RESPIRATORYRESPIRATORYRESPIRATORYRESPIRATORYRESPIRATORYRESPIRATORYRESPIRATORYRESPIRATORY

SYSTEMSYSTEMSYSTEMSYSTEMSYSTEMSYSTEMSYSTEMSYSTEM

RESPIRATORY SYSTEM

nnnn CONDUCTINGPORTION

nnnn RESPIRATORYPORTION

SKELETAL MUSCLES AND BONES ARE REQUIRED

FOR RESPIRATORY SYSTEM FUNCTION

STERNUM

INTERCOSTAL MUSCLES

DIAPHRAGM

RIBS

GENERAL ORGANIZATIONAL PATTERN OF CONDUCTING PORTION OF RESPIRATORY SYSTEM

���� MUCOSALuminal sheet epithelium(typically “respiratory epithelium”)Lamina propria (loose FECT)

���� SUBMUCOSA (mod. dense FECT)(not always present or merged

with lamina propria, serous or mixed glands maybe present in the lamina propria or submucosa)

���� “MUSCULARIS” EXTERNA (may be smoothmuscle, cartilage, or bone)

���� ADVENTITIA or SEROSA (absent in nasal cavity)

CELL TYPES FOUND IN

“RESPIRATORY EPITHELIUM”

PREDOMINANT CELL TYPES

���� Ciliated columnar cells – move

mucus

���� Goblet cells – secrete mucus

���� Basal cells – replace damaged cells

LESS COMMON CELL TYPES

���� Brush cells – sensory receptor cells

���� Dense core granule cells (Small granulecells) – enteroendocrine cells

���� Clara cells (trachea and bronchi) – protein

secreting cells, secrete surfactant

PREDOMINANT CELL TYPES

FOUND IN “RESPIRATORY EPITHELIUM”

Source: Lentz. 1971. Cell Fine Structure.

Ciliated columnar cell Goblet cell (Mucous cell)

Basal cell

“RESPIRATORY EPITHELIUM”

Source: Weiss. 1983. Histology. Cell and Tissue Biology. 5th Edition.

Ciliated cells

Goblet cell/

Mucous cell

Basal cell

Brush

cells

Small granule cell

(surfactant)

“RESPIRATORY” EPITHELIUM

Cilia

Basement membrane

Goblet cells

Ciliated cells

Small

granule

cellBasal cell

EPITHELIA OF REGIONS WITHIN

NASAL CAVITIES

���� VESTIBULE orNOSTRIL Stratified squamous

sheet epithelium

���� RESPIRATORY SEGMENT

”Respiratory

epithelium”

���� OLFACTORY SEGMENT Olfactory

epithelium

RESPIRATORY SEGMENT

OLFACTORY SEGMENT

NOSTRIL

NASAL CAVITIES/ NASAL PASSAGEWAYS

Source: Plate 88, Figure 1 in Ross et al. 1995. Histology. A Text and Atlas. 3rd Edition.

OEp = olfactory

epithelium

OM = olfactory

mucosa

Rep = “respiratory

epithelium”

EB = bone

CELL TYPES FOUND IN

OLFACTORY EPITHELIUM

nnnn Sustentacular orsupporting cells

nnnn Olfactory cells

nnnn Basal cells

nnnn Brush cells

Mucosa of the Olfactory Segment

of the Nasal Cavity

Mucosa of the Olfactory Segment

of the Nasal Cavity

Source: Plate 88, Figure 2 in Ross et al. 1995. Histology. A Text and Atlas. 3rd Edition.

SC = supportive

cells

OC = olfactory

neuron cell bodies

BC = basal cells

BG = olfactory

glands (serous)

N = peripheral

nerves

V = blood vessels

C = capillaries

NASAL CAVITIES/NASAL PASSAGEWAYS

are separated from oral cavity by PALATE

RESPIRATORY SEGMENT

OLFACTORY SEGMENT

NOSTRIL

Modified from: Figure 18.1 in Ross et al. 1995. Histology. A Text and Atlas. 3rd Edition.

HARD PALATE SOFT PALATE

SOFT PALATE

Source: Hammersen. 1980. Histology.

“Respiratory epithelium”

of Nasal Mucosa

ORAL CAVITY

side

NASAL CAVITY

side

PHARYNX

”Respiratoryepithelium”

Stratified squamoussheet epithelium

Modified from: Figure 18.1 in Ross et al. 2003. Histology. A Text and Atlas. 4th Edition.

RESPIRATORY SYSTEM

nnnn NASAL CAVITIES/ NASAL PASSAGEWAYS

n PHARYNX -nasopharynx, oropharynx

n LARYNX

n TRACHEA

n EXTRAPULMONARYBRONCHI

n LUNGS

LARYNX and TRACHEA

Source: Leeson & Leeson. 1981. Histology. 4th Edition.

Food

cartilage

cartilage

cartilage

bone

Surface View Mid-longitudinal Section

EPIGLOTTIS of LARYNX

Source: Hammersen. 1980. Histology. A Color Atlas of Cytology, Histology and Microscopic Anatomy. 2nd Edition.

Stratified squamous

epithelium

Elastic Cartilage

Stratified squamousor pseudostratified

columnar epithelium

LARYNX

Source: Hammersen. 1980. Histology. A Color Atlas of Cytology, Histology and Microscopic Anatomy. 2nd Edition.

Ventricular fold/

false vocal cord

Vocal fold/

true vocal cord

Epiglottis

Stratified squamous

sheet epithelium

Pseudostratified ciliated

columnar sheet epithelium

LARYNX

Source: Hammersen. 1980. Histology. A Color Atlas of Cytology, Histology and Microscopic Anatomy. 2nd Edition.

Intrinsic glands in

Lamina propria of

Mucosa

Vocalis muscle

Epiglottis

Vocal ligament

Cartilaginous plate in

“Muscularis” Externa

Striated skeletal

muscle tissue in

“Muscularis” Externa

Cartilaginous plate in

“Muscularis” Externa

RESPIRATORY SYSTEM

nnnn NASAL CAVITIES/ NASAL PASSAGEWAYS

n PHARYNX -nasopharynx, oropharynx

n LARYNX

n TRACHEA

n EXTRAPULMONARYBRONCHI

n LUNGS

Trachea

���� Mucosa“Respiratory” epithelium (+/- Clara cells)Lamina propria of loose FECT

���� SubmucosaLoose to moderately denseFECT,

denser than lamina propria, may contain compound tubuloacinar glands

���� “Muscularis”externaHyaline cartilages (horseshoe-shaped “rings”)Smooth muscle across open ends of cartilagesModerately dense FECT connects adjacent rings

���� AdventitiaLoose FECT

TRACHEA

Source: Leeson & Leeson. 1981. Histology. 4th Edition.

Adventitia “Muscularis”

Externa

(trachealis muscle)

Mucosa

luminal

epithelium

in submucosa

TRACHEA

TRACHEA

Cilia

Basement membrane

Goblet cells

Ciliated cells

Small

granule

cellBasal cell

LUMINAL EPITHELIUM OF TRACHEA

(“Respiratory” Epithelium)

RESPIRATORY SYSTEM

nnnn NASAL CAVITIES/ NASAL PASSAGEWAYS

n PHARYNX -nasopharynx, oropharynx

n LARYNX

n TRACHEA

n EXTRAPULMONARYBRONCHI

n LUNGS

Bronchus (very similar to Trachea)

���� Mucosa“Respiratory” epithelium (+/- Clara cells)Lamina propria of loose FECT

���� SubmucosaLoose to moderately denseFECT,

denser than lamina propria, may contain compound tubuloacinar glands

���� “Muscularis”externaHyaline cartilages (horseshoe-shaped “rings”)Smooth muscle across open ends of cartilagesModerately dense FECT connects adjacent rings

���� AdventitiaLoose FECT

RESPIRATORY SYSTEM

Source: Leeson & Leeson. 1981. Histology. 4th Edition.

PULMONARY LOBULE

ORGANIZATION OF LUNG

Source: Leeson & Leeson. 1981. Histology. 4th Edition.

3-9 = intrapulmonary bronchi

10 = large bronchiole

tb = terminal bronchiole

rb = respiratory bronchiole

ad = alveolar duct

as = alveolar sac

a = alveolus

l = lobule

PULMONARY LOBULE

HISTOLOGICAL FEATURES OF PULMONARY COMPONENTS

ORGANIZATION OF LUNG

Source: Gartner & Hiatt. 1994. Color Atlas of Histology. 2nd Edition.

ORGANIZATION OF LUNG

Source: Freeman & Bracegirdle. 1976. An Advanced Atlas of Histology.

alveoli

ORGANIZATION OF LUNG

Source: Leeson & Leeson. 1981. Histology. 4th Edition.

3-9 = intrapulmonary bronchi

PULMONARY LOBULE

Intrapulmonary Bronchi���� Mucosa

“Respiratory” epithelium (+/- Clara cells)Lamina propria of loose FECT

���� “Muscularis”Spiral bundles of smooth muscle

���� SubmucosaLoose to occasionally moderately dense FECT,may contain compound tubuloacinar glands

���� “Muscularis”externaHyaline cartilages (horseshoe-shaped “rings”)Smooth muscle across open ends of cartilagesModerately dense FECT connects adjacent rings

���� AdventitiaLoose FECT

INTRAPULMONARY BRONCHUS

Source: Jungueira et al. 1975. Basic Histology. 4th Edition.

Mucosa

Intrinsic glands in

Lamina Propria

FECT

Cartilaginous plate in

“Muscularis” Externa

Bronchiole

branching off

of bronchus

Hyaline Cartilage

Smooth Muscle

Loose FECT

Pseudostratified Columnar Epithelium

An Intrapulmonary Bronchus

BRONCHIOLES

Source: Leeson & Leeson. 1981. Histology. 4th Edition.

PULMONARY LOBULE

���� MUCOSALuminal sheet epithelium (ranges from pseudostratifiedciliated columnar in largebronchioles to simplecuboidal with mixed ciliatedand Clara cells in terminalbronchioles)Lamina propria = loose FECT

����“MUSCULARIS” = bundles of smooth muscle

<1 mm in diameter

No cartilage in wall

TYPES OF BRONCHIOLES

Source: Leeson & Leeson. 1981. Histology. 4th Edition.

10 = large bronchiole

tb = terminal bronchiole

rb = respiratory bronchiole

nnnn LARGE BRONCHIOLESPseudostratified ciliated columnar

sheet epithelium to simple columnarsheet epithelium

nnnn TERMINAL BRONCHIOLESMainly simple cuboidal sheetepithelium

nnnn RESPIRATORY BRONCHIOLESSimple cuboidal sheet epithelium

(mainly Clara cells)

CELL TYPES FOUND IN

LUMINAL EPITHELIUM OF BRONCHIOLES

nnnn Ciliated cells

nnnn Basal cells

nnnn Goblet cells

nnnn Brush cells

nnnn Small granule cells

nnnn Clara cells

Source: Ross et al. 1995. Histology. A Text and Atlas. 3rd Edition.

Clara cell Ciliated cellCiliated cell

BRONCHIOLE

Source: Burkitt et al. 1993. Wheater’s Functional Histology. A Text and Colour Atlas.

Alveoli are where

the action is (at

least in terms of

gas exchange)

ORGANIZATION OF LUNG

Source: Freeman & Bracegirdle. 1976. An Advanced Atlas of Histology.

alveoli

ALVEOLI or AIR SPACES

AS = alveolar sacA = alveolus

ALVEOLI (AIR SPACES)

Source: Leeson & Leeson. 1981. Histology. 4th Edition.

ad = alveolar duct

as = alveolar sac

a = alveolus

Occur in the walls of

���� Respiratory bronchioles

���� Alveolar ducts

���� Alveolar sacs

CONSIST OF:

���� Alveolar Epithelium

���� Thin region of highly vascularized FECT

CELL TYPES FOUND IN

ALVEOLAR EPITHELIUM

nType I Pneumocytes [gas exchange]

nType II Pneumocytes [secrete

surfactant (mix of proteins and lipids)]

nBrush Cells [sensory receptors]

nPulmonary Macrophages

[phagocytosis]

CELL TYPES FOUND IN

ALVEOLAR EPITHELIUM(as observed at TEM level)

Source: Lentz. 1971. Cell Fine Structure.

Type I Pneumocyte(and adjacent capillary)

Type II Pneumocyte

Alveolar Wall Structure – Type I Cells

Alveoli

Lung Injected to Show CapillariesCapillaries (red structures)

ALVEOLI ARE SITES

OF GAS EXCHANGE

AIR

RBC

BLOODBLOOD

Alveolar Wall Structure –Type II or

Great Alveolar Cells

CELL TYPES

FOUND IN

ALVEOLI(as observed at the LM level)

In addition to Type I and Type II alveolar cells

(pneumocytes), macrophages

are frequently observed migrating along the alveolar

surface. Macrophages are frequently detached from the

surface during processing.

Criteria for Classifying Intrapulmonary Structures

Structure Lining Epithelium Other Features

Bronchi pseudostratified hyaline cartilage in wallcolumnar usually + smooth muscle

Bronchioles pseudostratified no hyaline cartilage in wallcolumnar to smooth muscle presentsimple cuboidal,no squamous

Respiratory >50% cuboidal or little or no smooth muscle,Bronchioles columnar, <50% usually some loose FECT

squamous (butsquamous present)

Alveolar Ducts <50% cuboidal, no smooth muscle, looseAlveolar Sacs >50% squamous FECT sparse or absent

ALVEOLI & BRONCHIOLES

TB = terminal bronchioleRB = respiratory bronchioleAD = alveolar ductAS = alveolar sac