L2 respiratory system.pdf

Module 3B  respiratory system histology (Conducting portion 2) Dr. Shereen Hamed Lecturer of Medical Histology [email protected] Learning Outcomes text text Identify the histologi...

Module 3B  respiratory system histology (Conducting portion 2) Dr. Shereen Hamed Lecturer of Medical Histology [email protected] Learning Outcomes text text Identify the histological structure of trachea, respiratory epithelium. Identify histology of lobar bronchus. Identify histology of bronchioles and terminal bronchioles  Learning Outcome 1 Identifiy the histological structure of trachea, respiratory epithelium.  RESPIRATORY SYSTEM Conducting part Respiratory part part responsible for: -conduction of air to and from the lung -conditioning of air  RESPIRATORY SYSTEM Respiratory Conducting part part 1- Nasal cavities and nasal sinuses. 2- Nasopharynx. 3- Larynx. 4- Trachea. 5- Bronchi. 6- Bronchioles. 7- Terminal bronchioles  Trachea Mucosa Submucosa Cartilaginous rings Adventitia. Tracheal Epith. corium glands  Trachea Mucosa Submucosa cartilagenous ring Adventitia  Mucosa Epithelium Corium -rich in elastic fibers, Pseudo-str. Col. blood vessels ciliated with goblet cells. - Elastic fibers condense >>>elastic membrane ( ) corium & submucosa  Epithelium Ciliated cells goblet cells Basal cells Brush cells Serous cells Migratory cells Kulchitsky cells Neuro-endocrine cells  Columnar ciliated, cilia beat towards larynx. Ciliated cells Columnar with few microvilli. Associated with nerve endings>>may have a sensory role Brush cells: goblet cells that have released their mucinogen Have expanded apical part Goblet cells distended with mucinogen granules. Apical electron dense granules. Serous cells Produce serous secretion.  stem cells Basal cells Have neuroendocrine function. Secretes serotonin & Kulchitsky cells calcitonin, acetyl choline.  Trachea Mucosa Submucosa Cartilaginous rings Adventitia. Tracheal glands Mixed (mucus & serous) Open into the surface epithelium  Trachea Mucosa Submucosa Cartilaginous rings Adventitia. Dense CT -Dense C.T. contain contains bl.V. 16-20 c-shaped rings (hyaline cartilage) -above each other - Maintain patency of trachea - Gaps are bridged by smooth muscle  Learning Outcome 2 Identifiy the histological structure of lobar bronchus.  Bronchi Intra-pulmonary Extra-pulmonary bronchi Bronchi (secondary bronchus) (primary bronchus) -Mucosa - Submucosa -Mucosa -Cartilaginous rings - Muscle -adventitia layer -adventitia  Intrapulmonary Bronchus (lobar bronchus) Goblet cells & mucous glands decrease in number as bronchi become smaller and end in bronchioles. Mucosa Muscle layer Adventitia. +++ elastic fibers Hyaline cart. Epith. Spirally arranged Plates Pseudost. Col. Corium: smooth muscle Mucous & serous Ciliated with +++ elastic fibers fibers. G. goblet Lymphatic nodules Bronchi  Trachea Intrapulmonary bronchus Lumen Wider Narrower Wall Flattened posteriorly Circular Mucosal Folds Present only Highly folded allover posteriorly the circumference Epithelium Pseudostratified Same but fewer goblet columnar ciliated cells with goblet cells Elastic Present in mucosa No elastic membrane membranes between the corium but elastic fibers are and the submucosa distributed between the cartilaginous plates in adventitia.  Trachea Intrapulmonary bronchus Submucosa Present Absent Glands Present in submucosa Present between the plates Cartilage C-shaped Irregular numerous cartilaginous rings cartilage plates Muscle fibers Few, bridge the gap of Complete muscle layer C-shaped ring surround the mucosa Lymphatic nodules Absent Lymphatic nodules in the adventitia.  Learning Outcome 3 Identify histology of bronchioles and terminal bronchioles.  Bronchiole Less than 1 mm in diameter Mucosa Muscle Adventitia layer. Epith. No Cartilagenous Plates Simple columnar No Glands. ciliated Well developed Corium: Spirally arranged Few Goblet in smooth muscle +++ elastic fibers larger fibers. bronchioles smaller bronchioles lined by simple cuboidal (many with cilia) with occasional Clara cells and no goblet cells Clara cells: Clara cells are columnar cells with dome-shaped apices with short microvilli and apical secretory granules Functions: 1) protect the bronchiolar epithelium by their secretory product. 2) Detoxifications. 3) produce a surfactant-like material that reduces the surface tension of bronchioles 4) Stem cell.  Terminal bronchioles The smallest and terminal part of the conducting part. Structure: Cubical ciliated cells with many Clara cells  References Principles of histology, (student book of Histology & Cell Biology Department, faculty of medicine, Mansoura university) Basic Histology, text book of histology & cell biology Internet sources Discussion