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APHY 102 Exam 2b
Cardiovascular System - The Blood Vessels
| Question | Answer |
|---|---|
| is blood carried in an open or closed system of vessels? | closed |
| where does the blood system begin and end? | the heart |
| what are the 3 major types of blood vessels? | arteries, capillaries, veins |
| as a rule, which vessels carry blood away from the heart? toward? | arteries; veins -- the oxygenation is reversed at pulmonary arteries/veins |
| which vessels directly serve cellular needs by making contact with tissue cells? | capillaries |
| which cellular needs do capillaries serve? | oxygen loading, carbon dioxide removal, glucose, et cetera |
| what is the generalized structure of arteries and veins? | arteries and veins are both composed of 3 tunics - tunica interna/intima, tunica media, tunica externa, all surrounding the lumen |
| which is the endothelial layer that lines the lumen of all vessels? | tunica interna |
| true or false, in vessels larger than 1 mm, a subendothelial connective tissue basement membrane is present | true |
| which tunic controls vasocontriction/vasodilation of vessels (regulated by SNS)? | tunica media |
| which is the smooth muscle and elastic fiber layer of a vessel, regulated by sympathetic nervous system? | tunica media |
| which is the structure of a blood vessel that has collagen fibers that protect and reinforce vessels on the outside of them? | tunica externa aka tunica adventitia |
| the larger arteries & veins have vasa vasora. what are these? | networks of microvessels that supply blood and nutrients to the walls of large arteries and veins, primarily tunica externa (adventitia) |
| what is the generalized structure of capillaries? | capillaries are composed of simple squamous endothelium with sparse basal lamina |
| which type of blood vessel among the three is unique by having valves? | veins |
| why are arteries thicker than veins? | they have to accommodate higher pressure than veins |
| valves in veins have no papillary muscles or chordae tendineae. is this more similar to semilunar valves or atrioventricular valves? | semilunar valves |
| what are the 3 types of arteries? | elastic (conducting), muscular, and arterioles |
| structurally, which are the arteries that are thick-walled and near the heart? | elastic (conducting) arteries |
| what class of artery are the aorta and its major branches? | elastic (conducting) arteries |
| what are the characteristics of the elastic (conducting) arteries? | large lumen allow low-resistance conduction of blood; contain elastin in all 3 tunics; withstand and smooth out large blood pressure fluctuations |
| describe muscular arteries | distal to elastic arteries, deliver blood to body organs; have thick tunica media(!) with more smooth muscle; active in vasoconstriction |
| which type of artery is active in vasoconstriction? | muscular arteries |
| which type of artery has a thick tunica media, with more smooth muscle? | muscular arteries |
| which type of artery is the smallest type of artery (not blood vessels as a whole)? | arterioles |
| which type of artery is associated most with capillaries? | arterioles |
| true or false, elastic arteries have the greatest control over blood pressure as a whole | false, that would be arterioles |
| true or false, arterioles lead to capillary beds | true |
| which structure controls flow into capillary beds via vasodilation and constriction | arterioles (although muscular arteries are active in vasoconstriction too) |
| what are the smallest blood vessels overall? | capillaries |
| what do capillary walls consist of? | just a thin tunica interna, one cell thick, allowing only a single RBC to pass at at time |
| what are the 3 structural types of capillaries? | continuous, fenestrated, sinusoids |
| what characterizes a continuous capillary? | uninterrupted endothelial lining |
| where are continuous capillaries found? | skin, muscles, blood-brain barrier (where astrocytes live) |
| what characterizes fenestrated capillaries? | endothelial lining with pores (fenestrations) |
| where are fenestrated capillaries found? | in glomerulus of kidney |
| what characterizes sinusoid capillaries? | highly leaky capillaries with slow blood flow |
| where are sinusoids found? | these capillaries are found in liver, bone marrow, lymphatic tissue |
| what is it called when you have a microcirculation of interwoven networks of capillaries, and what do they consist of? | capillary beds consist of vascular shunts and true capillaries |
| what are vascular shunts? | called a metarteriole-thoroughfare channel that connects an arteriole directly with a postcapillary venule |
| what are true capillaries? | 10 to 100 per capillary bed, capillaries branch off the metarteriole and return to the thoroughfare channel at the distal end of the bed |
| which capillary structures branch to exchange, and which bypass? | true capillaries; shunts |
| capillaries have cuffs of smooth muscle that surround each true capillary. these also regulate blood flow into the capillary. what are these cuffs called? | precapillary sphincters |
| capillary blood flow is regulated by what two things? | vasomotor nerves and local chemical conditions |
| when precapillary sphincters are closed, what happens? | blood is forced to bypass the capillary network through a shunt directly into venules, reducing local tissue perfusion, lowering nutrient/oxygen delivery, and allowing blood to be redirected to areas that need it |
| true or false, terminal arterioles go through a capillary bed to a (postcapillary for example) venule | true |
| what is it called when capillary beds unite? when venules unite? | venules; veins |
| from what structure do capillary beds diverge? | terminal arterioles |
| what function do venules have? | allow fluids and WBCs to pass from the bloodstream to tissues |
| what are postcapillary venules and what are they composed of? | they are the smallest venules and are composed of endothelium and a few pericytes, which large venules have one or two layers of smooth muscle (tunica media) |
| what are capacitance vessels? | another way to describe veins... referring primarily to veins and venules, which are highly distensible, thin-walled vessels that store the majority (approx. 60–70% aka two-thirds) of the body's blood volume at low pressure. act as blood reservoirs |
| which has lower blood pressure, veins or arteries? (which oozes when ut and which spurts?) | veins have much lower BP and ooze when cut |
| what two adaptations do veins have to return blood to the heart? | large-diameter lumens, which offer little resistance to flow; valves (resembling semilunar heart valves), which prevent backflow of blood |
| what are venous sinuses? | specialized, flattened veins with extremely thin walls (e.g. coronary sinus of the heart and dural sinuses of the brain) |
| what is a vascular anastomosis? | vascular anastomoses are merging blood vessels, more common in veins than arteries, that provide alternate pathways (collateral channels) for blood -- if one branch is blocked, collateral channel can supply an area |
| what are examples of anastomoses? | thoroughfare channels are examples of arteriovenous anastomoses; ant. and post. interventricular anastomoses are between arteries in the heart |
| what is the flow pathway between vascular components? | from heart to artery to arteriole to capillary to venule to vein back to heart |
| what is blood pressure? | force per unit area exerted on the wall of a blood vessel by its contained blood |
| how is blood pressure measured? | mmHg (millimeters of mercury), measured in reference to systemic ARTERIAL blood pressure in large arteries near the heart |
| what provides the driving force that keeps blood moving from higher to lower pressure areas? | the differences in BP within the vascular system |
| what is resistance? | opposition to flow--a measure of the amount of friction blood encounters |
| where is resistance usually encountered, the pulmonic circulation or systemic circulation? | systemic circulation, and it's referred to as peripheral resistance |
| what does PR stand for with respect to the heart? | peripheral resistance |
| what are the 3 important sources of resistance, and which has the most impact on resistance and flow? | out of blood viscosity, total blood vessel length, and blood vessel diameter, diameter has most impact on resistance/flow because the vascular system actively changes diameter of blood vessels |
| of the 3 sources of resistance, which 2 remain relatively constant? | blood viscosity and blood vessel length; versus, vessel diameter changes are frequent and significantly alter peripheral resistance |
| what kind of proportional relationship does resistance have with vessel radius? | inverse relationship. the bigger diameter is, the less the resistance |
| why are small-diameter arterioles the major determinants of peripheral resistance? | because of their narrow, highly muscular walls that can significantly alter resistance to blood flow through vasoconstriction and vasodilation |
| if the difference in blood pressure between two points increases, what happens to blood flow--does it speed up or decrease? | speeds up; directly proportional relationship |
| which relationship does blood flow have that is inversely proportional? | the relationship to resistance. if resistance increases, blood flow decreases |
| which is more important in influencing local blood pressure, (1) resistance or (2) difference in blood pressure between two points? (separate from question about altering BP) | resistance |
| as blood moves along its pressure gradient from high to low, why does pressure result in the first place? (easy, don't overthink it) | pressure results when flow is opposed by resistance |
| where is systemic pressure highest? lowest? | highest in the aorta, lowerst in the right atrium |
| on a graph, where does the steepest change in blood pressure occur? | arterioles (Fig. 18.5) |
| what factors of the arteries does arterial BP reflect? | their elasticity/compliance/distensibility, and the amount of blood forced into them at a given time (volume inside container) |
| what does it mean that BP in elastic arteries is pulsatile? | it means the blood pressure in those arteries near the heart rises and falls with each cardiac cycle |
| what are the 4 types of arterial blood pressure? | systolic, diastolic, pulse, and mean arterial pressure (MAP) |
| which kind of pressure is exerted on arterial walls during ventricular contraction? | systolic |
| which kind of pressure is exerted on arterial walls during ventricular relaxation? | diastolic |
| what type of arterial pressure is the lowest level of arterial pressure? | diastolic |
| what is the pressure found by taking the difference between systolic and diastolic pressure? | pulse pressure |
| how do you find mean arterial pressure (MAP)? | take diastolic pressure and add 1/3 pulse pressure |
| what is the type of pressure that propels the blood to the tissues? | mean arterial pressure (MAP) |
| what is the range of blood pressure in capillaries in mmHg? | 20 to 40 mmHg |
| why is low capillary pressure desirable? | high BP would rupture fragile, thin-walled capillaries |
| true or false, low BP is insufficient to force filtrate into interstitial space and distribute nutrients, gases, and hormones between blood and tissues | false, it is sufficient |
| which type of blood pressure is NOT pulsatile? | venous BP--it is steady and changes little during cardiac cycle |
| true or false, the pressure gradient in the venous system is about 75 mmHg | false, it's low, about 20 mmHg |
| why does venous blood pressure need help and what 2 "pumps" aid it? | alone it's too low to promote adequate blood return, so the respiratory "pump" and muscular "pump" help venous return |
| what is the respiratory "pump"? | pressure changes are created during breathing that suck blood toward the heart by creating lower pressure in the thoracic cavity and then squeezing local veins |
| what is the muscular "pump"? | the contraction of skeletal muscles that "milk" blood toward the heart |
| what prevents backflow during venous return? | veins' valves |
| what part of the brain supervises blood pressure? | medulla oblongata (Simersong, hit it!) |
| what requires cooperation of the blood vessels with the heart and kidneys? | maintaining blood pressure |
| what are the 2 important ways to ALTER blood pressure? | alter amount of blood in the vascular container and alter the size of the vascular container (vasodilation/vasoconstriction) |
| what 3 factors influence blood pressure? | cardiac output (CO), peripheral resistance (PR), blood volume (all direct proportional relationships--as one increases, so does BP) |
| what is the formula for cardiac output? | stroke volume x heart rate (CO = SV * HR) |
| true or false, cardiac output is independent of venous return and neural (sympathetic) hormonal controls | false, CO is determined by venous return |
| what is resting heart rate controlled by? | the cardioinhibitory center via the vagus nerves (cranial nerves X) |
| under stress, the cardioacceleratory center does what? | increases heart rate and stroke volume |
| what two things do neural controls change to alter peripheral resistance? | alter blood distribution in response to demands and maintain MAP by altering blood vessel diameter |
| neural controls are short-term mechanisms. they operate via what? | reflex arcs |
| what reflex arcs are involved in the short-term neural controls of cardiac output? | baroreceptors (pressure sensors in aortic arch and carotid arteries), vasomotor centers and vasomotor fibers, vascular smooth muscle |
| what is a vasomotor center? | a cluster of sympathetic neurons in the medulla that oversees changes in blood vessel diameter. maintains blood vessel tone by innervating smooth muscles of esp. arterioles |
| for our purposes, which autonomic nervous system affects vasomotor activity? | sympathetic nervous system |
| if increased, sympathetic activity causes what? | vasoconstriction and rise in BP |
| if decreased, sympathetic activity causes what? | BP to decline to basal levels |
| (recognize for multiple choice) vasomotor activity is modified by what 5 things? | baroreceptors (pressure-sensitive), chemoreceptors (O2, CO2, and H+ sensitive), higher brain centers, bloodborne chemicals, and hormones |
| when baroreceptor-initiated reflexes are activated, increasing BP stimulates the cardioinhibitory center to do what? | increase vessel diameter (decrease resistance and BP), and decrease heart rate, cardiac output, peripheral resistance, and blood pressure |
| declining blood pressure stimulates the cardioacceleratory center and vasomotor center both to do what? | increase cardiac output and peripheral resistance |
| is renal regulation a short-term mechanism or long-term? | long term |
| how do the kidneys control blood pressure? by altering what? | blood volume via water elimination or retention (also via the renin-angiotension system) |
| what are the vital signs? | pulse and blood pressure, along with respiratory rate and body temperature |
| what is pulse? | pressure wave caused by the expansion and recoil of elastic arteries (radial artery at wrist is routinely used) |
| true or false, efficiency of the circulation can be assessed by taking pulse and blood pressure measurements | true |
| list the 9 places palpated pulse can be taken (all of these are arteries!) | temporal, facial, common carotid, brachial, radial, femoral, popliteal, posterior tibial, dorsalis pedis |
| how is systemic arterial BP measured? and is it indirect or direct? | auscultatory method is used to measure BP indirectly |
| what is the fancy name for the BP cuff? | sphygmomanometer |
| what are the steps for measuring blood pressure? (1) | pressure is increased in the cuff till it is greater than systolic pressure in the brachial artery |
| what are the steps for measuring blood pressure? (2) | pressure is released slowly and examiner listens with a stethoscope |
| what are the steps for measuring blood pressure? (3) | first sound heard is recorded as the systolic pressure (Korotkoff sound(s)) |
| what are the steps for measuring blood pressure? (4) | the pressure when sound disappears is recorded as the diastolic pressure |
| what numbers indicate low BP (hypotension)? | when systolic pressure is below 100 mmHg |
| what numbers indicate high BP (hypertension)? | when sustained elevated arterial pressure is 140/90 or higher (emphasis on sustained--transient elevations are normal caused by stresses) |
| chronic hypertensive blood pressure can cause what? | heart failure, vascular disease, renal failure, and stroke |
| what is tissue perfusion? | getting blood into tissues |
| tissue perfusion is involved in what 4 processes? | delivery of O2 and nutrients to/removal of wastes from tissue cells, gas exchange in lungs, absorption of nutrients from the digestive tract, urine formation by kidneys |
| true or false, blood flow is precisely the right amount to provide proper tissue function | true |
| what is angiogenesis? | growth of blood vessels -- is a form of long-term regulation |
| in what 4 conditions does angiogenesis take place? | as the number of vessels to a region increases, when existing vessels enlarge, when a heart vessel becomes partly occluded, routinely in people in high altitudes where O2 content of air is low |
| resting blood flow in muscles is regulated by myogenic and general neural mechanisms in reponse to what? | oxygen and carbon dioxide levels |
| what is hyperemia? | presence of an excess of blood within the blood vessels of a specific organ or part of the body. not a disease itself but a physiological response or symptom of underlying condition |
| hyperemia can amount to how much during exercise? | skeletal muscle blood flow can increase tenfold or more during physical activity as vasodilation occurs |
| what is resting muscle blood flow regulated by? | myogenic and general neural mechanisms |
| true or false? blood flow to the brain is constant | true, neurons are intolerant of ischemia |
| how does brain tissue react to declines in pH? (metabolic controls!) | brain tissue is extremely sensitive to declines in pH, so increased carbon dioxide causes marked vasodilation |
| how do myogenic controls protect brain from damaging changes in BP? | decreases in MAP (mean arterial pressure) cause cerebral vessels to dilate to ensure adequate perfusion; increases in MAP cause cerebral vessels to constrict |
| what is a circumstance under which the brain can regulate its own blood flow? | for example, ischemia caused by a tumor |
| true or false, the brain is resilient under extreme systemic pressure changes | false, it is vulnerable. for example, MAP below 60 mmHg can cause syncope (fainting) and above 160 can result in cerebral edema |
| skin is fairly tolerant of a lack of vascularization. but blood flow through skin does what 3 things? | supplies nutrients to cells in response to oxygen need, helps maintain body temperature, and provides a blood reservoir |
| what does the body do to regulate temperature, whether in response to heat exposure, fever, or vigorous exercise? | hypothalamic(!) signals reduce vasomotor stimulation of the skin vessels, sympathetic input is decreased; vessels vasodilate (relax), increasing cutaneous blood flow; heat radiates from the skin |
| what about temperature decreasing? what does the body do in response? | blood is shunted to deeper, more vital organs to preserve heat (may result in hypothermia in extremities in winter) |
| true or false, the pulmonary circulation pathway is long | false, it is short |
| how much lower are arteries/arterioles' arterial pressure than in the systemic circulation? | 24/8 mmHg versus 120/80 mmHg |
| small vessel coronary circulation is influenced by what two factors? | aortic pressure and the pumping activity of the ventricles |
| what 3 things are of note that happen during ventricular systole? | coronary vessels compress, myocardial blood flow ceases, store myoglobin supplies sufficient oxygen during temporary cessation of blood flow |
| braintwister: during ventricular diastole, oxygen and nutrients are carried to the heart | yup, that's all |
| at rest, blood flow through heart may be controlled by myogenic mechanism, but during strenuous exercise, what 3 things happen of note? | coronary vessels dilate in response to CO2; blood flow may increase 3-4 times; blood flow remains constant despite wide variation in coronary perfusion pressure |
| what 4 things are exchanged at capillaries? | oxygen, carbon dioxide, nutrients, and metabolic wastes diffuse between the blood and interstitial fluid along concentration gradients |
| be more specific about the nutrients and metabolic wastes at exchanged at capillaries. which types pass through clefts and fenestrations, and which through endothelial membranes? | water-soluble solutes pass through clefts and fenestrations, lipid-soluble molecules diffuse directly through endothelial membranes, large substances pass through transport via vesicles or caveolae |
| what is circulatory shock? | any condition in which blood vessels are inadequately filled and blood cannot circulate normally, resulting in inadequate blood flow to meet tissue needs |
| what are the 3 types of circulatory shock? | hypovolemic, vascular, cardiogenic shock |
| what is hypovolemic shock? | circulatory shock resulting from large-scale blood loss |
| what is vascular shock? | poor circulation resulting from extreme vasodilation like if SNS cuts out and blood goes to bottom half of body |
| what is cardiogenic shock? | circulatory shock at fault with the heart because it cannot sustain adequate circulation (such as because of heart attack (MI)) |
| what are the two distinct circulations that the vascular system has? | pulmonary circulation and systemic circulation |
| how do arteries and veins differ in delivery? | arteries have blood pumped into a single systemic artery (the aorta) while venous return occurs via the superior and inferior venae cavae and the coronary sinus |
| how do arteries and veins differ in location? | arteries are deep and protected by tissue, veins are both deep and superficial |
| how do arteries and veins differ in pathways? | artery pathways are clear and well-defined, veins are more variable |
| how do arteries and veins differ in supply/drainage? | arteries have predictable supply ("stereotyped"), veins network contains unusual structures like dural sinuses and hepatic portal circulation |
| what is the arterial pathway in the body? | carotid and vertebral arteries → subclavian → axillary → brachial → radial/ulnar → torso/organs: renal (kidneys), celiac, and mesenteric (digestion) → legs: iliac → femoral → popliteal → tibial |
| what is the general venous pathway in the body? | capillaries (waste exchange) → venules (small collectors) → veins (major conduits) → vena cava (The main "drains" to the heart) |
| what is the venous pathway at the brain/head? | jugular veins → brachiocephalic vein → superior vena cava |
| what is the venous pathway at the arms from distal to proximal? | arms: radial/ulnar veins → brachial vein → axillary vein → subclavian vein → superior vena cava |
| what is the venous pathway from the lower body? | tibial veins → popliteal vein → femoral vein → external iliac vein → inferior vena cava |
| what is the venous pathway from the organs? | renal (kidneys) / hepatic (liver) veins → inferior vena cava |
| what is the pulmonary circuit, starting at the lungs? this is the only part of the venous system carrying oxygen-rich blood | lungs → pulmonary veins → left atrium of heart |
| what is the venous pathway at the gastrointestinal tract? | GI tract → hepatic portal vein → liver → hepatic vein → inferior vena cava |
| how can the circle of Willis avoid a stroke? | the Circle of Willis (CoW) can often avoid or minimize the severity of a stroke by providing collateral circulation—a built-in backup system for blood flow to the brain |
| what are the 3 branches of the aortic arch? | brachiocephalic trunk, left common carotid artery, and left subclavian artery |
| true or false, the CSF drains from the brain via the jugular vein | true |
| what are the 3 major veins of the arm? | cephalic, basilic, mediancubital |
| the great saphenous vein (GSV) travels the entire length of the lower limb and is the longest vein in the human body. where does it start and end? | originating at the dorsal venous arch of the foot and ascending the medial (inner) side of the ankle, leg, and thigh before draining into the femoral vein near the groin |
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