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BY
DR. MUDASSAR ALI ROOMIDR. MUDASSAR ALI ROOMI
(MBBS, M. PHIL.)
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The olfactory epithelium has:
(a) Columnar epithelium with goblet cella
(b) columnar stratified epithelium
(c) bipolar neurons(d) Clara cells
(e) Dust cells
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The respiratory epithelium of the conducting
portion of the respiratory tract has:
(a) stratified squamous epithelium
(b) pseudostratified columnar
epithelium(c) No ciliated cells
(d) No goblet cells
(e) Cells with stereocilia
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PHARYNX
The pharynx connects the nasal cavity with thelarynx.
Depending on the extent of abrasive forces on theepithelium, the pharynx is either lined withrespiratory epithelium ( in nasopharynx) or with astratified squamous epithelium (in oropharynx andhypopharynx)
Lymphocytes frequently accumulate beneath theepithelium of the pharynx (pharyngeal tonsils).
The nasal cavity and pharynx form the upper respiratory passages.
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LARYNX
The larynx connects the pharynx and trachea.
The vocal folds of the larynx control airflowand allow the production of sound.
The true vocal folds are lined by stratifiedsquamous non-keratinized epithelium(MCQ)and contain the muscle (striated, skeletal) andligaments.
Respiratory epithelium lines the false vocalfold, as in posterior epiglottis.
The larynx is supported by a set of cartilages.
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LARYNX
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EPIGLOTTIS
The epiglottis is the superior portion of the larynx that projects
upward from the larynx¶s anterior wall. It has both a lingual and alaryngeal surface.
A central elastic cartilage of epiglottis forms the framework of
the epiglottis.
Its lingual mucosa ( anterior side) is lined with a stratified
squamous nonkeratinized epithelium . The lingual mucosa with its stratified squamous epithelium covers
the apex of the epiglottis and about half of the laryngeal mucosa
(posterior side).
Toward the base of the epiglottis on the laryngeal surface , the
lining stratified squamous epithelium changes to pseudostratifiedciliated columnar epithelium.
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Located below the epithelium in the lamina
propria on the laryngeal side of the epiglottis
are tubuloacinar seromucous glands.
In addition to the tongue, taste buds and solitarylymphatic nodules may be observed in the
lingual epithelium or laryngeal epithelium
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Trachea
1. Mucosa:
it is lined with Pseudostratified columnar,ciliated epithelium with goblet cells (respiratory
epithelium).2. Submucosa: it contains Sero-mucous glands
3. 16-20 C-shaped rings of hyaline Cartilage +trachialis muscle
4. adventitia: it has loose connective tissue
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Bronchi
Extrapulmonary bronchus is just like thetrachea.
Intrapulmonary bronchi have got thefollowing differences from the
extrapulmonary bronchi:1. Pseudostratified columnar, ciliated epithelium
(shorter) Goblet cells (fewer)
2. Irregular Cartilage plates all around the wall
3. Smooth muscle layer is complete
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Cancer of lung (bronchogenic
carcinoma)
Smoking is a major reason
Pseudostratified epithelium changes to
stratified squamous epithelium
(squamous metaplasia)
Dysplasia leads to cancer
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Bronchioles
1 mm or less in diameter.
Simple columnar or cuboidal ciliated
epithelium goblet cells present in larger bronchioles
but absent in the smaller ones.
No cartilage in their walls
Mucosa contains no glands.
Smooth muscle (relatively abundant)
Clara cells (non ciliated cells): producesurfactant and function as stem cells.
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Respiratory Bronchiole
Simple cuboidal, ciliated epithelium
Goblet cells and glands are entirelyabsent.
Clara cells are present here.
Alveolar outpocketing on its walls.
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Cystic fibrosis
Cystic fibrosis: it is due to abnormal Cl-
transport by Clara cells
Associated with thick mucus and
recurrent lung infections.
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asthma
Recurrent spasm of bronchiolar smooth
muscles.
It is a type of hypersensitivity reaction.
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Alveoli
Type I alveolar cells or type 1 Pneumocytes (squamous
alveolar cells):
flattened for gas exchange
40% of all cells in the wall of alveoli but cover 90-95% of the surface area.
With capillary endothelium, form the thin blood-air
barrier (0.6 um thick).
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Type II alveolar cells or type 2 Pneumocytes (great
alveolar cells):
cuboidal in shape
60% of all cells in the wall of alveoli but cover 5-10% of the surface area.
Luminal surface of these cells bear microvilli
Are secretory cells and produces surfactant
Contain numerous secretory granules
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Alveolar Macrophages (dust cells)
Are monocytes that enter pulmonary
connective tissue and alveoli
are somponent of reticuloendothelial
system
Clean alveoli of invading organisms and
phagocytose particular matter
Their cytoplasm is laiden withphagocytosed carbon and dust pariticles.
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emphysema
Destruction of
alveolar walls.
Large air spaces.
wasted ventilation.
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The type I alveolar cells:
(a) are columnar epithelial cells
(b) are rounded or cuboid in shape
(c) have abundant microvilli on their surface
(d) secrete surfactant
(e) are involved in gaseous exchange
with the blood
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Respiratory surfactant:
(a) is secreted by type II (great alveolar)
cells
(b) increases surface tension of alveoli
(c) Has nothing to do with surface tension
of alveoli
(d) Not essential for correct respiratory
function
(e) mainly a triglyceride
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The alveolar dust cells:
(a) are phagocytic
(b) secrete surfactant
(c) produce antibodies(d) Are mast cells
(e) develop from eosinophils