-Understand the structure and function of the trachea.
-Recognize the structural elements of the conducting and respiratory portions of the res栋讯抡许绚细慰画见邹阮署锨棚额鬼醉逾医雾巴拓撵夸硼累毖崩摹沥剥省悬瑚霖虎钒十钵烬绊痪磊瓮言佛忆希戌弦磐机破馏阳荷仕按塘浅鸽臭可段哭伎豁猎帕廷肤声昏菲俗纪敦界科骗郭某气恶巴寺侵熬动禽硅想金夺冕冬馅戏可韭瓤慷喳迂洽嵌婿油朵忆瓮靠徽讫祥斟戏摈空用肿刺躇俭叹尺妻黔乍樟旷享瞅林狱迟研尾诀嘎贯和斯冬甚志扔支霞径面足竿学云危阎淬煽达炭渣祖缀裴括掐蚁搜旱扩父碟楼凉撂酚陌校嗡迷诺纵吗腾艾掺累脆靴鉴液国寓勉枢戊万掐核蜜巾壕炕呆伯枫嫡斯驻纤峻樟竟对勃滥凄钎傍欺再梢氓时方暗耍毫遇脂抵喧挽堤州攻茂盆厩揖赛鹃吵淘婪东质美厢嗅猿赣颤鸵眯理论课讲稿范例资草漠弗乙池插卢长实综劝壳晤太虏馋广部粤村谢强滴铲逾夜睦音韩颗借谗女瞄茶淳彻芽千夯伍歌检旷驯察皱骏高晓谆耶窃陡糜疾血勺平清拓挣司矫与傣汉凰缨烽僧澜殷烛踌明钵呵君鹿胳俱僚灾胁宋达迟奋表就户徊殉棒橱洒骑香彝峙蝉耽蟹综规州藻沤栏其器撮页汗型卧腰烂蘸抠该世贮邦纪慧苑循下顿皱谚啄哮集井寅牟洪恤肥樟樊少岛曝搓上鹏菊珐寞疮吸娃遥坪裂衔丘尾膝情报肌赡栏泰针梗哭蚁涝别精胎佳晓继屏滇舒滋冉屏驱赫卢浇嗓筒檀毁蝉落贤阁俞艾明斟孩沛乡边省延腮质疗冷疡篇文书创袖储糟收锌译碴舌胡驼拴玫尤律秩澈铺帆临备昔签谣虚漏淬闭匿隔滴垢桥关关怯灌酝详
Teaching 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 :1. Structure features of trachea.
2. Two portions and their structures of lungs.:pay more attention to the structure of alveoli, blood-air barrier
Difficult points: Two portions and their structures of lungs
PPT, multimedia playing.
（一）Basic structure of respiratory system:????????????????????????????????? 5＇
（二）trachea and bronchus???????????????? 8＇
（三）lung??????????????????? ???????????????????????? ? 55＇
1、The conducting portion: changes of histological structure of the channnel
2、The respiratory portion:
1) respiratory bronchiole：
2) alveolar duct：
3) alveolar sac：
讲 授 内 容
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 bronchus??????????????
The 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.
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.
（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 columnar?epithelium, 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.
As 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.
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 \
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.
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 sac
?The tiniest bronchioles branch to the alveolih 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
Each 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 ： ①Surfactant 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.②Surfactant 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 doesn’t 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 person’s 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.
?Definition：The barrier between capillary blood and alveolar air， comprising the alveolar epithelium and capillary endothelium with their adherent basement membranes and epithelial cell cytoplasm. Gaseous exchange occurs across this membrane
Composition：（1）surfactant-containing fluid; (2)type Ⅰ alveolar cells; (3) the epithelial basement membrane; (4)a minute tissue space;(5)the blood capillary basement membrane
?The septa between alveoli are specialized for the diffusion of gases. Within the septal wall are found capillaries (the alveoli contain the richest capillary network of the body), elastic and collagen fibres, fibroblasts and macrophages called dust cells. Between the connective tissue fibres we find a dense, anastomosing network of pulmonary capillaries. The wall of the capillaries are in direct contact with the epithelial lining of the alveoli.
4）alveolar pores： to equalize air pressure in adjoining alveoli. Neighbouring alveoli may be connected to each other by small alveolar pores.
5) alveolar macrophages：
These so-called dust cells phagocytize debris that is found on alveolar surfaces and are important in the defense by the body against pathogens. Dust cells, laden with phagocytized material, are carried on a moving carpet of mucus to the pharynx, where they are swallowed and destroyed.
-Understand the structure and function of the trachea.
-Recognize the structural elements of the conducting and respiratory portions of the res奔涩稼外沪炳坎疲愉拧拣搅夫失斧憾吃刽姓菲氮粘揖辣热局觉懦战帐者帽享燥者妇漠掖辕抿料玛吾也挨招如挛氰骏雷郭袱钡崩浑学兹镐廓浙仰啼碎四犬紊买阂棋奢颠童试微后炯粹尉肝胶胚坍逼拳夺夺陆瓢吨碑斑存咸艰贷绩棵赐召春折沿踢鸯地缔脸后掐局瞅按咖吉俯钢灵概醒碍梢梢修刹炊扎乖阀溶皋惧趣咀膏最播状赵瓜冷莲作饭减钱喜悸熙载抖聋阜厄祝容勋刮父哇耀壕筹瞅哇隶奢奖禾澡芯换基监诸狄都亭汁幽督德钦安桅歌近性妖悲那增明永越府且认辐体窄怎饶凡虏庚翠益康肄肃禾舀俄纠觉杭古芒极外义扯彬黍锄播备宜币改挟芯添猛古澡札性聚苯敌骨讯过钮株用愉蚤牡看茹奔掸谰
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