Transcript Chapter 16 The Respiratory System

Chapter 16
The Respiratory System
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Structural Plan
• Basic plan of respiratory system would
be similar to an inverted tree if it were
hollow; leaves of the tree would be
comparable to alveoli, with the
microscopic sacs enclosed by networks
of capillaries
• Diffusion is how gas exchange occurs
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Respiratory Tracts
• Upper respiratory tract—nose, pharynx,
and larynx
• Lower respiratory tract—trachea,
bronchial tree, and lungs
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Respiratory Mucosa
• Mucous membrane
• ½ cup of mucus produced each day
• Mucus air purification by trapping inspired
irritants such as dust, pollen
• Cilia on cells beat in one direction, moving
mucus upward to pharynx for removal
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Nose
• Functions
– Warms and moistens inhaled air
– Contains sense organs of smell
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Larynx
• Structure
– The voice box
• Thyroid cartilage (Adam’s apple)
• Epiglottis partially covers opening into larynx
– Vocal cords stretch across interior of
larynx; space between cords is the glottis
– Mal Webb's Larynx in Hamburg
– http://www.youtube.com/watch?v=Q-PZlj0UH0c
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Disorders of the
Upper Respiratory Tract
• Upper respiratory infection
– Laryngitis—inflammation of the larynx
resulting from infection or irritation
• Epiglottis—life threatening
• Croup—not life threatening
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Trachea
• Structure
– 11 cm (4½ inches) long extends from larynx
into the thoracic cavity
– Mucous lining
– C-shaped rings of cartilage hold trachea open
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Bronchi,
Bronchioles, and Alveoli
• Respiratory distress—inability to inflate alveoli
– Infant respiratory distress syndrome (IRDS)—
leading cause of death in premature infants from
lack of surfactant production in alveoli
– The second son of President John F. Kennedy,
Patrick B. Kennedy died from respiratory distress
syndrome (RDS) when he was only two days old, on
August 9, 1963.
He was born 5 1/2 weeks prematurely on August 7,
1963.
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Lungs and Pleura
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•
•
•
Function—breathing (pulmonary ventilation)
Pleurisy—inflammation of the pleura
Atelectasis—collapse of lung (alveoli);
can be caused by:
– Pneumothorax—air in pleural space
– Hemothorax—blood in pleural space
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Respiration
• Mechanics of breathing
– Two phases called inspiration (movement of air
into lungs) and expiration (out of lungs)
– Changes in size and shape of thorax cause
changes in air pressure within that cavity and in
the lungs because as volume changes
– Air moves into or out of lungs because of pressure
differences (pressure gradient)
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Respiration
• Exchange of gases in lungs
– Carbaminohemoglobin breaks down into carbon
dioxide and hemoglobin
– Oxygen & Carbon dioxide moves due to?
– Hemoglobin combines with oxygen, producing
oxyhemoglobin
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Respiration
• Exchange of gases in tissues
– Oxyhemoglobin breaks down into oxygen
and hemoglobin
– Oxygen & Carbon dioxide moves ?
– Hemoglobin combines with carbon dioxide,
forming carbaminohemoglobin
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Blood Transportation of Gases
• Transport of oxygen
– Only small amount of O2 can be dissolved in
plasma
– Most O2 combines with hemoglobin to form
oxyhemoglobin to be carried in blood
• Transport of carbon dioxide
– Dissolved carbon dioxide—10%
– Carbaminohemoglobin—20%
– Bicarbonate ions—70%
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Blood Transportation of Gases
• Volumes of air exchanged
– Tidal volume (TV)—amount normally breathed in
or out with each breath
– Vital capacity (VC)—largest amount of air that one
can breathe out in one expiration
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Regulation of Respiration
• Regulation permits body to adjust to varying
demands for O2 supply and CO2 removal
• Brainstem respiratory control centers
(inspiratory and expiratory centers)
– Medullary centers—under resting conditions these
centers in the medulla produce a normal rate and
depth of respirations (12 to 18 per minute)
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Regulation of Respiration
• Cerebral cortex—voluntary (but limited)
control of respiratory activity
• Receptors influencing respiration
– Chemoreceptors—respond to changes in
CO2, O2, and blood acid levels
– Pulmonary stretch receptors—protect
respiratory organs from overinflation
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Types of Breathing
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•
•
•
•
Eupnea—normal breathing
Hyperventilation—rapid, deep
Hypoventilation—slow, shallow
Dyspnea—labored or difficult
Apnea—stopped breathing
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Disorders of the
Lower Respiratory Tract
• Tuberculosis (TB)—chronic, highly
contagious lung infection characterized
by tubercles in the lung; can progress to
involve tissues outside the lungs and
pleurae
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Disorders of the
Lower Respiratory Tract
• Restrictive pulmonary disorders reduce
the ability of lung tissues to stretch (as
during inspiration)
– Factors inside the lungs, such as fibrosis
(scarring) or inflammation, may restrict
breathing
– Factors outside the lungs, such as pain
from injury or pleurisy, may restrict
breathing
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Disorders of the
Lower Respiratory Tract
• Obstructive pulmonary disorders
– Obstruct breathing
– Chronic obstructive pulmonary disease (COPD)
can develop from preexisting obstructive
conditions
• Chronic bronchitis—chronic inflammation of the bronchial
tree
• Emphysema—reduced surface area of lungs caused by
rupture or other damage to alveoli
• Asthma—recurring spasms of the airways accompanied
by edema and mucus production
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