BIOL 2304/ 2101 Human Anatomy CH-19/ Blood Vessels CHAPTER 19 - CARDIOVASCULAR SYSTEM: BLOOD VESSELSOVERALL FUNCTION OF BLOOD VESSELS:HISTOLOGY OF BLOOD VESSEL STRUCTURELumen =Layers of Vessel Wall:tunica interna (intima)endothelium and basement membranetunica mediasmooth muscleelastic c.t.tunica externa (adventitia)fibrous c.t.Elizabeth Maxim & Anikó Szabó Hill 1 of 9BIOL 2304/ 2101 Human Anatomy CH-19/ Blood Vessels TYPES OF BLOOD VESSELS1) arteriescharacteristics elastic muscular 2) arteriolesElizabeth Maxim & Anikó Szabó Hill 2 of 9BIOL 2304/ 2101 Human Anatomy CH-19/ Blood Vessels 3) capillariesno tunica media or externasite of gas & nutrient exchange Types of capillaries:1. Continuous2. Fenestrated3. SinusoidalCapillary Bed:Elizabeth Maxim & Anikó Szabó Hill 3 of 9BIOL 2304/ 2101 Human Anatomy CH-19/ Blood Vessels 4) venules5) veins valvesANASTOMOSISarterialvenousVASA VASORUMElizabeth Maxim & Anikó Szabó Hill 4 of 9BIOL 2304/ 2101 Human Anatomy CH-19/ Blood Vessels ARTERY VEINcarries blood away FROM heart carries blood TO heartstarts at heart ends in heartstarts with two large branches from heart (aorta, pulmonary trunk), gets smaller and smaller, till capillariesstarts with capillaries and gets bigger and bigger, till two large veins at heart (inferior and superior vena cavae)“branches”, ”diverges”, “forks”“joins”, “merges”, “converges”Tunic media is the thickest from:1. either: elastic-elastic arteries2. or: smooth muscle- muscular arteriesTunic externa is the thickest.Wall (the 3 tunics) is thickerWall (the 3 tunics) is thinerLumen is smaller Lumen is largerNo valves Valves!!!Elizabeth Maxim & Anikó Szabó Hill 5 of 9BIOL 2304/ 2101 Human Anatomy CH-19/ Blood Vessels MAJOR CIRCULATORY PATHWAYSa. pulmonary b. systemicc. cerebral (circle of Willis)Elizabeth Maxim & Anikó Szabó Hill 6 of 9BIOL 2304/ 2101 Human Anatomy CH-19/ Blood Vessels d. hepatic portal system Portal-systemic anastomosis:Elizabeth Maxim & Anikó Szabó Hill 7 of 9BIOL 2304/ 2101 Human Anatomy CH-19/ Blood Vessels FETAL CIRCULATION Elizabeth Maxim & Anikó Szabó Hill 8 of 9BIOL 2304/ 2101 Human Anatomy CH-19/ Blood Vessels Clinical connection:1. Varicose veins2. Hemorrhoids3. Arteriosclerosis4. Aneurysm5. Angiosarcoma6. Phlebitis7. Atheroma8. Deep vein thrombosis 9. Carotid endarterectomy 10. Blue babyElizabeth Maxim & Anikó Szabó Hill 9 of