BIOL 1080 Chapter Notes -Thoracic Cavity, Pulmonary Artery, Pulmonary Circulation
8 Mar 2014
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Document Summary
Blood is carried away from the heart in arteries. Blood is carried towards the heart in veins. Heart-->arteries--> arterioles-->capillaries ( allows exchange of materials between blood and cells) Allows artery to stretch and adapt to pressure changes to keep a relatively even pressure within the artery. Outer layer is sheath of connective tissue containing fibers and collagen. Outer layer adds strength to wall and anchors to tissue. Our pulse is created by this expansion and recoil of arteries. Aneurysm: weakened arterial wall leading to the artery wall swelling outwards. Biggest risk is that the aneurysm will burst or clot. Thin walls to allow substances to move between the blood and fluid outside capillary. Plasma membrane in endothelial cells is selective barrier. Network of capillaries for a particular area are the capillary bed. Precapillary sphincters: valves that open and close capillary beds. Blood flows slower through capillaries because of the small size, but large cross sectional area.
