dr. nabil khouri md, msc. ph - · pdf filevibrissae – skin - sebaceous + ... goblet...
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Dr. Nabil Khouri MD, MSc. Ph.D
Respiratory system
Lung
Conducting portion
INTRAPULMONARY
BRONCHI
BRONCHIOLES
TERMINAL
BRONCHIOLES
Respiratory portion
RESPIRATORY
BRONCHIOLES
ALVEOLAR DUCTS
ALVEOLI
Airways – conducting
portion
Nasal cavity
Pharynx (naso – oro –
laringo-)
Larynx
Trachea
Bronchi (extra
pulmonary)
Conducting portion
Nasal Cavity
Nasal cavity composed of three
regions( vestibule, respiratory
and olfactory regions)
Anterior portion – Vestibule:
vibrissae – skin - sebaceous +
sweat glands
Posterior aspect – nasal fossae:
conchae (sup, mid, inf), olfactory
region,
arterial plexuses and venous sinuses
bleeding
Vestibule
Anterior portion of nasal cavity near of the
nares dilated and known as the vestibule
lined with skin and has short, stiff hairs named VIBRISSAE that prevent large dust particles to enter
It is made of Keratinized stratified squamous epithelium
And Non Keratinized stratified squamous epithelium
Dermis houses numerous sebaceous glands
Posterior aspect of Nasal cavity
Is lined by Pseudostratified ciliated columnar epithelium
(RESPIRATORY EPITHELIUM)
Cellular content of the respiratory epithelium
Ciliated columnar cells: Most common, each cell has about 300
cilia
Goblet cells: Secret mucous (Found in frequency)
Brush cells: Have short microvilli, nerve fibers, sensory function
Basal cells: Are rounded STEM CELLS that located near basal
lamina and show mitotic figures
Small granule cells
Nasal Cavity
The Lamina Propria
(Subepithelial CT)
Mucous Glands Serous Glands Venous Sinuses lymphoid elements
CT Lamina Propria Is richly vascularized,
containing large arterial plexuses and venous sinuses, many
Secretions of nasal mucosa - Bactericides - Lysozymes
Olfactory region The olfactory epithelium
Lamina propria (serous secreting BOWMAN’S GLANDS (Boumans GL) a rich vascular plexus and many axons arising from olfactory cells of the olfactory epithelium)
olfactory epithelium comprises three types of cells:
Olfactory cells olfactory cells are bipolar neurons whose apical aspect (dendrite) is modified to form a bulb known as olfactory vesicle
Sustentacular cells (Supporting Cells)
• Cells that has a striated border composed of microvilli, and
secretory granules
• They provide physical support, nourishment
Basal cells
• Are short basophilic cells
• Their apical aspects do not reach the epithelial surface
they proliferate and replace both two other cells
Olfactory
Epithelium
(Sustentacular cells)
(bipolar neurons)
Transition between the Naso and the Oro-
pharynx
The naso-pharynx
The upper part of the pharynx which –
Anteriorly is open into the nasal cavity through posterior
nares,choana!
Posteriorly and laterally is surrounded by the muscular tissue
caudally is continued with the oropharynx and larynx
the epithelium of the pharynx is PSEUDOSTRATIFIED
CILIATED COLUMNAR
goblet cells and small glands (mucous, serous and mixed)
Accumulations of lymphatic tissue
pharyngeal tonsil – posteriorly
Tubal tonsils – laterally both are found in the lamina propria
The middle layer of the pharynx is of muscular character
being formed by bundles of the striated muscles
Pharynx Oro-pharynx
It is lined by a STRATIFIED SQUAMOUS NON-KERATINIZING
TYPE OF EPITHELIUM and lacks both muscularis mucosae and
submucosa.
The epithelium rests on a lamina propria that contains a thick layer of
longitudinally oriented elastic fibers that appear dark, glassy red located
near the underlying muscularis externa.
Lamina propria – loose-dense irregular CT
Vascularized
Seromucous gland: Mucous glands seen in this muscular layer in some
of our glass slides are the extensions of those present in the lamina
propria.
Lymphoid tissue – posterior: pharyngeal tonsil
Skeletal muscle-epimysium
The muscularis externa is composed of somewhat irregularly arranged
skeletal muscle, the longitudinal and constrictor muscles of the pharynx.
Larynx – voice box Additional function:
Phonation
Prevent food/drinks – respiratory system
Tube : cartilage (hyaline, elastic) – ligaments – skeletal muscles
(intrinsic-extrinsic)
Epiglottis – elastic cartilage
Stratified squamous non keratinized epithelium
Pseudostratified (respiratory epithelium)
Vestibular fold – false vocal cord (superior)
Vocal fold - true vocal cord (inferior) - stratified squamous
Vocalis muscle
vocal ligament – regular dense elastic CT
is an elastic cartilage of larynx
It is lined by stratified squamous epithelium on lingual surface
Pseudostratified ciliated columnar epithelium lined the laryngeal side
Serous and mucous glands located in lamina propria
Epiglottis
Trachea–extrapulmonary bronchus
Mucosa
Respiratory epithelium – Pseudostratified ciliated columnar
epithelium: goblet, cilated columnar, basal, brush, serous, DNES
cells
Lamina propria – loose fibroelastic-mucous, seromucous gl-
lymphoid tissue --elastic lamina
Submucosa-dense irreg. fibroelastic CT, mucous-
seromucous gl- lymphoid tissue
Adventitia – fibroelastic CT - C ring hyaline cartilage (p
cartilaginea) – fibrous CT – smooth muscle (p.
membranacea)
Lamina propria
composed of loose fibroelastic CT, contain seromucous glands and lyphoid elements, elastic lamina separate this layer from submucosa
Submucosa
Subnucosa is composed of dense irregular fibroelastic CT that houses mucous and seromucous glands, rich in blood and lymph supply
Adventitia
Adventitia is a fibroelastic CT that houses C-shaped hyaline cartilage, at posterior aspect of cartilage, there is a dense band of smooth muscle cells known as trachealis muscle
Trachea • The Mucosa
• Respiratory epithelium composed of 6 cell types located on a thick basement membrane
• Goblet cells are about 30% of cells, produce mucinogen
• Ciliated columnar cells about 30% of cells, are tall which have cilia and microvilli
• Basal cells are also about 30% of cells, they are undifferentiated stem cells
• Brush cells are just 3% of cells, they are narrow columnar cells that their function is unknown, but nerve ending associated with them
• Serous cells are about 3% of cells, they are columnar and have serous granule
• DNES cells, constitute about 3-4% of cells, have numerous granule in basal cytoplasm which is contain various pharmacological agents
Lung
Intrapulmonary bronchus
(2ndary -3tiary: lobe –
broncho pulmonary segment)
Mucosa –folded app
Respiratory epithelium
L propria – fibroelastic-
seromucous gl-lymphoid
nodules
--Smooth muscles-spiral
Submucosa-seromucous
gl-lymphoid nodules
Adventitia – plates of
cartilage (hyaline)
Bronchioles
Mucosa
Pseudostratified columnar
epithelium- goblet cells
ciliated simple columnar
ciliated cuboidal (with
Clara cells)
Lamina propria
No glands
Elastic fibers
Smooth muscles – helical
loose meshwork –
surrounded by fibroelastic
CT
Bronchial Tree
is composed of:
2 primary bronchus that enter lungs
3 lobar ( secondry) bronchus on right and 2 on the left
Segmental (tertiary) bronchus
bronchioles
Terminal bronchioles
Respiratory bronchioles
Progressively airways decreased in size and cartilage, glands,
goblet cells, and the height of epithelial cells
But increase smooth muscle cells and elastic tissue
Primary Bronchi
(Extrapulmonary)
Primary bronchi is
identical to trachea,
but have smaller
diameter and thinner
wall
Cartilage is in form
of irregular plates
Smooth muscle
located between
lamina propria and
submucosa as 2
distinct layers
PB
Bronchioles have no any cartilage or glands but have few Goblet cells In larger bronchioles epithelium is simple columnar ciliated, with
occasional goblet cells In smaller bronchioles epithelium change to Simple cuboidal,
with no goblet cells Bronchioles have a smooth muscle coats surrounded by
fibroelastic connective tissue
Terminal bronchioles are terminus of conducting portion they are lined by cuboidal cells(some with cilia) and Clara cells which have
domed apical surface Lamina propria is a fibroelastic CT, 1-2 layer of smooth muscle cells separate it from
adventitia
CLARA CELLS ( exocrine bronchiolar cells) • Clara cells are columnar with dome-shaped apex • Secretory granules which secret glycoproteins and surfactant-like materials • degrade toxins(SER) • divide to replace other cells • antimicrobial peptide
Terminal Bronchiole
Respiratory Bronchioles
are a transitional zone
between conducting and
respiratory tissues
Alveoli branching from their
walls
are lined by ciliated cuboidal
epithelium with Clara cells
that change to type I alveolar
cells
Smooth muscle cells and
elastic fibers underlie
epithelium
Respiratory Bronchiole
Alveolus Small air sac - gas exchange
Between alveoli – interalveolar septum – alveolar pores
Connective tissue: elastic, reticular (coll III) – lymphoid tissue
Macrophages, fibroblast, myofibroblast, mast cells
Continuous capillary bed (from pulmonary artery vein)
Both side
Type I Pneumocytes/alveolar cells - squamous alveolar cells) –
tight junction – basal lamina – very thin region permeable to
gasses
Type II Pneumocytes/alveolar cells - great alveolar cell – septal
cells – surfactant – surface tension↓ ≠ collapse
Alveolar walls & Alveolar cells
Cells of the Alveolar Septa
Endothelial cells are nonfenestrated with a thin dark nucleus, and
pinocytotic vesicles
Type I squamous cells that cover most of alveolar surface area, they have
pinocytotic vesicles
Type II (greater alveolar) cells are cuboidal, located on alveolar surface
where septa intersect, they have foamy cytoplasm, surfactant granules
(reduces surface tension to keep alveoli open during expiration)
Alveolar macrophages that are known as dust cells
Interstitial cells consist of fibroblasts and mast cells
Elastic & reticular fibers
•95% of the alveolar surface is composed of the simple squamous cells which are known as type I pneumocytes
•occluding junction attaches to other cells
•have basal lamina,
•alveolar pore formed by fusion of two adjacent type I cells
Type I pneumocytes (Squamus alveolar cells)
Type II pneumocytes (Septal cells)
•They are more numerous than type I
•cover just 5% of the alveolar surface
• located among type I cells, cuboidal with dome-shaped apical
•Located where adjacent alveoli separated by septum
•They have an abundance of RER, developed golgi complex, their lamellar bodies contain pulmonary surfactant
Type I Pneumocytes
Type II Alveolar or Type II pneumocytes
Also known as Septal cells
Rounded or cuboidal
secretory cells with
microvilli
Secretory granules are
made of several layers-
Multilamellar bodies.
These lamillar bodies are
cytoplasmic inclusions
made up of phospholipid
which combines with other
chemicals to form
surfactant & then ooze out
of the cell by exocytosis.
Pulmonary Surfactant – is
the fluid secreted that
spreads over the alveolar
surface
These cells can multiply to
replace damaged cells.
Surfactant also has
bactericidal properties
Type I and II Pneumocytes, capillaries and Dust
cells
Alveolar Macrophages or Dust cells Derived from Monocytes
and are part
mononuclear
phagocytic system.
Either seen in the septa
or alveoli
Cytoplasm contains
phagocytosed inhaled
carbon and dust
particles
Inhaled carbon and dust
particles are passed on
to them from
pneumocyte I through
pinocytic vesicles
Alveolar
Macrophages or
Dust cells
Migrate from septum to
alveolar surface and are
carried to the pharynx
through sputum
Main function is to clean
the alveoli of invading
microorganisms and
inhaled particulate matter
by phagocytosis
Trachea Bronchus Tertiary bronchus Bronchiole Respiratory
bronchiole
Epithelium Pseudostra
tified
Columnar Cuboidal
Goblet cells +++ ++ ++ + Absent
Clara cells Absent Absent Absent + +
Muscularis
mucosae Absent + ++ +++ +++
Mucous glands +++ ++ + Absent Absent
Cartilage +++ ++ + Absent Absent
Alveoli Absent Absent Absent Absent +