Transcript Chapter 16 The Respiratory System UPPER RESPIRATORY TRACT

Chapter 16
The Respiratory System
UPPER RESPIRATORY TRACT
Nose
• Nasal septum
• Nares
• Frontal, maxillary, sphenoidal, and
ethmoidal sinuses drain into nose
• Warms and moistens inhaled air
• Contains sense organs of smell
Pharynx
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aka throat
3 sections
Plays a role with respiration and digestion
Passageway for food and liquids
Passageway for air
Larynx
• Cartilage forms framework
• Thyroid cartilage (Adam’s apple) is largest
• Epiglottis partially covers opening into larynx
• Vocal cords stretch across interior of
larynx
• Passageway for air to move to and from
lungs
• Voice production
LOWER RESPIRATORY TRACT
Trachea (Windpipe)
• Extends from larynx to thoracic cavity
• C-shaped rings of cartilage hold trachea
open
• Provides passageway for air to move to
and from lungs
Right and Left Bronchi
Bronchioles
Alveoli
• Microscopic sacs
• Surrounded by capillaries
• Exchange gases between blood and lungs
Respiratory Mucosa
• Specialized membrane that lines respiratory tree
• Serves as a filter by trapping inspired irritants
such as dust and pollen
• Upward movement of cilia helps remove trapped
irritants
Lungs
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Apex—narrow upper part
Base—broad lower part
Right larger than left
Divided into lobes
– Right upper, middle, lower
– Left upper, lower
• Function: pulmonary ventilation
Pleura
• Moist membrane that lines chest cavity
and covers outer surface of lungs
• Reduces friction
MECHANICS OF BREATHING
Respiration
• Two phases
– inspiration
– expiration (movement of air out of lungs)
• Changes in air pressure cause air to move
into and out of the lungs
Inspiration
• Active process
• Diaphragm and external intercostals
contract
• Thoracic cavity enlarges
• Pressure in thoracic cavity is less than that
of the atmosphere
• Air rushes in
Expiration
• Ordinarily a passive process
• Diaphragm and external intercostals relax
• Pressure in thoracic cavity greater than
that of the atmosphere
• Air is “pushed” out of lungs by pressure
Gas Exchange
• Carbon dioxide moves out blood into
alveoli and out of body in expired air
• Oxygen moves from alveoli into blood
Volumes
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Measured with a spirometer
Tidal volume (TV)— normally breath
Vital capacity (VC)—forced expiration
Expiratory reserve volume (ERV)—
what is left after forced expiration
• Inspiratory reserve volume (IRV)—
forcibly inhaled after a normal inspiration
• Residual volume (RV)—
air that remains in the lungs after the most
forceful expiration
Respiratory Rate
Usually about 12 to 18
breaths/minute
Regulation of Respiration
Located in respiratory center of
the medulla oblongata