Respiratory System Histology PDF

Respiratory system Lecture1 Respiratory system Respiratory system Respiratory system Respiratory system The respiratory system provides gaseous exchange between the environment and the blood The human respiratory system maybe subdivided into 2 parts : The conducting portion: which conduct air from e...

Respiratory system Lecture1 Respiratory system Respiratory system Respiratory system Respiratory system The respiratory system provides gaseous exchange between the environment and the blood The human respiratory system maybe subdivided into 2 parts : The conducting portion: which conduct air from environment into respiratory spaces and break out. The respiratory portion: (gaseous exchange)which consist of many interconnected air filled spaces with very thin lining allow rapped gaseous exchange Respiratory system The human respiratory system include : Nose/nasal cavity Pharynx(nasopharynx, oropharynx) Larynx Trachea Bronchi Lungs(bronchial tree and alveoli ) Skeletal muscles(diaphragm , Intercostal muscle) Respiratory system The conduction portions function is to provide a passage way for air , warming , moistening and cleaning it. They consist of : nasopharynx ,larynx , trachea ,bronchi ,bronchioles and terminal bronchiole Conducting portion cleans ,moistens and warms the incoming air by : hair and secretion of sebaceous glands in nasal cavity trap particulate matter. In trachea and lower portion secretions of mucous and serous glands moisten the air, and trapping extraneous matte Respiratory system Nasal cavity : Respiratory system Nasal cavity : Mucosa : Epithelium : anterior portion lined by stratified squamous epithelia , posterior lined by olfactory which is pseudostratified columnar epithelia.and pseudostratified columnar ciliated + goblet cells which called respiratory epithelium , this epithelia. Contain many cell types : ciliated columnar cells goblet cells (mucus secreting) basal cells brush cells dense core granule cell Respiratory system Nasal cavity : The lamina propria of nasal cavity is primarily loose with numerous blood vessels and compound serous tubule-acinar Respiratory system Trachea & extra pulmonary ( primary bronchi ) : Extrapulmonary Intrapulmonary Nasal cavity Secondary bronchi Pharynx Bronchioles Larynx Terminal bronchioles Trachea Respiratory bronchioles Primary bronchi Alveolar ducts & Alveoli Respiratory system Trachea & extra pulmonary ( primary bronchi ) : Mucosa: The epithelia , lining is very similar to pseudostratified ciliated columnar (respiratory) epithelia of nasal cavity. The lamina propria consist of thin layer of loose connective tissue which is rich in elastic tissue and contain diffuse or nodular lymphoid tissue Submucosa : dense connective tissue contain tubule acinar glands Respiratory system Trachea & extra pulmonary ( primary bronchi ) : The muscularis externa : contain 3 types of tissues Tracheal rings(C-shaped), open dorsally) of hyaline cartilage enclosed by a perichondrium of dense regular collagenous C.T. In intrapulmonary bronchi hyaline cartilage become irregular plates. Smooth muscle tissue forms the Trachealis muscle which connect the ends of each tracheal ring in the trachea and extrapulmonary bronchi. Moderate dense fibrous elastic connective tissue seen between adjacent tracheal rings in the trachea and extrapulmonary bronchi Respiratory system Trachea & extra pulmonary ( primary bronchi ) : Respiratory system Bronchioles : As the bronchi branch and become smaller, the cartilage plates become smaller and the mixed glands become fewer. When cartilage and glands have disappeared some entered the bronchioles. At this point, the muscularis is very close to the epithelium, the epithelium is very still pseudostratified ciliated columnar, although it becomes less tall. Goblet cells are still common in large bronchioles, in terminal bronchioles goblet cells are replaced by Clara cells which are tall columnar cells with IV apical secretory granules. The wall of bronchioles consist of smooth muscle fibers Respiratory system Bronchioles : Respiratory system Terminal portion of respiratory tree : The smallest passages of conducting system further branches become involved in gaseous exchange. Each terminal bronchioles is divided to respiratory bronchioles which contain small no. of alveoli in their walls. Respiratory bronchioles epithelia have no goblet cells and consist of ciliated cuboidal cells + Clara cells [Clara cell contain enzymes system which detoxify noxious substances, also act as stem cell and produce one of surfactant component] Respiratory bronchiole divided into several alveolar duct which end by alveolar sac which in turn opens into several alveoli Respiratory system Alveoli : Are sac like invagination’s, it consider as the terminal portion of bronchial tree and responsible for the spongy structure of the lung. The wall lie between 2 neighboring alveoli termed as interalveolar septum which consist of 2 thin squamous epithelial layers between which lie capillaries, elastic and collagen fibers and fibroblast, so alveolar wall consist of : Respiratory system Alveoli : Surface–epithelium consist of cells of 2 types : Type 1 pneumocyte : large squamous cells constitute part at thin gaseous diffusion barrier. Type 2 pneumocyte : rounded shape secret a surface active material called surfactant which reduce surface tension within alveoli, prevent alveolar collapse during expiration Supporting tissue: reticular , collagenous and elastic fibers and occasioned fibroblast Blood vessels: capillaries Respiratory system Alveolar macrophage : Derived from blood monocytes found in alveolar spaces and alveolar septa ,their function is phagocytosis and removal of unwanted materia Respiratory system Bronchi histology Respiratory Bronchi histology Diameter decrease Sac like alveoli a long the wall Epithelium similar to trachea Epithelium ciliated cuboidal Shape & arrangement of cartilage No goblet cell , Clara cell present & smooth muscle are different No Cartilage Cartilage ring become irregular Little Smooth muscle in LP isolated plate No submucosa Smooth muscle in LP are spirally arranged Lymphocyte & lymphoid aggregation in LP