BIOL 235 CHAPTER 21 BLOOD VESSELS HEMODYNAMICS EXAM TOPIC (QUESTIONS AND ANSWERS)

BIOL 235 CHAPTER 21 BLOOD VESSELS HEMODYNAMICS EXAM TOPIC (QUESTIONS AND ANSWERS) Hemodynamics - CORRECT ANSWER-the forces involved in circulating blood throughout the body Tunica Interna (Intima) - CORRECT ANSWER-inner lining of blood vessel and makes direct contact with blood Lumen - CORRECT ANSWER-Interior opening of the vessel Endothelium - CORRECT ANSWER-Innermost layer of tunica interna and is continuous with endocardial layer of the heart, consists of thin layer of flattened cells that are active participants in a variety of vessel-related activites basement membrane - CORRECT ANSWER-second component of tunica interna, lies deep to the endothelium. Provides physical support base for epithelial layer. Provides significant tensile strength but also resilience for stretching and recoil. Regulates molecular movement during tissue repair of blood vessel walls. Internal elastic lamina - CORRECT ANSWER-Outermost part of tunica interna and forms boundary between the turnica interna and tunica media. -Thin sheet of elastic fibers with windowlike openings (looks like swiss cheese) -Openings facilitate diffusion of materials between two layers Tunica Media - CORRECT ANSWER--muscular and connective tissue layer, displays greatest variation among different vessel types -most are a thin layer of smooth muscle cells with lots of elastic fibers -role regulate diameter of lumen Vasoconstriction - CORRECT ANSWER-increase in sympathetic stimulation causing the smooth muscle to contract decreasing the diameter of the lumen Vasodilation - CORRECT ANSWER-when smooth muscle fibers relax causing increase in diameter of the lumen External elastic lamina - CORRECT ANSWER-Separates tunica media from tunica externa, a network of elastic fibers. Tunica externa - CORRECT ANSWER--outer covering of blood vessels -consists of elastic and collagen fibers -contains nerves and tiny blood vessels that supply the tissue of the vessel wall Vasa vasorum - CORRECT ANSWER-small blood vessels that supply blood tot he tissues of the vessels Compliance - CORRECT ANSWER-usually high in arteries, their walls stretch easily or expands without tearing in response to a small increase in pressure Elastic arteries - CORRECT ANSWER-largest in body with largest diameter but their vessel walls are thin. Characterized by well-defined internal and external elastic laminae along with thick tunica media. Pressure reservoir - CORRECT ANSWER-How elastic arteries propel blood onward while the ventricles are relaxing. As blood ejected from the heart, their walls stretch and momentarily store mechanical energy, then the fibers recoil and convert stored energy in the vessel into kinetic energy of the blood. muscular arteries - CORRECT ANSWER--medium sized arteries -tunica media contains more smooth muscle and less elastic fibers -walls are relatively thick and are capable of greater vasoconstriction and vasodilation -well defined internal elastic lamina, thin external elastic lamina -tunica externa thicker than tunica media and contains fibroblasts, collagen fibers and elastic fibers preventing shortening when fiber is cut -no ability to recoil, contracts and maintains partial contraction (muscular tone) distributing arteries - CORRECT ANSWER-muscular arteries because they continue to branch and distribute blood to various organs anastomoses - CORRECT ANSWER-union of two branches of arteries supply same body region -provide alternate routes for blood flow if iti is stopped due to blocked flow collateral circulation - CORRECT ANSWER--alternative route of blood flow through an anastomoses to a body part end arteries - CORRECT ANSWER-arteries that do not anastomose, obstruction interrupts blood supply to the whole organ Arterioles - CORRECT ANSWER--small arteries -regulates the flow of blood into the capillary networks of the body's tissue -wall thickness one half the total vessel diameter -think tunica interna with thin internal elastica lamina that disappears at the terminal end -tunica media is one to two layers of smooth muscle cells with circular orientation in vessel wall metarteriole - CORRECT ANSWER-terminal end of arteriole that tapers toward the capillary junction precapillary sphinchters - CORRECT ANSWER-found at metarteriole-capillary junction, distal most muscle cell that monitors the blood flow into the capillary resistance - CORRECT ANSWER-how arteriole play a role in regulating blood flow from arteries into capillaries. Opposition to blood flow due to friction between blood and the walls of blood vessels, because the blood vessel diameter is smaller, the friction is greater resistance. Capillaries - CORRECT ANSWER-Function: to exchange substances between blood and interstitial fluid. -smallest of blood vessels, connects the arteriole outflow to the venous return. -forms an extensive network that courses through individual cells of the body -lacks a tunica media and tunica externa microcirculation - CORRECT ANSWER-flow of blood from metarteriole through capillaries and into a postcapillary venule capillary bed - CORRECT ANSWER-network of 10-100 capilllaries that arise from a single metaarteriole vasomotion - CORRECT ANSWER-how blood flows intermittently through capillaries due to alternating contraction and relaxation of smooth muscle of metarterioles and the precapillary sphincters. May occur 5-10 times per minute. Due to chemicals released (nitric oxide) thoroughfare channel - CORRECT ANSWER-distal end of the vessel (metarteriole) and has no smooth muscle, resembles a capillary. Provides a direct router for blood from arteriole to a venule, bypassing capillaries Continuous capillary - CORRECT ANSWER-plasma membranes of endothelial cells form a continous tube that is only interrupted by intercellular clefts. Found in CNS, lungs, muscle tissue and the skin Fenestrated capillary - CORRECT ANSWER-plasma membrane has many fenestrations (small holes). Found in kidneys, villi of the small intenstine, choriod plexus of ventricles in brain, ciliary processes of eyes and most endocrine glands. Sinusoid - CORRECT ANSWER-wider and more winding than other capillaries. Endothelial cells have larger fenestrations, incomplete or missing basement membrane. Large intercellular clefts that allow proteins, and/or blood to pass from tissue to bloodstream Portal system - CORRECT ANSWER-When blood flows through two consecutive capillary networks before returning to the heart such as in the hypothalamus-anterior pituitary, the kidneys, and in the liver, what is this called? Venules - CORRECT ANSWER--thin walls do not maintain their shape easily -drain capillary blood, beginning blood flow back to the heart Postcapillary venules - CORRECT ANSWER--Where venules initially receive blood from capillaries. Porous. Function as sites of exchange with the capillaries. Muscular venules - CORRECT ANSWER-When venules have acquired 1-2 layers of smooth muscle after moving away from postcapillary venules. Thicker walls so no exchange can occur. Able to expand and act as a resevoir for large volumes of blood. Veins - CORRECT ANSWER-No structure change among different types -range in size -thin walls -tunica media with little smooth muscle and elastic fibers -tunica externa thickest with collagen and elastic fibers -not designed to withstand high pressure -lumen larger than artery -average bp lower than artery valves - CORRECT ANSWER-found in veins, thin fold of tunica interna that form flaplike cusps, that project back towards the heart preventing backflow of blood vascular sinus or venous sinus - CORRECT ANSWER-vein with a thin endothelial wall that has no smooth muscle to alter its diameter -surrounding dense tissue replaces tunica media and tunica externa in providing support anastomotic veins - CORRECT ANSWER-venous channels where double sets of veins escort arteries and then connect with one another superficial veins - CORRECT ANSWER-subcutaneous layer unaccompanied by parallel arteries deep veins - CORRECT ANSWER-travel between the skeletal muscles blood resevoirs - CORRECT ANSWER-systemic veins and venules that contain a large percentage of the blood volume where blood can be diverted from quickly if the need arises vasoconstriction - CORRECT ANSWER-constriction of veins which reduce the volume of blood in reservoirs allowing a greater blood volume to flow to skeletal muscles. arteries, arterioles, capillaries, venules, veins - CORRECT ANSWER-order the vessels through which blood moves in its passage from the heart to the capillaries and back capillary exchange - CORRECT ANSWER-movement of substances between blood and interstitial fluid diffusion - CORRECT ANSWER--most important -oxygen and nutrients are in higher concentration in blood and diffuse into interstitial fluid, carbon dioxide and wastes are opposite -cross walls of capillary by diffusing through intercellular clefts, fenestrations or through endothelial cells -water soluble substances pass through intercellular clefts or fenestration. Lipid soluble substances may pass directly through the lipid bilayer of the endothelial cell membrane and most plasma membranes and red blood cells cant diffuse as they are too large, except in sinusoids -brain capillaries only allow select substances, are very 'tight' sealed by tight junctions. Blood brain barriers transcytosis - CORRECT ANSWER-substance in blood become enclosed by tiny pinocytic vessels that first enter cells by endocytosis, then move across the cell and exit the other side by exocytosis -mainly for large, lipid insoluble molecules example insulin bulk flow - CORRECT ANSWER-passive process in which large numbers of ions, molecules, or particles in a fluid move together in the same direction. Moves from an area of higher pressure to lower pressure -important for regulation of the relative volumes of blood and interstitial fluid filtration - CORRECT ANSWER--type of bulk flow, pressure driven movement of fluid and solutes from blood capillaries into interstitial fluid reabsorption - CORRECT ANSWER-pressure driven movement (bulk flow) from interstitial fluid into blood capillaries netfiltration pressure - CORRECT ANSWER-balance of blood hydrostatic pressure (pressure generated by pumping action of heart) and interstitial osmotic pressure starling law of the capillaries - CORRECT ANSWER-near equilibrium of the volume of fluid and solutes reabsorbed normally in capillary exchange blood hydrostatic pressure (BHP) - CORRECT ANSWER--35 millimeters of mercury at the arterial end of the capillary and 16mmHg at the venous end -pushes fluid out of capillaries into interstitial fluid interstitial fluid hydrostatic pressure (IFHP) - CORRECT ANSWER-opposing pressure of interstitial fluid -'pushes' fluid from interstitial spaces back into capillaries -equal 0 mmHg edema - CORRECT ANSWER-filtration greatly exceeds diffusion -not detectable until fluid volume has reached 30% of normal -either increased capillary blood pressure cause more fluid to be filtered from capillaries or increased osmotic pressure allowing plasma proteins to escape blood colloid osmotic pressure (BCOP) - CORRECT ANSWER-a force caused by the colloidal suspension of large proteins (blood of plasma proteins) -'pulls' fluid from interstitial spaces into capillaries interstitial fluid osmotic pressure - CORRECT ANSWER-oppose BCOP -pulls fluid out of capillaries into interstitial fluid blood flow - CORRECT ANSWER-volume of blood that flows through any tissue in a given time period (ml/min). Total=cardiac output. CO= heart rate x stroke volume -how it becomes distributed depends on pressure difference that drives the blood flow and resistance to blood flow blood pressure - CORRECT ANSWER-generated by contraction of ventricle, hydrostatic pressure exerted by blood on walls of a blood vessel. Determine by CO, blood volume and vascular resistance. Highest in aorta. Average 110/70 Systolic blood pressure - CORRECT ANSWER-highest pressure attained in arteries during systole Diastolic blood pressure - CORRECT ANSWER-lowest arterial pressure during diastole mean arterial blood pressure (MAP) - CORRECT ANSWER-average blood pressure in arteries. MAP= diastolic + 1/3 (systolic-diastolic) -CO=MAP/R r=resistance MAP= CO xR vascular resistance - CORRECT ANSWER-opposition of blood flow due to friction between blood and walls of blood vessels. Depends on size of blood vessel lumen and blood viscosity and total vessel length Size of lumen - CORRECT ANSWER-smaller the lumen the greater the resistance to blood flow. As arteriole dilate, resistance decreases and bp falls Blood viscosity - CORRECT ANSWER-Depends on ration of red blood cells to plasma, and concentration of proteins in plasma. Higher viscosity higher the resistance Total blood vessel length - CORRECT ANSWER-resistance to blood flow proportional to length of the blood vessel. The longer the blood vessel the greater the resistance. An estimated 650km of additional blood vessels develop for each extra kg of fat systemic vascular resistance - CORRECT ANSWER-refers to all of the vascular resistances offered by systemic blood vessels. A major function of arterioles is to control SVR and blood pressure as well as blood flow by changing their diameters