Vessel-FlowOutline

Vessel-FlowOutline - BIOLOGY 2060 LECTURE NOTES ANATOMY...

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1. Blood vessels a. Tubes through which the heart pumps blood. b. 3 major types of blood vessels: arteries, capillaries, and veins. 2. Arteries a. Take blood away from the heart. b. Branch repeatedly, forming smaller and smaller arteries and eventually the smallest arteries – the arterioles. c. Typically carry oxygenated blood (exception – pulmonary arteries). 3. Capillaries a. Smallest and most numerous vessel type. b. Sites of exchange between blood and tissue fluid. c. Exchange is facilitated by their thinness and vast number (≈ 10 billion). d. “Connect” arteries and veins. 4. Veins a. Take blood toward the heart. b. Converge and join, forming larger and larger vessels. c. Smallest veins are the venules, which receive blood from capillaries. d. Typically carry deoxygenated blood (exception –pulmonary veins). 5. Tunics a. Arteries and veins have 3 basic layers or tunics surrounding their lumen: i. Ttunica interna, tunica media, and tunica externa. b. Capillaries contain only the tunica interna. 6. Tunica interna a. A.k.a. the tunica intima. b. Lines the lumen and consists primarily of endothelium, a simple squamous epithelium underlain by loose connective tissue. c. Provides a smooth surface ideal for fluid flow. 7. Tunica media a. Consists of circularly arranged smooth muscle cells and sheets of the protein elastin. i. Smooth muscle tone is regulated by vasomotor fibers of the sympathetic nervous system, hormones, and local chemicals. ii. Increase in tone leads to vasoconstriction – a decrease in vessel diameter. iii. Decrease in tone leads to vasodilation – an increase in vessel diameter. iv. There is a tonic release of NE onto vascular smooth muscle by vasomotor neurons. v. Increasing NE release causes smooth muscle contraction (vasoconstriction). vi. Decreasing NE release causes smooth muscle relaxation (vasodilation). b. Most prominent layer in arteries. 8. Tunica externa a. A.k.a. tunica adventitia. b. Consists of mostly collagen fibers that protect, reinforce, and support the vessel. c. Most prominent layer in veins. 9. Basic types of arteries: a. Elastic arteries, muscular arteries, and arterioles. 10. Elastic arteries a. A.k.a. conducting arteries. b. Closest to the heart, e.g., the aorta and its major branches (e.g., common iliacs, common carotids). c. Contain a great deal of elastic tissue in all 3 layers. i. Allows them to absorb the pressure associated with each ventricular contraction. ii. Helps produce continuous blood flow even while the heart is in diastole. 11. Muscular arteries a. A.k.a. distributing arteries. b. Primarily involved in regional distribution of blood, i.e., delivery of blood to specific organs (e.g., splenic artery, renal artery). c.
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Vessel-FlowOutline - BIOLOGY 2060 LECTURE NOTES ANATOMY...

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