Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Chapter 8 Circulatory system Teacher :Huang Ju-en (黄巨恩) Dept.of Histology and Embryology 1.Concepts of organs and systems Organ: composed of four kinds of the tissues in a particular way Types Hollow organs: studied from inside to outside parenchyma Substantial organs: interstitium System: composed of many organs which have relationship with each other in structure and function. 2.Composition of circulatory system Cardiovascular system lymph vascular system lymphatic duct lymphatic vessel lymphatic capillary heart vein artery capillary tissue fluid artery vein heart capillary 一、Composition of blood vessel and their general structures Endothelium Tunica intima Subendothelium Internal elastic M. Tunica media Tunica adventitia 1.Intima (1)Endothelium Distribution、morphology Face the lumen and belong to squamous Model of endothelium of blood vessel WeibelPalade body Fig. Of EM (2)Subendothelial layer Located beneath the endothelium Composed of thinner layer of C.T containing small amount of collagenous fibers,elastic fibers or some smooth muscle (3)Internal elastic membrane Internal elastic membrane is composed of elastic protein and there exist many fenestrations on it. It is wave-like and serve as a border between intima and media of artery. 2. Media Located between Intima and adventitia Thickness depend on different kinds of blood vessels Composition Large A. ——elastic M. medium A. —— Smooth M. Function Dilate and retract blood vessels, Maintain tension of blood vessels 3.Adventitia Distribution outermost、 Thickness thicker Composition L.C.T containing fibroblast, collagenous F. , elastic F. and external elastic membrane adventitia Heart The wall is thickest and consist of largely cardiac muscle nucleus Intercalated disc Cardiac muscular fiber heart 1. The structure of heart wall endocardium:endothelium, subendothelial layer, subendocardial layer. myocardium:three layers are divided roughly, cardiac muscle arrange spirally. epicardium:plasma membrane, mesothelium on the surface Intercalated disc Mesothelium Adipose tissue Tunica adventitia 2.Heart conducting system Definition:This system is composed of specific cardiac muscle fibers that can generate and conduct impulses to all parts of the heart, making heart contraction in rhythm. Types of cell:pacemaker cell, transitional cell, Purkinje fiber. ※cardiac skeleton── A supporting structure, locating between atrial muscle and ventricular muscle and consisting of DCT. It is a frame of heart and provide a attachment for cardiac muscle and cardiac valve. ※cardiac valve──The thin-scalloped structure, formed by endocardium protruding into cavity of heart. The core of dense connective tissue Endothelium Endocardium Valve Arteries(Artery,A) 1. Grade: large A:Φ>10 mm medium-sized A:Φ1─10mm small A:Φ0.3─1mm arteriole:Φ<0.3 mm. 2. Characteristics of various arteries : large A(elastic A): Conducting A. Medium-sized A (muscular A): Distributing A. Features of large A (1) Subendothelial layer: is thicker. There not only are many layers of internal elastic membrane outsides, but also confused together with elastic membrane of middle membrane. As a result, layering of large A are not as clear as medium-size A. (2) Middle tunic: consist mainly of elastic membrane of 40~70 layers, with occasional smooth muscle cells, elastic fibers and collagen fibers among elastic membranes. Major components of ground substance are chondroitin sulfate. (3) External tunic:This is a thin layer of connective tissue and there is not obvious border with enveloping connective tissue. External elastic membrane is not obvious. Intima Elastic M. Smooth Muscle Media Adventitia Large Artery external tunic Middle tunic Features of medium-side A (1)Layering clearly. internal elastic membrane is integrate (2)Middle tunic consist of smooth muscle of 10~40 layers, intermixing with elastic fibers, collagenous fibers and ground substance. (3)Thickness of external tunic equal middle and often there is obvious external elastic membrane between two tunic. 3.Small A: They are also muscular A but layering is not clear. Smooth muscle is small. There is no external elastic membrane. 4.Arteriole: layering is not more clear. There is only one or two layers of smooth muscle Arteriole Small A. Small V Capillary (Cap.) 1.Distributions:broadly and have a relation with metabolism. Size:Cap. generally is 6~8 μm, but some sinusoid can reach 40 μm in diameter. 2.General structures: ①endothelia ②basal membrane ③pericytes:The flat-thin cells with processes between endothelium and basal membrane. ④small amounts of connective tissues 3.Classifications and their EM structures: continuous cap.: fenestrated cap.: sinusoid(sinusoidal cap., discontinuous cap.): 4.The structural bases of substance interchange of cap.: (1)Larger square, thin vascular wall, short distance with surrounding cells. (2)O2 、CO2 and lipid-soluble substances can penetrate the walls of cap. directly. (3)liquid and macromolecule can pass through endothelial pores. (4)pinocytotic vesicles can transport liquid. (5)intercellular space facilitate more easily elements to pass through. (6)basal membrane make small molecular substances filtrate readily , so disintegrate basal membrane or no is easier to material exchanges. 5. Capillary permeability: The ability of substances passing through capillary. Classifications and ultrastrutural feature of Cap. continuous cap. fenestrated cap. sinusoid Pore Pinocytotic vesicle pinocytotic (plasmalemmal) vesicles Endothelium Intercellular space RBC Basal membrane pore sinusoid Vein, V 1.structural characteristics: ①internal and external elastic membrane both are unclear ②The thickness of external tunic> middle tunic ③large and irregular lumens, thin walls. 2.Vein valves: Internal tunic of veins (their diameter usually are over 2 mm) protrude into lumens and form pleats , in the center of which connective tissue containing elastic fibers exist, but endothelia overlap on the surfaces. 3.Microcirculation 1.Definition:The blood circulation of micro-small blood vessels between arterioles and venules 2.Compositions:arterioles, precapillary arterioles, metaarterioles, true capillaries, short cuts, arteriovenous anastomosis and venules. Questions 1. By comparison, what are the same and different items among larger, medium-side and small arteries in the structures of vessel walls? Try to describe the relationships between the structures and functions of blood vessels 2. How to distinguish arteries and veins under LM? 3. How to distinguish the surface of endocardium from that of epicardium under LM? 4. Try to describe the general characteristics of structures of capillaries. What are structural and functional features for each kind of capillaries respectively? Good-bye!