BIOC21H3 Lecture : LECT ON BLOOD circulation
11 Jan 2012
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Y tunica intima: y tunica adventitia: lots of collagen, type 1, some elastic fibres to provide recoil ability. this is the outermost layer of blood vessel, simple diffusion not enough to feed it. So the blood vessel has a secondary blood supply vasa vasorum. veins need this more because carrying oxygen poor blood, nothing really to nourish that tissue. nerve supply to blood vessels as well. Ex: want muscle to contract rapidly to cut off blood flow, and not always used. Come in from tunica adventitia and innervate smooth msuscle. y don t need to innervate all of the smooth muscle, will spread to rest of muscle via gap junctions. Diff from skeletal muscles, because each skeletal muscle fibre is innervated separately. y arteries and sizes. Up to 40 layers for aorta: need 50+layers of tunica media to determine size of artery. 2-10 mm (10-20 layers of cell), muscular arteries: small arteries 0. 1-2mm in diameter.
