histology of respiratory system

Histology of Respiratory system

Chantha JayawardenaDBS

10/11/10

Why should I learn..RS

Objectives

• Components• Functions of each component• Structural features (describe and draw) of

components including structure-function relationship

• Identify (LM)• Physiological aspect• Clinical

Functions

Atmospheric airRTDry

Full of dust

Components

Nose

Pharynx

Larynx

Upper respiratory tract

Components

• Divide dichotomously with decreasing diameter

Trachea faculty.ksu.edu.sa

FOD. SL

Components

• Divide dichotomously with decreasing diameter

• Changes takes place gradually

faculty.ksu.edu.sa

FOD. SL

Components

Nasal cavity

Pharynx

Larynx

Trachea

Conducting portion

Respiratory portion

Conditioning air• Adjustment

temperaturehumidity

• Purification /cleaningdust removal

Gas exchange• Between blood and RP

Minimise damage• Against foreign particles

Structure including histology

Variations• Epithelium (thickness, cilia, goblet cells)• Lamina propria (LP)• Submucosa (SM)• Cartilage• Smooth muscles

Nasal cavity

• Cartilages, bones, mucous membrane

• Chonchae (increase surface area and

turbulent airflow – increase contact

between air and MM)

• Hairs (vibrissae) – (trap large particles)

Nasal cavity

Histology of nasal cavity

• Respiratory epithelium (pseudostratified ciliated)

Vein

Vein Vein Vein

Epithelium

Bone

Lamina propria

Veins ; Swell bodies

http://www.lab.anhb.uwa.edu.au

Histology of nasal cavity

• Respiratory epithelium (pseudostratified ciliated)

Mag

Mag

Vein

Vein Vein Vein

Epithelium

Bone

* *

Lamina propria


Pharynx and Larynx

• Cartilages and muscles

• Mucous membrane

– Epithelium • (Pseudostratified -

Respiratory side

• (Stratified squamous

Food/ oral side)

Epiglottis - Histology

• Elastic cartilage and mucous membrane

Mag


Trachea

• Hyaline cartilage & smooth muscle

• 16-20 “C” shaped rings (support)

• Smooth muscle (trachealis) bridge open ends posteriorly (control DM)

• Between rings- fibroelastic tissue (allow expansion)

www.kgu.de

Trachea - histology

Mag

Lamina propria

Epithelium

Submucosa

Cartilage


Trachea

• Draw and label

Principal / primary / main bronchi - histology

• Epithelium similar to trachea (goblet cells )

• Cartilages – interconnected plates

• Smooth muscles beneath the LP

• Submucosa – seromucous glands

Bronchi - histology

• Diameter decreases

• Epithelium similar to trachea

• Shape and arrangement of the cartilage and smooth muscle are different

• With decrease of DM – Cartilage ring become irregular isolated plates

• Smooth muscles in the LP are spirally arranged

• Lymphocytes & lymphoid aggregations in the LP

Segmental / Tertiary bronchi

• Epithelium – less stratified, less goblet cells

• Smooth muscles prominent in the LP

• Less submucosa and seromucous glands

• Few isolated cartilage plates



Bronchus


• Draw and label

Bronchioles

Bronchioles

• Draw and label

Respiratory bronchiloes

• Sac like alveoli along the wall

• Epithelium – ciliated cuboidal

• No goblet cells, Clara cells present

• No cartilage

• Little smooth muscle in the LP

• No submucosa

Alveolar duct and alveoli

• Exchange of gas

• Epithelium simple squamous

• Elastic and reticulin fibers – elastic recoil & prevent over expansion

• Smooth muscles only at the openings of alveloar ducts

• Cigarette smoking – break down alveolar tissue and impair repair of tissue - emphysema


• Cells become very thin for gas exchange

• Several cell types

• Squamous alveolar cells (Type I) – 97 %– Desmosomes & tight junctions present -

prevent leakage of tissue fluid


• Surfactant secreting cells (Type II)– 3 % -

reduce surface tension– Round cells

– Can proliferate & produce new type I & II cells

– Respiratory distress syndrome – Immature baby


• Alveolar macrophages – interalveolar septum, surface of alveoli


Alveoli and blood-gas barrier

• Epithelium of alveoli & capillaries become very thin

• Basement membrane of two epithelia fused each other – thin barrier

Blood-gas barrier

• Draw and label

Trachea Bronchus Bronchiole Alveoli

Epithelium

Lamina propria

Submucosa

cartilage

Thickness of epitheliumCiliaGoblet cellsSmooth muscle

Cartilage

Sero-mucous glandsFunction

Trachea Bronchus Bronchiole Alveoli

References

http://www.lab.anhb.uwa.edu.au//

histology of respiratory system

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