoli in the lungs to the atmosphere
Risk factor for respiratory disease
Chewing tobacco.
Frequent respiratory illness.
Chest injury.
Exposure to chemical and environmental pollution.
Crowded living condition.
Family history of infectious disease.
Geographic residence and travel to foreign countries
A. Lungs sound
Normal Lungs sound
Abnormal lungs sound
#Normal lung sound : Bronchial LS
Bronchio-vesiular LS
Vesicular LS
Bronchial LS: heard over trachea and larynx. Loud, hard, high pitched sound. Heard when the air passes through large airway. Usually heard at 1st and 2nd intercostal space. Expiration phase is longer than inspiration.

Bronchio-vesiular LS: Heard near to the main stem bronchi. Moderately pitched breezy sound. Heard when air passes through smaller air way like lobar bronchi and bronchioles, Heard at 3rd intercostal space. Inspiration and expiration phase is equal

Vesicular LS: heard over entire lung. Heard when air is moved in and out of the alveolar. Low pitched and quite sound. Heard over 4th intercostal space. Inspiration phase is longer than expiration.

Abnormal lung sound
.Fine crackles
.coarse crackles
.Sibilant wheezing
.sonorous wheezing
.plural frication rub

Fine crackles: Short, high pitched bubbling sound. Heard during inspiration. Heard due to the presence of fluid or mucous.

Coarse crackles: Short Low pitched bubbling sound. Heard during inspiration and expiration. Heard due to the presence of pneumonia or air collection.

Sibilant wheezing: High pitched musical sound. Heard during inspiration.

Sonorous wheezing: low pitched rumbling sound. Heard during expiration. Heard due to bronchial asthma foreign body obstruction or tumor.

Plural frication rub; It is a greeting or cracking sound. Heard during inspiration. Eg:-.Pluresy
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