L2 Respiratory Histology PDF

Histology - respiratory Respiratory system ( ) LECTURE (2) Respiratory system (2) Dr. M. Shalaby Histology - respiratory Respiratory system ( ) ① MUCOSA: EPITHELIUM: (PSEU...

Histology - respiratory Respiratory system ( ) LECTURE (2) Respiratory system (2) Dr. M. Shalaby Histology - respiratory Respiratory system ( ) ① MUCOSA: EPITHELIUM: (PSEUDO-STR. COLUMNAR CILIATED WITH GOBLET CELLS.)  Most abundant cell CILIATED CELLS  Columnar ciliated, cilia beat towards larynx. GOBLET CELLS  Expanded apical part distended with mucin granules. BASAL CELLS  Stem cells  Columnar with few microvilli. BRUSH CELLS  Associated with nerve endings → may have a sensory role (chemoreceptors)  Small granule cell have neuroendocrine function KULCHITSKY CELLS  Secretes serotonin & calcitonin, acetyl choline. SEROUS CELLS  Apical electron dense granules. Produce serous secretion. CORIUM (LAMINA PROPRIA):  Loose C.T rich in elastic fibers, blood vessels.  Elastic fibers condense to form elastic membrane () corium & submucosa. Dr. M. Shalaby Histology - respiratory Respiratory system ( ) ② SUBMUCOSA:  Loose CT contains tracheal glands which: Mixed (mucus and serous). Open into the surface epithelium. ③ FIBRO-CARTILAGINOUS COAT:  Dense CT contains 16-20 C-shaped rings of hyaline cartilage.  Arranged above each other.  Maintain patency of trachea  Gaps are bridged by smooth muscle. ④ ADVENTITIA:  Dense CT contains blood vessels Dr. M. Shalaby Histology - respiratory Respiratory system ( ) I. Extra-pulmonary bronchi: The same structure as trachea II. Intra-pulmonary bronchi (Lobar Bronchus): formed of: MUCOSA EPITHELIUM Pseudostratified columnar ciliated with few goblet cells. CORIUM Rich in elastic fibers. MUSCLE LAYER  Spirally arranged smooth muscle fibers. ADVENTITIA  Hyaline cartilaginous plates  Mucous & serous glands.  Lymphatic nodules. Dr. M. Shalaby Histology - respiratory Respiratory system ( ) TRACHEA INTRAPULMONARY BRONCHUS LUMEN  Wider  Narrower WALL  Flattened posteriorly  Circular  Highly folded allover the MUCOSAL FOLDS  Present only posteriorly circumference  Pseudostratified columnar EPITHELIUM  Same but fewer goblet cells ciliated with goblet cells  No elastic membrane ELASTIC  Present in mucosa between  But elastic fibers distributed ( ) MEMBRANES corium & submucosa cartilaginous plates in adventitia. SUBMUCOSA  Present  Absent GLANDS  Present in submucosa  Present between the plates  Irregular numerous cartilage CARTILAGE  C-shaped cartilaginous rings plates  Few, bridge the gap of  Complete muscle layer surround MUSCLE FIBERS  C-shaped ring the mucosa LYMPHATIC  Absent  Lymphatic nodules in adventitia NODULE Dr. M. Shalaby Histology - respiratory Respiratory system ( ) DIAMETER Less than 1 mm. STRUCTURE MUCOSA ① Ciliated cells: Simple columnar ciliated. EPITHELIUM Few Goblet in larger bronchioles ② Smaller bronchioles lined by simple cuboidal (many with cilia) and no goblet cells CORIUM C.T rich in elastic fibers. MUSCLE LAYER Well-developed spirally arranged smooth muscle fibers. ADVENTITIA: C.T WHICH HAS  No Cartilage.  No Glands. Dr. M. Shalaby Histology - respiratory Respiratory system ( ) DEF:  The smallest and terminal part of the conducting part. STRUCTURE:  Cubical ciliated cells alternating with Clara cells (50 % of lining cells).  Brush cells (chemoreceptors).  Small granule cells  No goblet cells  Clara cells : Columnar cells Dome-shaped apices with short microvilli and apical secretory granule 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. Dr. M. Shalaby