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104 Cards in this Set
- Front
- Back
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What is a calcium channel blocker and what does it do?
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drug binds the slow calcium channels of heart and decrease the entry of calcium; they decrease the force of contraction
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What is digitalis?
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Na-K pump inhibitor; impairs the Ca-Na exchange. Leads to greater Ca concentration in the SR and inhances contraction
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What receptors does sympathetic activity effect?
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alpha and beta androgenic and M3 skeletal arterioles
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what receptors does parasympathetic activity effect?
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muscarinic cholingeric
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what neurotransmitter is used in the sympathetic activity of the heart?
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norepineprhine
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what transmitter is used in the parasympathetic acitivity of the heart?
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acetylcholine
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Does the SA node or AV node activity cause a faster heart rate?
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SA node (70-160 bpm)
AV node (40-60bpm) |
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What characteristics are influenced in the AV node to increase/decrease heart rate?
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conduction velocity, refractory period, depolarization time
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How does lidocaine work as an antiarrhythmic drug?
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binds to fast Na channels preventing them from opening and counteracting membrane potential formation. Utlimately, raises threshold for potential formation and preventing ectopic pacemakers from firing.
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How do cardiac glycosides work as an antiarrhythmic drug? (digitalis)
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Na/K pump inhibitor, increase parasympathetic activity, allows more Ca than normal in - increases contraction strength
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How do beta androgenic antagonist drugs work as an antiarrythmia drug?
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binds to beta androgenic receptors, preventing their activiation -- blocks sympathetic activity; decreases contractility
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Stroke volume
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SV = EDV - ESV
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What are the major factors of Cardiac Output?
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CO = SV x HR
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How can you increase SV?
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Increase EDV, decrease ESV
Increase contractility, increase compliance, increase preload, decrease afterload |
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How can you increase EDV?
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Increased venous pressure (or atrial pressure), increase preload
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How can you measure L and R ventricualar preload?
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Left side: pulmonary wedge pressure
Right side:cathetar to jugular v to vena cava: when valves are open during diastole ventricle pressure = atrial pressure = venous pressure |
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What is starlings law of the heart?
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increase in preload (increased EDV) causes SV to increase
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What is compliance?
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ease with which walls stretch to accomodate incoming volume
change in volume / change in pressure Non compliant ventricle requires higher preload to reach normal filling |
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How do you measure CO?
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Thermodiluation technique
inject cold saline; indirect propotion blood volume to temperature change |
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What determines EDV?
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preload, compliance, filling time
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What determines ESV?
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contractility, arterial blood pressure (afterload - aortic pressure)
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What is a positive inotrope?
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increases contractility
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What is a negative inotrope?
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Decreases contractility
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What is a positive chronotrope?
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increase HR
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What is a negative chronotrope?
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decreases HR
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What are factors of preload?
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venous/atrial pressure
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What are factors of afterload?
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arterial or venous pressure
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What factors influence preload?
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venous pressure and rate of venous return
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What effects does mitral regurgitation have?
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LA: increased pressure, increased pulmonary pressure, pulmonary edema
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What effects does patent ductus arteriosis have on the heart and circulation?
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LV: increased volume work = hypertrophy
Right side: increased pulmonary pressure = pulmonary edema and increased pressure work on RV = hypertrophy |
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What effects does Mitral stenosis have?
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increased left atrial pressure = hypertrophy and increased pulmonary pressure leading to pulmonary edema
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What is the ejection fraction?
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EF = SV/EDV
assessment of contractility |
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What is Ohm's law?
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Resistance = change in pressure/Flow
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What are factors of resistance?
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Vessel diameter, velocity, density, viscosity
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What is reynold's equation?
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diameter x velocity x denisty/viscosity
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What measurement is considered turbulent flow?
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values greater than 2000
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what is poiseulle's equation?
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R = viscosity x L x 8 / pi x (radius) ^4
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What factor is the most important regarding resistance?
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radius of vessel
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What is the la of laplace?
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T = Pt x r / u
tension, transmural pressure, radius, and vessel wall thickness |
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What is total peripheral resistance?
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perfusion pressure/flow
flow = CO in systemic circ. net resistance of systemic circulation |
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What is mean aortic pressure?
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(BP) = CO x TPR
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What are factors of mean aortic pressure?
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CO, TPR
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What determines arterial pressure?
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cardiac output and total peripheral resistance
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Tell me about arterial pressure in hypertension.
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CO is normal, TPR is increased because of constricted arteries, arterial blood pressure is increased
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Tell me about arterial pressure in severe hemorrhage or dehydration.
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CO decreased, TRP increases above normal, arterial blood pressure is still decreased
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Tell me about arterial pressure in vigorous exercise.
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CO increased, TPR decreased, arterial blood pressure mostly unchanged
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How does arterial pressure stay unchanged during exercise?
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although CO is increased, BV's dilate to decrease TPR keeping arterial pressure
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what determines flow?
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perfusion pressure and vascular resistance
perfusion pressure / resistance |
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What determines flow in the systemic circulation?
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resistance. all organs in systemic circulation have same perfusion pressure; blood flow is result of resistance
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What circulation system has more resistance?
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systemic
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What is ventilation perfusion mismatch?
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more blood flows to ventral portions of lungs due to gravity - mismatch between blood flow and oxygen exhange.
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How does the body fix ventilation perfusion mismatch?
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hypoxic vasoconstriction - shunts blood flow to get more uniform flow/perfusion all around
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What is MAP?
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mean arterial pressure = diastolic pressure + [1/3] pulse pressure
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How does SV affect arterial pulse pressure
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increased SV increases pulse pressure
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how does HR affect arterial pulse pressure
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pulse pressure increases when heart rate decreases
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how does compliance affect arterial pulse pressure
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pulse pressure increases when aortic compliance decreases
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how does TPR affect arterial pulse pressure?
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pulse pressure increases when TPR increases
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how do murmurs affect pulse pressure?
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PDA/aortic regurgiation increase pulse pressure
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How does simultaneous increase in SV and decrease in HR (CO remains the same) affect arterial pulse pressure?
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increase in pulse pressure
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How does increased TPR and decreased compliance affect pulse pressure?
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increases pulse pressure
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What are the factors of Fick's law?
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rate of diffusion depends on concentration difference, area available for diffusion, distance over which diffusion must occur, (diffusion coefficient)
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what is starlings equation?
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18 - hydrostatic pressure difference minus the oncotic pressure difference
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what is responsible for plasma oncotic pressure?
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protein concentration in plasma
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What are the 3 "safety factors" regarding edema?
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interstitial hydrostatic pressure, lymph flow, decrease in insterstitial fluid protein concentration
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Why is lymphatic edema clinically troublesome?
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the only "safety factor" intact is the increased interstitial fluid pressure causing decreased capillary filtration
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What is the intrinsic control mechanism for active hyperemia?
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Increased metabolic rater = increased oxygen consumption and release of waste products. Decrease in oxygen causes a capillaries to open and arterial resistance to decrease; increased blood flow and increased capillary surface area and decreased diffusion distance increase the supply of oxygen
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How does autoregulation work?
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change in (increase) blood pressure without change in metabolic rate. (increased) oxygen and (decreased) metabolic waste concentration signal to decrease vasodilators and increase vasoconstriction and increase vascular resistance (to stop increased blood flow)
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Is coronary resistance low in systole or diastole and what is the significance of that?
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during exercise diastole is significantly reduced so the heart has less than normal time to deliver blood
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Where are intrinsic mechanisms dominant?
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critical tissues - coronary circulation, brain, working skeletal muscles
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How do extrinsic control mechanisms work?
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nerves and hormones
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Where is acetylcholine released?
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preganglionic synapses and parasympathetic postsynapses
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Where is norepeinephrine released?
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postganglionic sympathetic synpases
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What are the 2 main types of cholinergic receptors?
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muscarinic and nicotinic
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What drugs block muscarininc receptors?
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atropine
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what drugs block nicotinic receptors?
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curare
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What are the 2 main types of androgenic receptors?
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alpha, beta
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what do alpha 1 androgenic receptors do? and what is the activator?
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vasoconstriction of arterioles and norepinephrine/epinephrine
(decrease blood flow to oragnas, increase TPR) |
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what do alpha 2 androgenic receptors do? and what is the activator?
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venoconstriction of veins, and norepinephrine, epinephrine (displaces venous blood to the heart)
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what do beta 1 androgenic receptors do?
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innervate SA node - increase pacemaker rate (norepinephrine and epinephrine) increase HR, SV, and CO
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what do beta 2 androgenic receptors do?
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vasodilation of coronary and skeletal arterioles, epinephrine and norepinephrine
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what do M2 receptors do?
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decrease pacemaker activity; decrease HR, CO (acetylcholine) also at ventricular cells: inhibit norepinephrine and epinephrine release
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what do M3 receptors do?
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via nitric oxide:
coronary arterioles: vasodilation, increase coronary blood flow genitals: vasodilation, erection skeletal muscle: vasodilation, increased muscle blood flow other organs: vasodilation |
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What is the vasoconstriction center?
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continuous sympathetic tone "vasomotor tone," nerves always active
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what is the action of the vasodilator center?
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nerves send inhibitory impulses to vasoconstrictor center; net sympathetic tone is balance between dilator and constriction
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what is the cardiac center?
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excitatory area: sympathetic innervation control of the heart
inhibitory area: parasympathetic innervation to the heart |
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What happens when baroreceptor activity is altered?
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blood pressure is altered so baroreceptor activity changes, CNS alters sympathetic/parasympathetic activity and affecting arteriolar smooth muscle, myocardium, and SA node. Changes to the HR, vasoconstriction, contracility (duration of systole). TPR is changed and so is CO
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Is baroreceptor reflex used in the long term control of BP?
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no, just moment to moment
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What happens to baroreceptors if there is a prolonged increased in BP? (weeks - months)
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"zero out" - becomes the new normals
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what does baroreceptor reflex regulate?
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arterial blood pressure through distention of bv's
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what does the atrial volume receptor reflex regulate?
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atrial volume! through stretch in the atrial walls
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Describe the mechanism for altering a decreaed volume in the atria?
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decreased volume, decreased receptor activity: decreased BP. CNS increases sympathetic activity and decreases parasympathetic activity, kidneys increase renin release which decreases the loss of Na and Cl excretion, pituitary gland increases ADH release which decreases urine flow. hypothalamus increases thirst to increase water intake
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where is renin produced?
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kidney
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what cells in the kidneys are stimulated to secrete renin?
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juxtaglomerular cells within the afferent arteries
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what does renin do?
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converts angiotensinogen to angiotensin 1
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what does angiotensin 1 do
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it is converted to angiotensin 2 in the lungs and increases the production of aldosterone from the adrenal gland
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what does aldosterone do?
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decreases the amount of Na and water excreted
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What are the rapid response control mechanisms?
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CNS ischemic response, baroreceptors, chemoreceptors
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how quickly do rapid response control mechanisms respond?
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immediately
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how quickly do intermediate control mechansims respond?
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minutes to hours
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what are the intermediate control mechanisms?
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stress relaxation, fluid shift, thirst response, ADH
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what is the CNS ischemic response?
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direct stimualation of the vasoconstrictor center in the CNS activating sympathetic response increasing HR and contractility, and increasing vasoconstriction and venoconstriction
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what is the stress-relaxation mechanism?
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drop in blood volume causes vasoconstriction
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what is the capillary fluid shift?
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extracellular fluid moves into blood stream because of altered starlings forces
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what are long term control mechanisms?
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renin-angiotensin system
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