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Respiratory System
Oversees gas exchange
between blood and external
environment
Anatomy of Respiratory System
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Nose
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Pharynx (throat)
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Ciliated mucosa propel debris
away from lungs
Bronchi
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Thyroid (Adams apple)
Epiglottis (closes when swallow)
Trachea (windpipe)
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Muscular passageway
Tonsils – lymphatic system
Larynx (voice box)
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Purify, humidify, and warms (by
veins) incoming air
Cilia propel mucus to pharynx
Sinuses – lighten skull, act as
resonance chamber for speech
Subdivisions (bronchioles) branch
off and enter lungs
Lungs
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R. lung 3 lobes, L. lung 2 lobes
Pleura – surface lining
Alveoli – air sacs at terminal ends
Alveoli: Site of gas exchange
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Alveoli
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Simple squamous epithelial
tissue
Covered in a cobweb of
pulmonary capillaries
Macrophages move
in/out of alveoli
Cuboidal cells secrete
surfactant
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lipid coats alveoli
Prevents alveoli collapse
Begins to function at 28-30
weeks during gestation
Respiration Physiology
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Pulmonary Ventilation
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External Respiration
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Gas exchange between blood and alveoli
Respiratory Gas Transport
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Continuously refreshing the air in the lungs
O2 & CO2 transported via blood
Internal Respiration
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Gas exchange between blood and tissues
Mechanics of Breathing
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Inspiration
 Diaphragm and external
intercostals muscles contracts
 Size of thoracic cavity increases,
lung volume increases (lung
pressure decreases below atm
pressure) and creates a partial
vacuum
 Air enters lungs
Expiration
 Inspiratory muscles relax,
resuming initial size
 Lungs recoil (effortless)
 Air is exhaled
Respiratory Volumes and Capacities
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Spirometer – measures respiratory
capacities
Vital Capacity
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Tidal Volume
 Normal quiet breathing (500mL
ea/breath)
Inspiratory Reserve Volume
 Air taken in forcibly (21003200mL over TV)
Expiratory Reserve Volume
 Air forcibly expelled (1200mL)
Residual Volume
 Air remaining in lungs that
cannot be expelled (1200mL)
 Allows gas exchange between
breaths, keeps alveoli inflated
Dead Space Volume
 Air remains in “passageways”
and never reaches alveoli
(150mL)
Control of Respiration
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Neural Regulation
 Nerve impulses from medulla and pons
 Maintain a rate of 12-15 breaths/minute
Other Influential Factors
 Physical Factors
 Talking, coughing, exercising, increase
body temp
 Conscious Control
 Singing, swallowing, swimming
 Limited/ignored if O2 levels get low or CO2
levels get too high
 Emotional
 Hypothalamus reflex (scared, gasp, etc)
 Chemical
 Levels CO2 and decreased blood pH
Interesting Respiratory Topics
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Smoking and its effect on respiratory system
Cleft Palate
Rhinitis (Cold) & Sinusitis
Atelectasis (lung collapse)
Hypoxia (inadequate O2)
Hyperventilation & Hypoventilation
Apnea
Cyanosis
COPD (chronic obstructive pulmonary disease)
Cystic Fibrosis
SIDS (sudden infant death syndrome)
Asthma
Bronchitis & pneumonia
Tuberculosis