Term
| the basic types of activites required by the heart to impart potential and kinetic energy to blood |
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Definition
| excitation, condiction, & contraction |
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Term
| T/F in a normal heart excitation, conduction, & contraction are inseperately linked |
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Definition
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Term
| Heart tissue that express excitability |
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Definition
| atrial m., ventricular m., conductive tissue, and pacemaker cells |
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Term
| specialize in contracting (doing work) |
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Definition
| atrial and ventricular muscle |
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Term
| capable of spontaneous depolarization |
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Definition
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Term
| specialize in propagqating impulses from one area of the heart to another and can also depolarize spontanteously at a slower rate |
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Definition
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Term
| pacemaker, transitional cells, purkinje cells, atrial and ventricular muscle cells are able to work together because... |
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Definition
| they display slightly different physiologic properties that alow them to preform cyclic activities |
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Term
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Definition
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Term
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Definition
| transmit impulses throught the heart |
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Term
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Definition
| the larger the cardiac cell size |
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Definition
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Definition
few myofibrils or mitochondria and a little glycogen
Have no intercalated disks |
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Term
| P cells are the macemakes cells that conduct at a velocity of |
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Definition
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Term
| transmit impulses from P cells to other cells in the heart |
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Definition
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Term
| Containnumerous myofibrils and mitochondria but lack well adaptive T-tubules. 20-30 microns long & make side to side (end to end) contacts via intercalated disks |
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Definition
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Term
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Definition
| have a well developed sarcoplasmice reticulum and t tubles. 100 microns in length. abundant myofibrils and mitochondria. COnduct at a velocity of 1m/sec |
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Term
| Cardiac cells are excited by cells that have |
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Definition
| inherent cyclic discharge rhythems |
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Term
| Cardiac cells form a network called __ because they can receive electrical impulses directly from other cells |
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Definition
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Term
| Cardiac cells have what kind of syncytium? |
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Definition
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Term
| intercalated disks are located at... |
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Definition
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Term
| the functional specializations of intercalated disks |
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Definition
desmosomes
fascia adherens
nexuses |
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Term
| These are sparce in sinoatrial & atrioventricular nodal cells but plentiful in Perkinje cells where conduction is rapid |
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Definition
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Term
| The type of action potential produced in the SAN & the AVN |
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Definition
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Term
| The tyoe of action potential that occurs in the atrial muscle cells, ventricular muscle cells & the purkinje system |
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Definition
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Term
| Functions as the pacemaker of the heart by virtue of its high rate of spontaneous depolarization |
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Definition
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Term
| Spontaneous discharges of the pacemaker does not alter what in other cells? |
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Definition
| inherent rate of discharge |
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Term
| Transmembrane poteneials (TMP) of SAN have no __ but do have ___ |
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Definition
| stable resting membrane potential; MRP |
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Term
| Maximum repolarization potential (MRP) |
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Definition
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Term
| When __ is reached, the cells begin to hypopolarize & will eventually give rise to anothr action potential |
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Definition
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Term
| ___ has a long refractory periods which prevent the ventricles from being restimulated prematurely |
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Definition
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Term
| The AV nodes properties are helpful in cases of.. |
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Definition
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Term
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Definition
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Term
| AV node provides pacing at about __ of the SAN |
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Definition
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Term
| The __ of the spontaneous change during pacemaer potential is one of the determinates of heart rate. |
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Definition
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Term
| The slow decrease in TMP is brought about by ___ |
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Definition
| a decline in the outward potassium current |
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Term
| __ increases towards the end of the pacemaker potential |
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Definition
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Term
| What increases during the rising phase of the action potential? |
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Definition
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Term
| There is an absence of fast __ channels but a presence of __ __ chennels. |
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Definition
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Term
| T/F The rising phase is caused promarily by calcium? |
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Definition
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Term
| Increases potassium and thus will slow the heart rate |
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Definition
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Term
| increases intracellules concentrations of calcium and sodium thus increasing the heart rate |
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Definition
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Term
| The resting potential of fast action potentials is much more __ than slow action potentials |
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Definition
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Term
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Definition
| rapid initial depolarization characterized by a reversal potential |
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Term
| The reversal potential is almost soel caused by |
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Definition
| sodium influx through voltage-gated fast sodium channels |
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Term
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Definition
| initial rapid repolarization that begins to return the potential towards zero |
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Term
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Definition
| rapid decrease in conductance of the membrane to sodium and increase towards potassium |
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Term
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Definition
| slow phase of repolarzation resulting in a plateau caused by slow influx of calcium and sodium |
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Term
| During the Phase 2 plateau, the cell membrane is more permeable to __ |
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Definition
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Term
| Because of the Phase 2 shorter plateau, what can beat faster than the ventricles |
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Definition
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Term
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Definition
| a final rapid repolarization which returns the membrane to its resting potential |
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Term
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Definition
| decrease influx of calcuim and an increase in outward flow of potassium |
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Term
| During what phase is calcium pumped back into the sarcoplasmic retculum or out into the extracellular fluid? |
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Definition
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Term
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Definition
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Term
| During what phase is the excess sodium pumped out of the cell? |
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Definition
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Term
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Definition
| atrial & ventricular muscle cells & Purkinje fibers |
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Term
| __ eliminates the fast responses of muscle cells and Purkinje fibers and converts them to the slow type of action potential |
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Definition
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Term
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Definition
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Term
| ___ are calcuim antagonists and partially block the slow enterance of calcium. Can stabelize the heart in cases of arrythmias |
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Definition
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Term
| True or False: The calcium that influxes during the AP is enough for contraction |
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Definition
| False; some must be brought in fromt he S.R. |
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Term
| Ways the rate of discharge in a pacemaker cells can change |
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Definition
slope of diastic depolarization
threshold potential
resting potential |
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Term
| tachycardia is a possibe effect of__ |
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Definition
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Term
| Stimulating __ will result in bradycardia, a negative chronotropic response. |
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Definition
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Term
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Definition
| negative chronotropic effect |
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Term
Which statent about the features of cardiac cells is false?
A. the full polarity of the resting potential is not as great as other cells
B. The oversoot of the action potential is more
C. The time course of the action potential is slower |
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Definition
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Term
| The transmission velocity in the atrial muscle, bundle of His & ventricular muscle is about... |
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Definition
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Term
| Conduction velocity in the AV node is about (not in the Perkinje systern)... |
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Definition
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Term
| In the Purkije systern the AV conduction velocity is about... |
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Definition
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Term
Conducton velocity depends on all of the following except:
A. Fiber diameter
B. Rapidity of depolarization
C. Rapidity of repolarization
D. Amplitude of the action potential |
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Definition
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Term
| There is no wave for __ in the ECG due to this being simultaneous with another depolarization |
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Definition
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Term
| cardiac muscle is different than skeletal muscle physiologically because.... |
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Definition
| cardiac action potentials are longer |
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Term
| The peak force of the muscle twitch in cardiac muscle is reached simultaneous with... |
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Definition
| the AP is reaching the end of repolarization |
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Term
| What, in cardiac muscle, not only initiates but modulates a mechanical event? |
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Definition
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Term
| Because electrical & mechanical events are very near the same duration in cardiac cells, cardiac muscles cannot __ |
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Definition
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Term
| ___ strengthens the contractile process in the heart by interfering with the sodium-potasium movement in the cell-membrane |
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Definition
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Term
| Tension and length are very hard to measure in cardiac muscle, so they may be replaced with |
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Definition
| cardiac output & end-diastolic volume |
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Term
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Definition
| the ability of the heart to self-regulate in response to changing loads of inflowing blood |
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Term
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Definition
| any agent which alters the force of contraction without changing the degree of strech on cardiac fibers |
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Term
| __ regulation occurs when filling of the heart increases cardiac metabolism & hence the force of contraction |
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Definition
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Term
| __ regulation areises from a changing fiber length |
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Definition
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Term
| True/False The heteromteric means expresses the Frank-Starling Law |
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Definition
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Term
| __ of the energy requiremements of the heart are derived from non-esterfied fatty acids & the remainder by glucose |
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Definition
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Term
| The heart does not need neural input to finction, but it is innervated by nerve terminals of the __ |
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Definition
| ANS (both sympathetic and parasympathetic) |
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Term
These nerve terminals of the ANS contain:
A. granular vesicles = adrenergic
B. agranular vesicles = cholinergic |
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Definition
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Term
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Definition
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Term
__ innervation to hte heart increases te rate & force of contraction
A. sympathetic
B. parasympathetic |
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Definition
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Term
| The phenomenon caused by isoproterenol may be regulated by __ |
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Definition
| increased intracellular levels of cyclic AMP, the second messenger for many beta actions |
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Term
| The parasympathetic activities of the heart are directed promarily towards __ |
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Definition
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Term
| The parasympathetic system has very little effect on cardiac __ |
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Definition
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Term
| Acetylcholine decreases the slow inward current due to calcium influx but more importantly, increased __, thus decreasing the effects of vagal stimulation. |
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Definition
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Term
increased extra cellular potassium limits he efffect of __ on __ muscles
A. Ach, atrial
B. APM; Purkinje
C. Ach; Purkinje
D. Ach; Ventricular |
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Definition
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