Respiratory System - Mansoura University PDF

The Respiratory System By Dr. Shereen Hamed Lecturer of Histology & Cell Biology Faculty of Medicine, Mansoura University  RESPIRATORY SYSTEM Respir...

The Respiratory System By Dr. Shereen Hamed Lecturer of Histology & Cell Biology Faculty of Medicine, Mansoura University  RESPIRATORY SYSTEM Respiratory Conducting part part 1 - Respiratory 1Nasal cavities bronchioles. and nasal sinuses. 2 Alveolar 2 Nasopharynx. ducts. 3 Larynx. 3 Alveolar 4 Trachea. sacs. 5 Bronchi. 4 Alveoli 6 Bronchioles. 7Termin al bronchioles Conducting Portion  Nasal Cavity The vestibule 2 Nasal fossae Respiratory Olfactory external dilated part. region region Lined by: - Thin skin v - Thick hairs ( ibrissae) for filtration of air.  Respiratory region Olfactory region Site Inferior 2/3 of the nasal fossae. Upper 1/3 of the nasal fossae (roof). Mucosa: Respiratory mucosa Olfactory mucosa Epith. Pseudostatified Columnar Neuroepithelium Ciliated with goblet cells. Corium  Dense fibroelastic CT  Dense fibroelastic CT Respiratory region  Nasopharynx Epithelium Corium pseudo-st. Pharyngeal col. ciliated tonsils with goblet (adenoids). cells  Larynx a rigid short tube between the pharynx and trachea. Epithelium Corium pseudo-st. col. laryngeal ciliated with cartilages goblet cells (reinforces its wall). Except …..  Epiglottis  It acts as a valve to prevent swallowed food or fluid from entering the trachea. Epithelium Corium Laryngeal contains glands surface: pseudo-st. col. ciliated with goblet cells  Vocal cords 2 pairs of mucosal folds that extend into the lumen False vocal cords True vocal cords -upper pair -lower pair. - Protect from -phonation F.B. -St. sq. non -Pseudost. Col. keratinized ciliated  Trachea Mucosa Submucosa Fibro-Cartilaginous coat Adventitia. Epith. corium Tracheal glands  Trachea Mucosa Submucosa Fibrocartilagenous coat Adventitia  Mucosa Epithelium Corium 7 cells -rich in elastic fibers, Pseudo-str. Col. blood vessels ciliated with - Elastic fibers goblet cells. condense >>>elastic membrane ( ) corium & submucosa  Epithelium Ciliated cells goblet cells Basal cells Brush cells Serous cells Migratory cells Kulchitsky cells Neuro-endocrine  Trachea Mucosa Submucosa Fibro-Cartilaginous coat Adventitia. Tracheal glands Mixed (mucus & serous) Open into the surface epithelium  Trachea Mucosa Submucosa Fibro-Cartilaginous coat 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  Bronchi Extra- Intra- pulmonary pulmonary bronchi bronchi -Mucosa - Submucosa -Mucosa -Fibrocartilagenous - Muscle layer -adventitia -adventitia  Intrapulmonary Bronchi 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 & Ciliated with +++ elastic fibers fibers. serous goblet G. Lymphatic Bronchi  Trachea Intrapulmonary bronchus Lumen Wider Narrower Wall Flattened posteriorly Circular Mucosal Folds Present only posteriorly Highly folded allover the circumference Epithelium Pseudostratified columnar Same but fewer goblet cells ciliated with goblet cells Elastic membranes Present No elastic membrane  Trachea Intrapulmonary bronchus Submucosa Present Absent Glands Present in submucosa Present between the plates Cartilage C-shaped cartilaginous rings Irregular numerous 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.  Bronchiole Less than 1 mm in diameter Mucosa Muscle layer Adventitia. Well No Cartilagenous Plates Epith. Corium: developed No Glands. Simple Spirally No Lymphatic N. columnar +++ elastic arranged ciliated fibers smooth -Clara muscle fibers. cells Clara cells: Columnar cells with rounded apex. oRepresent 50% of cells. oSecretes agent rich in lipoprotein which prevents luminal adhesion.  Terminal bronchioles The smallest and terminal part of the conducting part. Structure: Cubical ciliated cells alternating with Clara cells (50 % of lining cells) Respiratory Part  Respiratory bronchioles Arise from the terminal bronchioles. 0.2-0.5 mm. Lined by cubical cells which are surrounded by CT contains elastic fibers & smooth muscle fibers. The wall is interrupted by alveoli which opens directly into the lumen.  Alveolar duct They are narrow tubes where the alveoli opens in their wall.  Pulmonary Alveoli - Minute air spaces. - Functional and structural unit of the lung Alveolar Interalveolar Alveolar pores epithelium septum Type 1 Type 2 pneumocytes pneumocytes Alveolar sac: group of alveoli open into a common central space  Pneumocyte type 1 Pneumocyte type 2 Function through which Gas exchange occurs. - progenitor cells for type 1 and type 2 pneumocytes. - Secrete pulmonary surfactant. Number 95% 5% LM Flat squamous cells less than 0.2 um Cuboidal cells with rounded central thickness slightly thickened area nuclei. containing nucleus. Found at angles of interalveolar septa. EM - Occluding(tight) junctions - Occluding (tight) junctions - Thin basal lamina. - Many mitochondria, many rER -Perinuclear cytoplasm: small golgi, few mitochondria and rER prominent golgi complex -Cytoplasm of thin portion is -electron dense devoid of organelles. lamellar bodies rich in phospholipids.  Pulmonary Surfactant It is a mixture of phospholipids which lines the inner aspect of alveoli. It decreases surface tension so alveolar collapse. prevent  Interalveolar septum Alveolar Capillary C.T. fibers & epithelium network Basement cells membranes pulmonary Septal capillary Of - Reticular f cells, bed alveolar - Elastic f. mast cells, epith. & lymphocytes capillary WBC bed In certain sites, the 2 membranes fuse → alveolar capillary membrane.  Blood air barrier It is the wall separating air in alveoli from blood in llaries capi The fused basal The endothelial Type I alveolar laminae of alveolar cells of capillaries. cells & endothelial cells of capillaries  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