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Region Support Glands Epithelium Cell Types Additional Features

Extrapulmonary Conducting Division

Nasal vestibule Hyaline cartilage Sebaceous andsweat glands

Stratified squamouskeratinized

Epidermal Vibrissae

Nasal cavity:respiratory Hyaline cartilageand bone Seromucousglands Respiratory Basal, goblet, ciliated,brush, serous, andDNES

Erectile-like tissue

Nasal cavity:olfactory

Bone Bowman'sglands (serous)

Olfactory Olfactory,sustentacular, andbasal

Olfactory vesicle

Nasopharynx Skeletal muscle Seromucousglands

Respiratory Basal, goblet, ciliated,brush, serous, andDNES

Pharyngeal tonsils andeustachian tubes

Larynx Hyaline and elastic

cartilages

Mucous and

seromucousglands

Respiratory

stratified squamousnonkeratinized

Basal, goblet, ciliated,

brush, serous, andDNES

Epiglottis, vocal folds,

and vestibular folds

Trachea andprimary bronchi

Hyaline cartilageand dense, irregular,collagenous,connective tissue

Mucous andseromucousglands

Respiratory Basal, goblet, ciliated,brush, serous, andDNES

C-rings and trachealismuscle (smooth muscle)in adventitia

Intrapulmonary Conducting Division

Secondary(intrapulmonary)

bronchi

Hyaline cartilageand smooth muscle

Seromucousglands

Respiratory Basal, goblet, ciliated,brush, serous, and

DNES

Plates of hyalinecartilage and two ribbons

of helically orientedsmooth muscle

(Primary)bronchioles

Smooth muscle No glands Simple columnar tosimple cuboidal

Ciliated cells andClara cells (andoccasional goblet cellsin larger bronchioles)

Less than 1 mm indiameter; supply air tolobules; two ribbons ofhelically oriented smoothmuscle

Terminalbronchioles

Smooth muscle No glands Simple cuboidal Some ciliated cellsand many Clara cells(no goblet cells)

Less than 0.5 mm indiameter; supply air tolung acini; some smooth

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muscle

Respiratory Division

Respiratorybronchioles

Some smoothmuscle and collagenfibers

No glands Simple cuboidal andhighly attenuatedsimple squamous

Some ciliated cuboidalcells, Clara cells, andtypes I and IIpneumocytes

Alveoli in walls; alveolihave smooth musclesphincters in theiropenings

Alveolar ducts Type III collagen(reticular) fibers andsmooth musclesphincters of alveoli

No glands Highly attenuatedsimple squamous

Type I and type IIpneumocytes ofalveoli

No walls of their own;only a linear sequence ofalveoli

Alveolar sacs Type III collagenand elastic fibers

No glands Highly attenuatedsimple squamous

Type I and type IIpneumocytes

Clusters of alveoli

Alveoli Type III collagenand elastic fibers

No glands Highly attenuatedsimple squamous

Type I and type IIpneumocytes

200 m in diameter;have alveolar

macrophages