Term
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Definition
| single contraction of heart |
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Term
| first the ___ contract then the___ |
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Definition
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Term
| The 2 types of cardiac muscles cells are |
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Definition
cells that form a conducting system
contractile cells |
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Term
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Definition
| a system of specialized cardiac muscle cells that initate and distrubute electrical impulses that stimulate contraction. |
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Term
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Definition
| propel contractions that propel blood |
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Term
| automaticity (autorhythmicity) def |
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Definition
| property of cardiac muscle tissue that causes them to contract automatically without neural or hormonal stimulation. |
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Term
| components of conducting system, |
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Definition
Sinoatrial node (SA)
Atrioventriuclar node (AV)
R & L bundle branches
Purkinje fibers
conducting cells |
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Term
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Definition
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Term
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Definition
| btwn atria and ventricles |
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Term
| R & L bundle branches located |
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Definition
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Term
| conducting cells location |
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Definition
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Term
| what is the fcn of the conducting cells |
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Definition
interconnect SA & AV node
distrubute stimulus throughout myocardium |
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Term
| conducting cells distribute electrical stimulus in atria through |
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Definition
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Term
| conducting cells distribute electrical stimulus in ventricle through |
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Definition
AV bundle (aka bundle of His)
& bundle branches |
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Term
| What is an electrocardiogram? |
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Definition
| record of the electrical events in the cardiac cycle |
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Term
| abbrevations for electrocardigram |
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Definition
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Term
| What is a unique feature of the cells of the SA & AV node?, |
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Definition
| they cannot maintain a stable resting potential and have what is called a pre-potential or pacemaker potential. |
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Term
| pre-potential/ pacemaker potential def |
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Definition
no stable resting potential
after each repolarization the membrane gradually drifts toward threshold
aka this is a gradual depolarization |
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Term
| Which node establishes the heart rate? |
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Definition
SA node because it depolarizes first due to the fact its rate of spontaneous depolarization is the fastest
the SA node is able to generate action potentials at a rate of,80-100 per minute |
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Term
| The sinoatrial node contains what type of cells & fcn |
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Definition
pacemaker, spontaneously depolarize
the SA node is connected to the AV node by,internodal pathways. |
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Term
| Activation of the AV node leads to |
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Definition
|
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Term
| what slows the heart rate?, |
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Definition
| parasympathetic nervous system |
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Term
| AV node generates action potentials at what rate?, |
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Definition
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Term
| What would occur if any of the atrial pathways or the SA node becomes damaged?, |
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Definition
the heart beat would depend on AV node at a rate of 40-60 beats per minute
or if cells in the Purkinje fibers begin to depolarize spontaneously it will be at a rate of 20-40 beats per min. |
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Term
| True or false: in the state of disease cells in AV bundle/bundle branches/Purkinje fibers can depolarize spontaneously although blood is still not being pumped efficently., |
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Definition
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Term
| give sequence of electrical excitation throughout the heart, |
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Definition
SA node
AV node
AV bundle
bundle branches
Purkinje fibers |
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Term
| bradycardia, tachycardia def |
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Definition
|
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Term
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Definition
| contains abnormal cells that generate high rate of action potentials that bypass conducting system and disrupt ventricular contractions |
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Term
| the contractile cells recieve their impulse from |
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Definition
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Term
| the resting potential for a ventricular cell is |
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Definition
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Term
| the resting potential for a atrial cell is about |
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Definition
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Term
| t or f: both cardiac and skeletal muscle undergo rapid depolarization?, |
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Definition
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Term
| t or f: both cardiac and skeletal muscle have a plateau phase |
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Definition
no,
in skeletal muscle rapid depolarization is quickly followed by rapid replorization
in cardiac muscle there is an extended period in which CA2+ enters til potential remains near 0mV for an extended period. |
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Term
| t or f: both cardiac and skeletal muscle undergo repolarization |
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Definition
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Term
| give 3 stages of action potential in cardiac muscle cells: |
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Definition
rapid depolarization
the plateau
repolarization |
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Term
rapid depolarization
caused by:
ends with: |
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Definition
Na+ entry
closure of voltage gated sodium channels |
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Term
the plateau
caused by:
ends with: |
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Definition
CA+ entry
closure of slow calicum channels |
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Term
repolarization
caused by:
ends by: |
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Definition
K+ loss
closure of slow potassium channels |
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Term
| define refractory period (in general): |
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Definition
as with any muscle contraction:
for a time after the action potential has occured the membrane will not be able to respond normally to a second stimulus |
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Term
| the refractory occurs in what phase? |
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Definition
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Term
| absolute refractory period def |
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Definition
long
membrane cannot respond at all
b/c Na+ channel are:
open or closed or inactivated |
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Term
| relative refractory period def |
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Definition
shorter,
membrane can only respond to a stronger stimulus
b/c they are less channels available to iniate a response
or Na+ channels are closed but can open
aka membrane is hyperpolarized |
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Term
| order of refractory periods |
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Definition
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Term
| the time btwn depolarization & repolarization is ___ in cardiac muslce than in skeletal muscle |
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Definition
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Term
| why do cardiac cells have a long refractory period?, |
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Definition
prevents: summation
tetanic muscle contractions |
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Term
| what are tetanic muscle contractions?, |
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Definition
| high frequency stimulations leading to a constant contractile state |
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Term
| when does refractory period end?, |
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Definition
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Term
| how does Ca2+ relate to muscle contractions? |
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Definition
| action potential = contraction in cardiac muscle plasma membrane due to an increase Ca2+ around myofibrils |
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Term
| where does the Ca2+ come from to produce muscle contractions? |
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Definition
20% of Ca2+ is outside cell and enters pm of muscle cell during plateau phase
the presence of extracelluar Ca2+ causes the release of addn ca2+ from reserves in sacroplasmic reticulum |
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Term
| what does a beta blocker do? |
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Definition
| prevents Ca2+ from entering cell with intention of producing less contraction to reduce blood pressure. |
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Term
| what happens if you stimulate a Beta 1 receptor?, |
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Definition
increases ca2+ conc which causes more contractions and increases blood pressure
As calcium channels close where does ca2+ go,absorbed by sarcoplasm reticulum |
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Term
| aerobic energy for heart comes from? |
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Definition
fatty acids
glucose
O2 from hemoglobin
myogloblin |
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Term
| the cardiac cycle is the period btwn |
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Definition
start of 1 heartbeat to the beginning of the next
includes contraction & relaxation |
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Term
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Definition
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Term
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Definition
| diastole (pressure falls) |
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