Cardiovascular System
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| show | contractile cells, which have similar features to skeletal muscle cells and nodal/conducting cells that have features similar to nerve cells.
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| show | the real muscle cells of the heart and form most of the walls of the atria and ventricles; they have similar features and contract in almost the same way as skeletal muscle fibers
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| how do contractile cells differ from skeletal muscle? | show 🗑
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| what are nodal cells? | show 🗑
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| what does it mean that cardiac muscle is auto-rhythmic? | show 🗑
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| what is the pacemaker of the heart? Why? | show 🗑
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| show | both the parasympathetic and sympathetic nervous systems have input into the SA node to regulate the rate of discharge
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| show | the parasympathetic nervous system decreases the rate of discharge; the sympathetic nervous system increases the rate of discharge
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| show | the membranes of SA nodal cells have a natural “leakiness” to sodium; this slow sodium influx generates the pacemaker potential
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| show | it is higher
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| show | calcium channels open and calcium rushes in quickly, causing depolarization; calcium channels then close, and potassium channels open, causing potassium to rush out, resulting in repolarization
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| what happens after an action potential is generated by the SA node? | show 🗑
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| how frequently does the SA node depolarize? | show 🗑
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| what is the effect of parasympathetic input to the SA node? | show 🗑
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| show | during the fight or flight response, sympathetic stimulation to the SA node increases the rate of depolarization; the sympathetic nervous system also innervates the ventricular musculature extensively; stimulation causes an increase in contractility of th
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| show | cardiac muscle cells are connected by regions of membrane called intercalated discs (very low electrical resistance); an action potential can freely travel from one cell to the next. A mass of cardiac muscle is therefore said to act as a functional syncit
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| what is a functional syncitium? | show 🗑
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| how is the atrial musculature isolated from the ventricular musculature? | show 🗑
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| show | it travels through the atrial musculature (the left atrium receives the impulse via Bachman's bundle) and at the same time, the action potential is conducted down the internodal pathway to the AV node.
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| show | the AV node delays the action potential to allow the atria to depolarize before the impulse travels to the ventricles
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| what is the function of the AV node? | show 🗑
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| where does the impulse travel after the AV node? | show 🗑
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| show | aka AV bundle; it conducts the impulse to the ventricles, through the bundle branches
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| where is the Bundle of His located? What is its structure? | show 🗑
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| where does the impulse travel after the Bundle of His and the bundle branches? | show 🗑
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| what is the function of the purkinje fibers? | show 🗑
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| show | SA node -> Bachman's bundle -> AV node -> Bundle of His -> bundle branches -> Purkinje fibers
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| how does the heart contract? | show 🗑
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| how can the electrical activity of the heart be monitored? | show 🗑
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| what information can an ECG provide? | show 🗑
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| show | no, only electrical activation of the heart muscle; it does not tell you whether or not contraction actually occurred in response to stimulation
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| how do you calculate the heart rate from an ECG by knowing the paper speed? | show 🗑
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| show | 12
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| what do the "waves" on the ECG represent? | show 🗑
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| what is normal sinus rhythm? | show 🗑
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| show | heart rate slower than normal
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| show | heart rate faster than normal
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| show | aka atrioventricular block; lack of synchrony between atrial and ventricular electrical activities (ventricles are driven by a pacemaker cell in the bundle of His)
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| what is ectopic focus? | show 🗑
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| show | an abnormal site in the heart acting as the pacemaker; the ECG tracing generated is abnormal
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| show | (blank)
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| show | uncoordinated electrical activity of the heart; ventricular fibrillation causes the heart to contract like a "bag of worms" in that there is no forceful contraction produced; it is incompatible with life
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| show | study ECG drawings in lab manual!
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| what is the cardiac cycle? | show 🗑
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| what is systole? | show 🗑
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| show | time when ventricles are relaxed
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| what is diastasis? | show 🗑
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| what is atrial systole? | show 🗑
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| what is isovolumetric contraction? | show 🗑
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| show | the volume of blood in the ventricles during isovolumetric contraction; it measures about 120 ml; recorded during isovolumetric contraction
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| what is diastolic blood pressure? | show 🗑
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| what is the period of rapid ejection? | show 🗑
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| show | the top number of blood pressure; normally about 120 mmHg; recorded during the period of rapid ejection
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| show | the ventricles are closed containers again and they are relaxing; they contain the smallest volume of blood at the point; ventricular volume and pressure fall below atrial pressure and the AV valves open
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| what is end systolic volume? | show 🗑
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| show | blood rushes into the ventricles from the atria, vena cavae, and pulmonary veins
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| show | medullary cardiovascular center, afferent nerve, limbic system and other variables
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| show | in the medulla of the brain; it gives off efferent (motor) neurons of both branches of the autonomic nervous system
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| where do the cardiovascular center parasympathetic fibers travel and what is their impact? | show 🗑
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| what is vagal tone? | show 🗑
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| show | incr heart rate & cardiac contractility; norepinhephrine (epinephrine, adrenaline) released to SA node (& AV node) which opens Na+ & Ca++ channels, membrane depolarizes & reaches threshold more rapidly; extra Ca++ incr force of contraction, stroke volume
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| show | it stimulates either vasoconstriction or vasodilation of the peripheral blood vessels.
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| what is the function of the afferent nerves? | show 🗑
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| what occurs in the baroreceptor reflex whe blood pressure increases? | show 🗑
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| what occurs in the baroreceptor reflex when blood pressure decreases? | show 🗑
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| show | plays a role in regulation of heart function, particularly heart rate; the limbic system governs the primitive emotions of rage, fear, aggression, etc. For example, your heart rate increases when you are angry
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| what are the other variables that control heart regulation? | show 🗑
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| show | when body temperature increases, so does the heart rate and vice versa
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| what is the impact of serum K+ on heart rate? | show 🗑
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| what is the impact of epinephrine and thyroxine on heart rate? | show 🗑
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| show | 70 bpm (the heart's intrinsic rate is 100 bpm, but parasympathetic stimulation at rest slows it to 70 bpm)
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| show | incr in EDV -> incr in stroke volume & vice versa; stretching (due to increased volume) causes more Ca++ channels to open -> more Ca++ in muscle cell -> more forcefully it contracts during systole -> more blood ejected -> lower ESV -> higher stroke volume
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| show | aka MAP; pressure of the blood against the walls of the arteries and arterioles
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| show | MAP = cardiac output X resistance to flow
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| show | cardiac output is the amount of blood pumped by the heart in a given time period, usually per minute; cardiac output = heart rate X stroke volume
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| show | at rest, the cardiac output is roughly 5 liters (1.3 gallons) of blood every minute; during vigorous exercise, this can increase up to 20 l/min (5.2 gallons/min) in a normal individual and up to 35 to 40 l/min (10 gallons/min) in a highly trained athlete
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| show | Resistance to flow = fluid friction X vessel length /vessel diameter
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| show | the amount of blood pumped by the heart per beat; stroke volume = end-diastolic volume - end-systolic volume
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| how can MAP be calculated from blood pressure? | show 🗑
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| show | amt of blood returned to heart by the circulation per unit time, usually per minute; normally, cardiac output = venous return; this means the heart is capable of pumping out the amt of blood it receives, which can vary according to posture, activity level
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| what is endothelin? | show 🗑
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| what is NO? | show 🗑
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| What effect does blood volume have on blood pressure? | show 🗑
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| What effect does heart rate have on blood pressure? | show 🗑
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| What effect does stroke volume have on blood pressure? | show 🗑
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| show | direct; increased venous return means that the cardiac output must increase (which can be done by increasing the heart rate and/or the stroke volume) which in turn means that the MAP increases.
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| What effect does strength of myocardial contraction have on blood pressure? | show 🗑
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| What effect does sympathetic stimulation have on blood pressure? | show 🗑
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| What effect does parasympathetic stimulation have on blood pressure? | show 🗑
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| show | increase; increase heart rate and therefore increases cardiac output and MAP
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| show | increase; increase heart rate and therefore increases cardiac output and MAP
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| What effect does vasopressin (aka ADH) have on blood pressure? | show 🗑
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| show | increases; this increases blood volume and increases vasoconstriction and therefore increases MAP.
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| show | increase; increased viscosity causes increased fluid friction. This increases resistance to flow and therefore MAP.
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| What effect does the length of blood vessels have on blood pressure? | show 🗑
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| show | increase; because it is a vasoconstrictor, it increases resistance and increases MAP
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| What effect does NO have on blood pressure? | show 🗑
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| show | decrease; because it inhibits the renin-angiotensin system, it decreases MAP
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| what are the heart sounds heard with a stethoscope? | show 🗑
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| what is "lub"? What is "dup"? | show 🗑
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| what provides resistance to blood flow: | show 🗑
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| show | pressure gradient and diameter
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| show | (blank)
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| show | capillary hydrostatic pressure, interstitial-fluid hydrostatic pressure, osmotic force due to plasma proteins (in the blood), osmotic force due to interstitial fluid protein concentration
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| show | 1) local control mechanisms in the organs themselves 2) humoral mechanisms that rely on chemicals in the blood 3) the ANS which alters cardiac output and blood flow to organs
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| what are 3 vasoconstricting agents? | show 🗑
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| show | epinephrine, kinins, histamine, ANF
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| show | causes overall VASOCONSTRICTION by releasing norepinephrine onto smooth muscle of blood vessels, and releases ACh onto blood vessels in skeletal muscle producing a VASODILATION, redirecting blood away from the digestive system, kidneys, & spleen
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| how does the parasympathetic nervous system impact vessel diameter? | show 🗑
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| show | baroreceptors are sensitive to any stretching of the blood vessel walls; inc in blood pressure stretches walls -> sends an action potential to cardioregulatory & vasomotor centers -> decreases heart rate & contractility, increases blood vessel diameter
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| show | blood pressure = cardiac output X total peripheral resistance
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| show | cardiac output = heart rate X stroke volume
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| what is the equation for flow? | show 🗑
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| what controls heart rate and stroke volume? | show 🗑
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