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Home , Respiratory epithelium

PRACTICAL ROADMAP

RESPIRATORY SYSTEM Mrs. A. Jovanović DIVISION OF THE CONDUCTING PORTION RESPIRATORY PORTION

 Nasal cavities  Respiratory bronchioles • Oral cavity  Alveolar ducts • Nasopharynx  Alveolar sacs • Oropharynx  Alveoli •  Trachea  Paired bronchi  Bronchioles  Terminal bronchioles CONDUCTING PORTION OF THE RESPIRATORY SYSTEM

• Slide 67 The nasal cavities and air sinuses

Olfactory mucosa Respiratory mucosa THE AND AIR SINUSES

Olfactory mucosa Air sinus

Nasal cavity Respiratory mucosa OLFACTORY and RESPIRATORY MUCOSA

Bone spicule

Respiratory mucosa

Nasal cavity mucosa Olfactory OLFACTORY MUCOSA

Olfactory “piercing” trough the and olfactory Olfactory nerve

Lamina propria Smooth muscle

mucosa Muscularis Olfactory Bone Blood Indistinct basement (encircled in black) spicule vessels membrane OLFACTORY EPITHELIUM Pseudostratified ciliated epithelium with four cell types and indistinct basement membrane

Olfactory cells (bipolar neuron) with vesicular nuclei Sustentacular‐supporting cells nuclei

Cilia epithelium

Olfactory

Indistinct basement membrane

Basal cells nuclei RESPIRATORY MUCOSA Mucous‐serous glands in the lamina propria epithelium Respiratory Lamina propria mucosa Muscularis

Distinct basement Blood Bone membrane vessels spicule RESPIRATORY EPITHELIUM Pseudostratified ciliated columnar epithelium with five cell types and distinct basement membrane

Columnar cell with apical cilia Note: Small granule cells and brush cells can not be distinguished in the routine H&E Goblet cells preparation and require a special staining. Only their basophilic nuclei can be seen at the different levels of this epithelium epithelium

Respiratory

Distinct basement membrane Basal cells nuclei Trachea

Conducting portion Bronchiole

Terminal Respiratory bronchiole system Respiratory bronchiole Alveolar Respiratory ducts portion Alveolar sack

Alveoli CONDUCTING PORTION TRACHEA

• Slide 32 Trachea and Oesophagus Respiratory mucosa: Respiratory epithelium ‐ pseudostratified ciliated columnar with goblet cells Lamina propria – cellular, loose connective tissue Muscularis mucosa (absent) Submucosa: Dense irregular connective tissue ‐ C shaped hyaline cartilage ring and mucous ‐ serous glands Muscularis Externa Adventitia Submucosa

Tracheal lumen

Respiratory epithelium

Lamina propria

Hyaline cartilage

Trachealis muscle Adventitia TRACHEAL MUCOSA AND SUBMUCOSA

Respiratory epithelium Lamina propria Perichondrium

Hyaline cartilage

Mucous serous glands

Mucosa Submucosa TRACHEAL MUCOSA AND SUBMUCOSA The region where two ends of the hyaline cartilage ring meet

Perichondrium Respiratory epithelium Lamina propria

Hyaline cartilage

Trachealis muscle

Mucous serous glands TRACHEALIS MUSCLE AND ELASTIC SHEETS The region where two ends of the hyaline cartilage ring meet

Hyaline Trachealis muscle cartilage

Elastic sheets

Perichondrium

Note: Wavy elastic fibers are staining very darkly between eosinophilic collagen fibers Lymphatic tissue associated with respiratory system

Nodular lymphatic tissue

Lymphatic vessels

Note: Nodular and diffuse lymphatic tissue and associated lymphatic vessels are constantly present in both lamina propria and submucosa INTRAPULMONARY BRONCHUS

• Slide 97 Hilus of  Intrapulmonary bronchus  Bronchiole  Transitional bronchiole  Respiratory bronchiole INTRAPULMONARY BRONCHUS

Respiratory mucosa: Respiratory epithelium Same as in trachea Lamina propria Muscularis mucosa ‐ present Submucosa Muscularis Externa Adventitia INTRAPULMONARY BRONCHUS Hyaline cartilage plates in the submucosa Mucosa

Submucosa BRONCHIAL MUCOSA AND SUBMUCOSA Respiratory epithelium Lamina propria

Mucosa

Perichondrium

Muscularis mucosa

Submucosa Hyaline cartilage

Glands BRONCHIOLE

• Slide 97 Hilus of lung Bronchiole Respiratory mucosa: Respiratory epithelium – Epithelium varies from pseudostratified ciliated columnar in the proximal part of the bronchiole to ciliated columnar more distally Lamina propria ‐ Loose connective tissue Muscularis mucosa – Circular band of smooth muscle surrounding the circumference of the bronchiole Respiratory epithelium Lamina propria BRONCHIOLE

Mucosa Muscularis mucosa BRONCHIOLAR MUCOSA Respiratory epithelium

Lamina propria

Muscularis mucosa

Cilia

Goblet cell TERMINAL BRONCHIOLE

• Slide 97 Hilus of lung Terminal bronchiole Respiratory mucosa: Respiratory epithelium – simple cuboidal ciliated epithelium with Clara cells Lamina propria – loose connective tissue Muscularis mucosa ‐ smooth muscle band TRANSITION BETWEEN STRUCTURES IN RESPIRATORY TREE

AS

RB AD B TB RB

A

http://medcell.med.yale.edu/histology/respiratory_system_lab.php

B ‐ Bronchiole; TB ‐Terminal Bronchiole; RB ‐ Respiratory bronchiole; AD – ; AS ‐ Alveolar sac; A ‐ Alveolus Blood vessel

TB

Sometimes the transition is not seen but only a cross sections of the individual structures which are the part of the respiratory tree. TB – Transitional bronchiole RESPIRATORY PORTION RESPIRATORY BRONCHIOLE

• Slide 98 Lung Respiratory mucosa: Respiratory epithelium – simple cuboidal ciliated epithelium with dominant Clara cells Lamina propria – loose connective tissue Muscularis mucosa –thin smooth muscle band RESPIRATORY BRONCHIOLE

Clara cells

http://www.studyblue.com/ ALVEOLAR DUCTS and ALVEOLAR SACKS

• Slide 98 Lung Respiratory mucosa: Respiratory epithelium ‐ simple squamous epithelium Lamina propria –scarce loose connective tissue Muscularis mucosa – individual smooth muscle cells ALVEOLAR DUCTS and ALVEOLAR SACKS

Alveolar duct

Alveolar sac Interalveolar septum

Alveolar duct

Smooth muscle Alveolus “knob”

Note: Alveolus – singular, Alveoli ‐ plural ALVEOLI

• Slide 98 Lung Respiratory mucosa: Respiratory epithelium ‐ simple squamous epithelium Lamina propria ‐ scarce loose connective tissue Muscularis mucosa ‐ few smooth muscle cells Alveolus Connective tissue Blood vessel

Endothelium

Pneumocyte type I

Pneumocyte type II

Interalveolar septum INTERALVEOLAR SEPTUM –SEPTAL WALL Site of a blood air barrier • Slide 98 Lung Constituents of the interalveolar septum:

Pneumocyte type I (squamous cell) Pneumocyte type II (cuboidal cell) Connective tissue (cells and fibres) Occasional smooth muscle fibre Blood vessels (lined by ) Dust cells (macrophages) INTERALVEOLAR SEPTUM

Type I Pneumocytes squamous epithelial Endothelial cell cells lining the alveolus

Alveolar Macrophages Dust cells

Capillaries with red blood cells in a single file.

Type II Pneumocytes cuboidal cells in the angles between adjacent alveoli Lamellarlb body A Blood Pneumocyte type II vessel Blood airbab barrier Basal BLlamina

En Blood Endothelium BLBasal vessel lamina

Nucleus

Multinucleated macrophage –Dust cell Endothelium A Lamellar bodylb En Alveolar lumen Lamellar body

Pneumocyte type II BLOOD AIR BARRIER (EMG)

Constituents of the blood air barrier:

Thin layer of surfactant Pneumocyte type I Fused basal laminae Endothelial cell Blood air barrierbab Alveolar lumen

ps Dust cell

dv

Alveolar ps ly lumen Pneumocyte type I

Blood air barrier Capillary lumen Erythrocyte E Pneumocyte type I Bloodbab air barrier ps – pseudopodia; ly – lysosomes; dv – digestion vacuole