BSC 2086 1st Edition Exam 3 Study Guide 1 How are blood vessels organized and classified What are the three layers of blood vessels What is the vasa vasorum a Classified by size and histological organization i Size 1 Largest blood vessels are connected to the heart a Pulmonary trunk carries blood into pulmonary circulation from the right ventricle b Aorta carries blood into systemic circulation from the left ventricle 2 Capillaries are the smallest blood vessels a Exchange nutrients chemicals gases and waste across walls ii Types 1 Arteries carry blood away from heart 2 Arterioles smallest branches of arteries 3 Capillaries smallest blood vessels which allow for exchange between blood and interstitial fluid 4 Venules get blood from the capillaries 5 Veins return blood to the heart b Three layers i Tunica intima 1 Inner layer 2 Includes a Endothelial lining b Connective tissue layer c Internal elastic membrane i In the arteries this layer is found in the outer margin of the tunica intima ii Tunica media 1 Middle layer 2 Concentric sheets of smooth muscle in the connective tissue a Smooth muscles under autonomic control 3 Binds to both inner and outer layers 4 External elastic membrane a Separates the tunica media from the tunica externa iii Tunica externa 1 Outer layer 2 Attaches vessel to adjacent tissues in the arteries a Collagen and elastic fibers 3 In veins it contains elastic fibers and smooth muscle cells 4 Vasa vasorum a Vessels of vessels b Small arteries and veins which are found in the walls of large arteries and veins c Supply the cells of the tunica media and externa 2 What are the similarities and differences between arteries and veins How does vasoconstriction and vasodilation affect blood flow a Arteries i Usually round ii Thick wall made up mostly of tunica media 1 Dominated by smooth muscle cells and elastic fibers iii Higher blood pressure iv Collapsed artery has small round lumen internal space v Lining is able to fold and is more elastic 1 Able to absorb pressure waves that come with each heart beat due to their elasticity b Veins i Flattened or collapsed with a thin wall ii Absent internal and external elastic membrane iii Large flat lumen iv Lining of the vein will contract unlike the lining of the artery v Have valves c Similarity run side by side d Vasoconstriction contraction of smooth muscle by the ANS which restricts the flow of blood by making the vessel smaller e Vasodilation relaxation of smooth muscle which enlarges the lumen allowing more blood to flow through the vessel f Affects of vasoconstriction and vasodilation i Afterload on heart 1 Resistance against the flow of blood stroke volume out of the heart ii Peripheral blood pressure iii Capillary blood flow 1 Amount of blood that actually flows into the capillaries 3 What are the differences between elastic arteries muscular arteries and arterioles What are these arteries also known as a Elastic arteries i Large vessels like the pulmonary trunk and the aorta ii Tunica media 1 Few muscle cells 2 A lot of elastic fibers iii Elasticity is able to even out pulse force 1 Stretches when the ventricles contract and pushes blood into vessel 2 Recoils back to normal state when ventricles relax 3 This recoil allows blood to retain pressure b Muscular arteries i Medium sized ii Tunica media is composed of many smooth muscle cells c Arterioles i Small arteries ii Little or no tunica externa iii Thin or incomplete tunica media d Elastic arteries conducting arteries e Muscular arteries distribution arteries f Arterioles small arteries 4 What are the properties of capillaries What are the different types of capillaries and how do their differences account for their different functions a Smallest vessels with thin walls b Function to diffuse materials between interstitial fluid and blood i All exchange functions of the cardiovascular system c Structure i Endothelial tube with a thin basement membrane inside ii Diameter is similar to that of a red blood cell iii NO tunica media or tunica externa d Types i Continuous capillaries 1 Complete endothelial lining 2 Found in all tissues except cartilage and epithelia 3 Functions a Allow diffusion of water small solutes and lipid soluble materials b Block blood cells and plasma proteins c Specialized continuous capillaries in the central nervous system have strict permeability i Responsible for blood brain barrier ii Fenestrated capillaries 1 Pores in endothelial lining 2 Allow rapid exchange of water and large solutes 3 Found in a Endocrine organs b Choroid plexus c Kidneys d Intestinal tract iii Sinusoidal Capillaries 1 Gaps between adjacent endothelial cells 2 Found in a Spleen b Liver make plasma proteins that enter blood c Bone marrow d Endocrine organs 3 Allow free exchange of water and large plasma proteins between blood and interstitial fluid 5 How is blood flow regulated in capillaries What are the roles of precapillary sphincters thoroughfare channels and anastomoses What is vasomotion and why is it important to capillary blood flow a Phagocytic cells monitor blood at the sinusoids i Engulf damaged red blood cells pathogens and wastes b Precapillary sphincter smooth muscle cells i Guard the entrance to each capillary ii Capillary blood flows in pulses due to them opening and closing c Thoroughfare Channels i Direct capillary connections between the arterioles and the venules ii Controlled by metarterioles smooth muscle segments d Collaterals multiple arteries which all contribute to one capillary bed i Allow circulation to continue if one artery is blocked ii Arterial anastomosis 1 Union of 2 collateral arteries iii Arteriovenous anastomoses 1 Direct connectors of arterioles and venules which bypass the capillary bed e Vasomotion i Cycle of relaxation and contraction of capillary sphincters ii Allows the blood flow in the capillary beds to constantly change routes 6 Since blood is under low pressure in the veins how does blood move back to the heart 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 a Compression of the venous valves helps push blood toward the heart without permitting the backflow of blood b Pressures from the systole also push the blood throughout the body and pressure reserve squeezes out excess blood from vessels 7 What causes aneurysms and varicose veins a Aneurysm is a bulge in the arterial wall caused by a weak spot in the elastic fibers i High pressure
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