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Chapter 30

Respiratory System

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Respiration• Ventilation: Movement of air into and out

of lungs• External respiration: Gas exchange

between air in lungs and blood• Transport of oxygen and carbon dioxide in

the blood• Internal respiration: Gas exchange between

the blood and tissues

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Respiratory System Functions • Gas exchange: Oxygen enters blood and carbon

dioxide leaves• Regulation of blood pH: Altered by changing

blood carbon dioxide levels• Voice production: Movement of air past vocal

folds makes sound and speech• Olfaction: Smell occurs when airborne

molecules drawn into nasal cavity• Protection: Against microorganisms by

preventing entry and removing them

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Respiratory System Divisions• Upper tract

–Nose, pharynx and associated structures

• Lower tract–Larynx,

trachea, bronchi, lungs

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Nose and Pharynx• Nose–External nose–Nasal cavity

• Functions–Passageway for air–Cleans the air–Humidifies, warms air–Smell–Along with paranasal

sinuses are resonating chambers for speech

• Pharynx–Common opening

for digestive and respiratory systems

–Three regions• Nasopharynx• Oropharynx• Laryngopharynx

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Larynx

• Functions–Maintain an open passageway for air

movement–Epiglottis and vestibular folds prevent

swallowed material from moving into larynx

–Vocal folds are primary source of sound production

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Vocal Folds

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Trachea

• Windpipe• Divides to

form–Primary

bronchi

Insert Fig 23.5 all but b

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Tracheobronchial Tree• Conducting zone

–Trachea to terminal bronchioles which is ciliated for removal of debris

–Passageway for air movement–Cartilage holds tube system open and

smooth muscle controls tube diameter• Respiratory zone

–Respiratory bronchioles to alveoli–Site for gas exchange

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Tracheobronchial Tree

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Bronchioles and Alveoli

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Lungs• Two lungs: Principal

organs of respiration–Right lung: Three lobes–Left lung: Two lobes

• Divisions–Lobes,

bronchopulmonary segments, lobules

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Ventilation• Movement of air into and out of

lungs• Air moves from area of higher

pressure to area of lower pressure• Pressure is inversely related to

volume

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Alveolar Pressure Changes

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Changing Alveolar Volume• Lung recoil

– Causes alveoli to collapse resulting from • Elastic recoil and surface tension

– Surfactant: Reduces tendency of lungs to collapse

• Pleural pressure– Negative pressure can cause alveoli to expand– Pneumothorax is an opening between pleural

cavity and air that causes a loss of pleural pressure