Exam #3 Review TopicsListed below are some of the key topics discussed in class. This is not meant to be a comprehensive review of lessons 9-12 (for that, you should go over your notes). You are ultimately responsible for all of the information that was presented in class.Lesson 9:How are blood vessels organized and classified?Largest blood vessels- attached to heart; they include:1. Pulmonary trunk: carries blood from right ventricle to pulmonary circulation2. Aorta: carries blood from left ventricle to pulmonary circulationSmallest blood vessels- are the capillaries; they have small diameter and a thin wall. Chemicals/gases diffuse across walls. What are the three layers of blood vessels? 1. Tunica Intima (inner layer)a. Includes: the endothelial lining, connective tissue layer, and internal elastic membranei. In arteries, there is a layer of elastic fibers in outer margin of tunica intima.2. Tunica Media (middle layer)a. Contains concentric sheets of smooth muscle in loose connective tissue b. Binds to inner and outer layersc. Has external elastic membrane, which separates tunica media from tunica externa.3. Tunica Externa (outer layer)a. Anchors vessel to adjacent tissues in arteries. Consists of:i. Collagen fibersii. Elastic fibersb. In veins, contains:i. Elastic fibersii. Smooth muscle cellsWhat is the vasa vasorum?“Vessels of vessels.”- Small arteries and veins in walls of large arteries and veins. They are they supply cells of tunica media and tunica externa.What are the similarities and differences between arteries and veins? Arteries and Veins run side by side. Arteries: thicker walls, higher blood pressure, lining doesn’t contract, lining folds, more elastic, collapsed artery has small and rounded lumen (internal space)Veins: lining contracts, have valves, has a large and flat lumenHow does vasoconstriction and vasodilatation affect blood flow?Vasoconstriction: contraction of arterial smooth muscle by the ANS, increases blood pressure.Vasodilatation: relaxation of arterial smooth muscle; it enlarges the lumen.Both affect: 1. Afterload on heart 2. Peripheral blood flow 3. Capillary blood flowWhat are the differences between elastic arteries, muscular arteries, and arterioles? What are these arteries also known as?(From heart to capillaries, arteries change form elastic arteries, to muscular arteries, to arterioles)Elastic arteries- aka Conducting arteries.• Large vessels (ex. Pulmonary trunk and aorta)• Tunica media ahs many elastic fibers and few muscle cells• Elasticity evens out pulse forceo Stretches when ventricles contract, pusing blood into vessel, recoils to normal state when ventricles relax- recoil allows blood to retain pressureMuscular Arteries- aka Distribution arteries.• Are medium-sized (most arteries)• Tunica media has many smooth muscle cellsAtertioles- are small arteries• Have little or no tunica externa• Have thin or incomplete tunica mediaWhat are the properties of capillaries? They are the smallest vessels with thin walls. Microscopic capillary networks permeate all active tissues. Functions: location of all exchange functions of cardiovascular system, and material diffuse between blood and interstitial fluidStructure: NO tunica media or tunica externa, diameter is similar to that of a red blood cell, endothelial tube inside the thin basement membraneWhat are the different types of capillaries and how do their differences account for their different functions?1. Continuous capillaries- have complete endothelial lining• Permit diffusion of water, small solutes, and lipid-soluble materials• Block blood cells and plasma proteins• Specialized continuous capillaries in CNS have very strictpermeability (responsible for the blood-brain barrier)2. Fenestrated capillaries- have pores in endothelial lining• Permit rapid exchange of water and later solutes between plasm and interstitial fluid• Found in: choroid plexus, endocrine organs, kidneys, and intestinal tract3. Sinusoids (sinusoidal capillaries)- have gaps between adjacent endothelial cells• Liver (produce plasma proteins that enter bloodstream)• Spleen• Bone marrow• Endocrine organs• Permit free exchange of water and large plasma proteins between blood and interstitial fluid• Phagocytic cells monitor blood at sinusoids. They engulf damaged red blood cells, pathogens, and other cellular debris.How is blood flow regulated in capillaries? Precapillary sphinctersWhat are the roles of precapillary sphincters, thoroughfare channels, and anastomoses? Precapillary sphincters- smooth muscle cells. Guards entrance to each capillary; opens and closes, causing capillary blood to flow in pulses. Thoroughfare channels- direct capillary connections between arterioles and venules. They are controlled by smooth muscle segments (metarterioles)Anastomoses- direct connections between arterioles and venules. They bypass the capillary bed. What is vasomotion and why is it important to capillary blood flow?Contraction and relaxation cycle of capillary sphincters. It causes blood flow in capillary beds to constantly change routes. It is controlled locally by changing concentrations of chemicals and dissolved gases in interstitial fluid- autoregulation. Since blood is under low pressure in the veins, how does blood move back to the heart? Blood goes back to the heart through veins. Veins are larger in diameter (than arteries) and have thinner walls.Which structures and mechanisms help to move blood back to the heart? (You may have to also refer to lesson 10 to answer this question). What causes varicose veins?• Venules- very small veins; collect blood from capillaries• Medium-sized veins• Large veins• Venous valves- folds of tunica intima that prevent blood from flowing backwards. Compression pushes blood towards the heart. Malfunctioning valves allow blood to pool (varicose veins.)What causes aneurysms?It is caused by a weak spot in elastic fibers. Pressure may rupture vessel if elastic component fails. An aneurysm is a bulge in an arterial wall. Where is the majority of blood located?30-35% of blood volume- in heart, arteries, capillaries60-65% of blood volume- in venous system. (1/3 of venous blood is in the large venous networks of the liver, bone marrow, and skin)What is capacitance and what is the difference between high and low capacitance?The relationship between blood volume in a vessel and it pressure.High capitance- expands easily
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