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Structures and Functions
Respiratory System Structures and Functions
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Parts of Respiratory System
Nasal Cavity Pharynx Larynx Trachea Bronchi Bronchioles Alveoli Lungs Pleura
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Functions of the Respiratory System
Provides oxygen for the body and removes carbon dioxoide through respiration Production of sound
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Respiratory System Body has an average oxygen reserve to last about 4 –6 minutes If reserve is not replenished , death is the outcome
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Respiratory Tract Upper Respiratory Tract Nose Pharynx Larynx
Lower Respiratory Tract Trachea All segments of the bronchial tree Lung
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Nasal Cavity Air enters body through nostrils (anterior nares)
Inside the nostrils, are 2 spaces known as nasal cavities Nasal cavities are lined with mucous membranes
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Nasal Cavity Nasal Septum—divides nasal cavities into right and left sides Three turbinates or bones that protrude into the nasal cavity—they increase surface area for filtering dust and dirt Cilia—the hairs in your nose that trap larger dirt particles
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Changes To The Air As It Comes In Contact With the Lining of the Nose
Foreign bodies filtered out by cilia and mucous membrane Air is warmed Air is moistened
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Effect of Smoking on Cilia
Cigarette smoke paralyzes the cilia and results in accumulations of mucus and the typical smoker’s cough, which is an effort to clear the secretions
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Sense of Smell Originates in your nose!
Olfactory nerves (which provide the sense of smell) are located in the mucus membrane.
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Sinuses Cavities in skull Ducts connect sinuses to nasal cavity
Named: frontal, maxillary, sphenoid, and ethmoid Give resonance to voice (nasal sound when you have a cold due to blockage or sinuses)
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Pharynx The throat Common passageway for air and food 5 inches long
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Pharynx When food is swallowed, the EPIGLOTTIS closes over the opening to the larynx, preventing food from entering the lungs Eustachian tube connect the middle ear to the nasopharynx
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Larynx The voice box Triangular chamber below pharynx
Within the larynx are vocal cords (GLOTTIS) It is composed of several pieces of cartilages – the largest is the Adams’s Apple
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Trachea Windpipe 41/2 inches long
Walls are bands of C-shaped rings of cartilage—to keep trachea open Lined with ciliated mucous membrane Coughing and expectoration gets rid of dust-laden mucous
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Bronchi and Bronchioles
Bronchial tubes have cartilaginous plates instead of rings Bronchial tubes lead to even smaller bronchioles Bronchioles—thinner walls of smooth muscle At the end of the bronchiole is the alveoli Lower end of trachea divides into right and left bronchus Bronchi—similar to trachea with ciliated mucous and rings of cartilage As they enter lungs divide into smaller bronchial tubes
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Bronchi, Bronchial Tubes and Bronchioles
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Alveoli Composed of single layer of epithelial tissue
Inner surfaces covered with SURFACTANT (keeps alveoli from collapsing) Each alveolus is surrounded by capillaries Oxygen and carbon dioxide exchange takes place between alveoli and capillaries
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Lungs Fill thoracic cavity Upper part—apex Lower part—base
Lung tissue is porous and spongy—it floats Right lung—larger and shorter (displaced by liver) Has 3 lobes Left lung—smaller (displaced by heart) Has two lobes
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Pleura Thin, moist, slippery membrane that covers lungs
Double-walled sac Space is pleural cavity—filled with pleural fluid to prevent friction
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Pulmonary Ventilation (Breathing)
Inspiration Intercostal muscles lift ribs outward Sternum rises Diaphragm contracts and moves downward This increases the volume of the lungs and air rushes in Expiration (exhalation) Opposite action takes place Exhalation is a passive process
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Breathing Process
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Respiratory Movements
1 inspiration + 1 expiration = 1 respiration Respiratory rate for normal adult is 14-20
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Factors that Affect Respiratory Rate
Increases with exercise, fever, certain diseases Age—newborn = per minute Sleep—respirations decrease Emotion can increase or decrease
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Coughing Deep breath followed by forceful expulsion of air—to clear lower respiratory tract
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Hiccups Spasm of the diaphragm and spasmotic closure of the glottis
Caused by irritation to diaphragm or phrenic nerve
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Sneezing Air forced through nose to clear respiratory tract
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Yawning Deep prolonged breath that fills the lungs and increases oxygen within the blood
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Control of Breathing Then the phrenic nerve stimulates the diaphragm
Chemical Factors Depends on levels of carbon dioxide in blood Chemoreceptors in aorta and carotid arteries are sensitive to the amount of oxygen in blood Controlled by neural and chemical factors Neural Factors Respiratory center in medulla oblongota Increase in carbon dioxide or decrease in oxygen will trigger respiratory center
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