Circulatory system
General outline Heart Arteries Capillaries veins Blood vascular system Lymphatic capillaries Lymphatic vessel Lymphatic ducts Lymphatic vascular system
Capillaries A single layer of endothelial cells basement membrane A few connective tissue (pericytes) LM Continuous capillary Fenestrated capillary Sinusoid EM
Capillaries Continuous C. Fenestrated C. Sinusoid
Continuous capillary: distributed in muscle tissue, brain, lung and connective tissue, etc. endothelial cell: large number of pinocytotic vesicles, no pores, exist cell junctions between the endothelia basement membrane: integrity
Continuous capillary
Fenestrated capillary: distributed in the kidney glomerulus, mucosa of gastrointestine, some endocrine glands endothelial cells: present abundant pores, have or haven’t diaphragm on them basement membrane: continuous
Fenestrated capillary
Sinusoid: distributed in liver, spleen, and some endocrine glands a greatly enlarged diameter endothelial cell: intercellular clefts are large between cells, many pores without diaphragm absence of a continuous basement membrane
Sinusoid
Artery transport blood from heart to capillaries according to their size, structure and function Large artery Medium-sized artery Small artery arteriole are classified
Medium-sized artery: muscular artery Endothelium Subendothelial layer: LCT Internal elastic lamina: clear Tunica intima Tunica media: contain 10~40 layers of circular smooth muscle External elastic lamina LCT: contain vasa vasorum Tunica adventitia
Medium-sized artery
Large artery: elastic artery subendothelial layer is thicker with a few smooth muscles tunica media is thick, contains a lot of circular elastic membrane internal and external elastic lamina are not distinguished tunica adventitia are thiner
Large artery
Small artery: muscular artery and peripheral resistance vessel internal elastic lamina is clear, while external elastic lamina is not distinguished the media contains 3~9 layers of smooth muscles
Vein large lumen, thin wall, irregular internal and external elastic lamina are not clear tunica media is thin, with a few elastic fibers and smooth muscles tunica adventitia is thick some veins have valves
Heart a muscular organ that contracts rhythmically pump blood through the circulatory system
The wall of heart Endothelium Subendothelial layer Subendocardial layer endocardium myocardium: thickest layer, consists of cardiac muscle LCT: contain adipose tissue Methothelium epicardium
Impulse generating and conducting system of the heart: Pacemaker cells: heartbeat generating Purkinje cells (bundle cell): distributed in subendocardial layer, larger than cardiac muscle cells Transitional cells: transmit impulse
Purkinje cell Cardiac cell