理论课讲稿范例.doc

.Teaching chapterRespiratory systemTeaching hours2 hoursTeaching purposes And requirements-Understand the structure and function of the trachea. -Recognize the structural elements of the conducting and respiratory portions of the respiratory system. -Identify the branches of the bronchial tree and their relationship to blood and lymph vessels. -Understand the structure and function of the alveolar wall, (as seen in the light and electron microscopes), with special emphasis on the air-blood barrier, surfactant producing cells, and distribution of connective tissue fibers. -Recognize those cell types present in various parts of the respiratory system. -Understand the blood flow through the lungs including bronchial and pulmonary paths.Key and difficult pointsKey :1. Structure features of trachea.2. Two portions and their structures of lungs.:pay more attention to the structure of alveoli, blood-air barrierDifficult points: Two portions and their structures of lungsToolsPPT, multimedia playing.Teaching procedure（一）Basic structure of respiratory system: 5（二）trachea and bronchus 8（三）lung 551、The conducting portion: changes of histological structure of the channnel2、The respiratory portion: 1) respiratory bronchiole：2) alveolar duct：3) alveolar sac：4) alveoli：3、alveolar septum理论课讲稿（范例） 讲 授 内 容注 解一、Basic structure of respiratory system:The respiratory system is uniquely designed to extract oxygen from ambient air and remove waste gases from the body. The respiratory system consists of a conducting portion and a respiratory portion.The conducting portion of the respiratory system includes the nasal cavity, paranasal sinuses, nasopharynx, larynx, trachea, and bronchi. The conducting portion, from the nostrils to the lungs, provides a passageway for air and functions to condition the incoming air, by warming, moistening and cleaning it. The respiratory portion serves to rid the body off carbon dioxide and pick up oxygen. It consists of respiratory bronchioles, alveolar ducts and alveolar sacs. All of these structures bear alveoli, the tiny air sacs in which the gas exchange takes place.二、trachea and bronchusThe trachea is a flexible tube that extends from the larynx into the thorax. Its main function is to act as a conduit for air, but it also helps condition the inspired air. The trachea consists of four layers: a mucosa (epithelium and lamina propria), a submucosa, and an adventitia.1、mucosa：1) epithelium：Pseudostratified ciliated columnar epithelium which brushes debris up and out. The basement membrane of the epithelium appears unusually thick because a large number of collagen fibres are found underneath the actual basement membrane. This epithelial tissue can be destroyed by smoking, but can regenerate if the person stops smoking.However, the epithelial cells are of different heights, there are short basal cells and tall columnar cells, and their nuclei are seen at different levels. This gives the epithelium a stratified appearance. Because it contains tall cells, it is called a pseudostratified, columnar epithelium. There are five types of cells in the tracheal epithelium. Ciliated columnar cell ：The most abundant cell type. These cells have about 300 cilia at their apical surface, and the cilia sweep mucus and the dust it carries in a coordinated fashion from the deepest passageways to the pharynx, to protect the lungs from particulate matter. The cilia appear as a fuzzy line along the top surface of the epithelium. The nuclei of ciliated cells are relatively pale and lie in about the middle of the cell. Goblet cell ：The next most abundant cell type which secretes mucus. The mucinogen granules are found in the cytoplasm at the apical end.These cells secrete mucus, which moistens the epithelial surface and adheres to inhaled particles. Brush cell ：are columnar cells with short microvilli at their apical surface (hence name), and their basal surface is in contact with afferent nerve fibres. They are thought to be sensory receptors. Small granule cell resembles the APUD cells of the gut. The granules of these cells can only be seen with special techniques such as silver staining. They may function in regulating the caliber of airways or blood vessels, or be involved in regulating mucous and serous secretions. Basal cells ：are believed to be reserve cells that can differentiate into other cell types. Basal cells are short, rounded cells with densely staining nuclei which lie in a row close to the basement membrane. 2）lamina propri ： composed of collagenous, elastic, and reticular fibers may harbor accumulations of lymphocytes, which play an important role in safeguarding the body from inhaled pathogenic organisms. There is no muscularis mucosae.2、The submucosa ：The boundary between the mucosa and the submucosa is not obvious. It consists of loose connective tissue with numerous mixed (serous and mucous) glands. Ducts from these glands open toward the lumen. The mixed glands :The serous glands secrete a watery proteinaceous product, while the mucous glands secrete a viscous, heavier product called mucus. 3、The adventitia：a layer of connective tissue that binds the trachea to adjacent structures in the neck and mediastinum. The adventitia contains the cartilaginous rings interconnected by connective tissue. Each ring is composed of hyaline cartilage, appears in the form of the letter C, and is open posteriorly.The open ends are connected by fibroelastic tissue and a band of smooth muscle (trachealis muscle) whose contraction may reduce the tracheal diameter and increase intrathoracic pressure during coughing. 三、lung （一）The conducting portion：As the bronchi branch and become smaller, the cartilage plates become smaller and farther apart and the mixed glands become fewer. When the cartilage and glands have disappeared, you have entered the bronchioles. At this point, the muscularis is very close to the epithelium and the layer of smooth muscle is relatively thicker than in the bronchi . The height of the respiratory epithelium decreases as the diameter of the bronchus gets smaller. The number of goblet cells also decreases as the bronchus becomes smaller.1、Bronchioles are the terminal segments of the conductive portion. At the transition from bronchi to bronchioles the epithelium changes to a ciliated columnarepithelium, but most of the cell types found in the epithelium of other parts of the conductive portion are still present. Because many of the later passageways of the respiratory tree branch into the next section shortly after arising (eg., terminal branching into respiratory bronchioles), sections that are cut even slightly obliquely can show different passageways in one cross-section. For example, the top might be a respiratory bronchiole, while the bottom could be an alveolar duct.2、Terminal bronchiolesAs the (regular) bronchioles branch into smaller and smaller bronchioles, they eventually give rise to terminal bronchioles. Terminal bronchioles represent the last part of the conducting portion of the respiratory tree. In terminal bronchioles, the ciliated pseudostratified epithelium abruptly gives way to simple cuboidal epithelium consisting of Clara cells.Clara cells are secretory: the lipoprotein they secrete prevents luminal adhesion during expiration and inactivates harmful substances.（二）The respiratory portion：The respiratory portion begins when an air sac (alveoli) first arise which appears as an outpocketing of the bronchiole. At this point, the terminal bronchiole has become a respiratory bronchiole.1、respiratory bronchiole：respiratory bronchioles are the first structures that belong to the respiratory portion of the respiratory system. Its wall is very similar to that of a terminal bronchiole, in that it has Clara cells lying almost directly over smooth muscle bundles. Small outpouchings of the walls of the respiratory bronchioles form alveoli, the site of gas exchange. The number of alveoli increases as the respiratory bronchioles continue to divide. They terminate in alveolar ducts. The walls of alveolar ducts consists of entirely of alveoli.2、alveolar duct：alveolar duct which are thin- walled, fibroelastic tubes are lined with a squamous epithelium and possess alveoli that appear as outpockets of the main wall. The main wall of the duct between alveoli contains smooth muscle.3、alveolar sac：The alveolar ducts will branch and terminate in blind-ended alveolar sacs,which composed of a variable number of alveoli .Alveolar sacs consists of spaces (sometimes called atria) surrounded by alveoli which appear as small compartments opening into the alveolar sac4、alveoli：The tiniest bronchioles branch to the alveoli which are tiny, multi-lobed air sacs. The alveoli are the smallest and most numerous subdivisions of the respiratory system.The lung is more like a well-organized sponge. Each alveolus shares its wall with adjacent alveoli. Alveoli cannot collapse individually, only all together 1）pneumocytesEach alveolus is lined by simple squamous epithelium made of two types of cells, type I and type II alveolar cells covered with a thin film of fluid. This coating (pulmonary surfactant) is produced by Type II alveolar cells (also known as great alveolar cells or septal cells). Alveolar type I cells (small alveolar cells or type I pneumocytes) : Most of the surface (about 95%) is lined by type I alveolar cells which are extremely flattened and form the bulk of the surface of the alveolar walls. The shape of the cells is very complex, and they may actually form part of the epithelium on both faces of the alveolar wall.Alveolar type II cells (large alveolar cells ,Great alveolar cells or type II pneumocytes) which are found interspersed among the squamous epithelial cells are are roughly cuboidal cells. They form small bulges on the alveolar walls. Cytologically,these cells resemble typical secretory cells.They have mitochondria,rough endoplasmic reticulum, a well-developed Golgi apparatus, and microvilli on their free apical surface. In histologic sections, they exhibit a characteristic vesicular or foamy cytoplasm. The vacuoles are due to the presence of multilamcllar bodies, and histochemical studies reveal that these bodies, which contain precursors to pulmonary surfactant, are continuously synthesized and released at the apical surface of the cell. Type II cells secrete surfactant, a phospholipid that spreads over the alveolar surfaces to reduce surface tension.Surfactant ： Surfactant aids in keeping the alveoli open by reducing the surface tension of the moist interface between opposing alveolar surfaces, and thus reducing the inspiratory work required in breathing. This prevents the alveoli from collapsing upon expiration.Surfactant also has a bacteriacidal effect. Hyaline membrane disease in newborns has been correlated with insufficient pulmonary surfactant; neonates with this disorder have great difficulty in opening and expanding alveoli so that oxygen and carbon dioxide exchange can take place. The ability to secrete this chemical doesnt develop until around the eighth or ninth month of pregnancy, so there frequently is a problem in premature babies with the lack of surfactant causing the alveoli to stick together when the baby exhales. Then, when the baby inhales again, the stuck alveolar cells tear away from their neighbors. Scar tissue forms at these sites, thus the damage is permanent, and the persons lungs lose some of their elasticity and ability to expand fully. A current “hot” area of research is searching for a suitable replacement surfactant that could be placed into the lungs of premature babies to prevent this damage.2）blood-air barrier： Definition：The barrier betwe