1. Cardiovascular system Department of Histology and Embryology Medical college in Three Gorges University

2. The circulatory system comprises both the cardiovascular and lymphatic system. The cardiovascular system: heart blood vessels: capillaries arteries viens

3. There are three layers in the wall of the heart : (1)Endocardium:epithelium subepithelial layer subendocardial layer (2)Myocardium: cardiac muscle (3)Epicardium: connective tissue mesothelium Histology of the heart

4. Endocardium 心内膜 It provide smoothing lining for the chambers of the heart

5. endocardium subepithelial layer Purkinje fibers Endocarditis: inflammation which most caused by bacteria

6. Myocardium 心肌膜 myocarditis

7. Pumping action, involuntary like SM

9. Epicardium: the visceral layer of the serous pericardium Epicardium:connective tissue and mesothelium

10. Arteries: Arteries are blood vessels that carry blood away from the heart. 1. Classification of arteries:arteries are of three types: elastic arteries (conduction arteries) muscular arteries( distributing arteries) arterioles

11. 2. Basic structure of arteries: The wall of an arteries is made up of three layers: (1) tunica intima 内膜 : inner layer (a) endothelial lining (b) subendothelial connective tissue (c) internal elastic lamina: a membrane formed by elastic fibers.

12. 2. Tunica media 中膜 : or middle layer,which is outside the tunical intima. The media may consist predominantly of elastic tissue or of smooth muscle.Some connective tissue is usually present. On the outside the media is limited by a membrane formed by elastic fibers.This is the external elastic lamina.

13. 3. Tunica adventitia 外膜 : the outmost layer of arteries. This coat consist of connective tissue in which collagen fibers are prominent. This layer presents undue stretching or distension of the artery.

17. Elastic Arteries: The feature of elastic arteries is the media which have predominently elastic membrane known as fenestrated membrane, or occupy much of the tunica media. Between the elastic membranes there is some loose connective tissue. Some smooth muscle cells may be present.

21. Muscular arteries: Muscular arteries are characterized by a thick tunica media that is composed mostly of smooth muscle cells. The musles is arranged circulary made up mainly of smooth muscle.This muscle is arranged circulary. Between groups of muscle fibers, come connective tissue is present. This may contain some elastic fibers. Vasa vasorum

25. Arterioles When traced distally, muscular arteries progressively decrease in calibre till they have a diameter of about 100 um.They then become continuous with arterioles. The larger or muscular arterioles are 100 to 50 um in diameter.

26. Arterioles less than 50 um in diameter are called terminal arterioles. Muscular arterioles can be distinguished from true arteries: (1) by their small diameter (2) by the fact that they do not have an internal elastic lamina.

27. Veins: The basic structure of veins is similar to that of arteries.The tunica intima, media and adventitia can be disinguished specially in large veins.the structure of veins differs from that of arteries in the following respects: (1) The wall of a vein is distinctly thinner than that of an artery having the same sized lumen.

28. (2) the tunica media contains a much larger quantity of collagen than in arteries. Elastic tissue (3) Vein is easily compressed, usually collapsed (4) In arteries the tunic media is usually thicker than the adventita.In contrast the adventitia of veins is thicker than the media.

31. Capillaries: Arising from the terminal ends of the arterioles are capillaries,which form, by branching and anastomosing,a capillary bed (network ) between the artrioles and the venules. The richness of the capillary network is related to the metabolic activity of the tissue.

32. General structure of capillaries: Capillaries composed of a single layer of endothelial cells, are the smallest blood vessels. The average diameter of a capillary is 8 um. The wall of a capillary is formed essentially by endothelial cells which are lined on the outside by a basal lamina secreted by the endothelial cells.

33. Overlying the basal lamina there may be isolated branching perivascular cell (pericytes) and a delicate network of reticular fibers and cells.

34. Classification of capillaries: (1)Continuous capillaries: The endothelial cell is continuous, no pores or fenestrated in their walls. The basement membrane is completedly. Distribution: connective tissue,muscle, nervous tissue

36. (2) Fenestrated capillaries: fenestrated capillaries possess pores (fenestrate) in their walls that are covered by pore diaphrgms. The pores are 60-80 nm in diameter, ridged by an ultra thin diaphragm. diffusion of substances takes place through the numerous fenestrate in the capillaries wall. Distribution: kindney, small intestine

38. (3) Sinusoidal capillaries: Sinusoidal capillaries or sinusoids may discontinuous endothelial cells and basal lamina and contain many large fenestrate without diaphragms,enhancing exchange between blood and tissue. Distribution: liver and spleen