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60 Cards in this Set
- Front
- Back
2 types of heart cells
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conducting and contractile cells
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Why is there a delay between atrial and ventricular contraction? What is the purpose of this delay?
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annulus fibrosis prevents electrical impulse from passing into the ventricle, so the impulse must first go to the AV node. Delay permits atrial contraction before ventricular contraction.
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automaticity, def
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abilty of the SA node to generate its own action potential
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rhythmicity of the SA node, def
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ability of SA node to generate action potentials in a regular repetitive matter
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overdrive suppression, def
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normal SA node preempts and suppresses all other conducting myocytes from firing
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characteristiscs of the SA node (3)
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automaticity, rhythmicity, overdrive suppression
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name of pathway from SA node to atrial cells (and aka)
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internodal pathways and interatrial tracts (aka Bachmann's bundle)
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Trace the normal path of a heart contraction
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IMAGE
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Why is conduction significantly slower in the SA node than the AV node?
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SA cells are smaller, so have more resistance
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Rate the following in terms of conduction speed: SA node, atrial pathway, AV node, Purkinje fibers, ventricular cardiomyocytes
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Purkinje fibers (fast) > atrial pathway and ventricular cardiomyocytes > SA node and AV node
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term for hear functioning as if it is one large cell
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functional syncytium
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How is Katp channel activated?
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Opens when ATP levels drop
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What is the name of the refractory period during which the cell does not respond to stimulation?
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effective refractory period
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What is the name of the refractory period during which a small action potential is possible?
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relative refractory period
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Calcium channels open at what membrane potential?
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at -50mV
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What kind of channel is lacking in the SA and AV node?
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voltage-gated Na for fast response, therefore upstroke in SA and AV nodes is slower
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HCN channel, acronym
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Hyperpolarization-activated Cyclic nucleiotide gated cation channel (conducts mostly sodium, some potassium)
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Describe the steps and ionic basis of the slow response action potential (in SA and AV nodal cells) (3)
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1 Na enters through HCN (funny current), voltage-gated Ca channel opens, 2 K+ current decreases due to K+ channel inactivation. Combined effect of steps 1 and 2 is gradual membrane depolarization. 3 when membrane potential passes -50mV, L-type channels open.
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HCN channel is activated at what membrane potential?
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at -65mV
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Summarize the effect of the ANS on cardiac tissues
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[PHYS 04. Effect of ANS activation on different cardiac tissues]
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in what two ways does protein kinase A contribute to the lusitropic effect?
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lusitropic effect of catecholamines: 1 PKA phosphorylates phospholamban so that it cannot inhibit SERCA, which allows SERCA to more rapidly remove Ca from intracellular space. 2 phosphorylates Troponin I, destabilizing actin-myosin cross-bridges.
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Which two receptors affect adenylyl cyclase? Which one is parasympathetic, sympathetic?
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Vagus > M2 receptor > inhibitory. Sympathetic > β1 receptor > excitatory
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What happens to the α and βγ subunits of a muscarinic 2 receptor after ACh binds?
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α binds to K+ channels and opens them, while βγ binds directly to adenyl cyclase inhibits it, reducing the level of cAMP.
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What happens when ACh binds to a M2 receptor in the heart? (detailed flashcard)
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βγ SUBUNIT: activates G-protein activated inwardly rectifying K+ channel (GIRK), increases K+ currents, results in slower, less forceful beats (IMAGE). α SUBUNIT: binds to and inhibits adenyl cyclase/cAMP, which decreases Na influx through HCN channels and decreases Ca efflux through voltage-gated Ca channels.
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describe the steps of β1 receptor activation, specifically in the SA and AV nodal cells (8) (detailed flashcard)
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1 norepinephrine binds to β1 receptor, 2 G-protein releases GDP and binds GTP, α-subunit dissociates, 3 α-subunit binds to and ACTIVATES adenylyl cyclase, 4 cAMP levels INCREASE, 5 cAMP activates protein kinases, 6 protein kinases phosphorylate HCN and voltage-gated Ca channels, 7 increases Na influx through HCN channels, and 8 increases Ca influx through voltage-gated Ca channels
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lusitropic, def
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relaxing effect ("loosey goosey")
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effect of norepinephrine on the heart
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increases generation of cAMP through β adrenergic receptors > activates PKA > PKA phosphorylates L-type channels > increased influx of Ca > increased contractile force
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What event occurs during the P-wave?
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atrial depolarization
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What is the cause of atrial fibrilation?
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abnormal electrical pathways
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What does the PR interval represent? Normal length of time?
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time from SA node activation to AV node activation; usually >0.2 seconds
|
|
2 types of heart cells
|
conducting and contractile cells
|
|
Why is there a delay between atrial and ventricular contraction? What is the purpose of this delay?
|
annulus fibrosis prevents electrical impulse from passing into the ventricle, so the impulse must first go to the AV node. Delay permits atrial contraction before ventricular contraction.
|
|
automaticity, def
|
abilty of the SA node to generate its own action potential
|
|
rhythmicity of the SA node, def
|
ability of SA node to generate action potentials in a regular repetitive matter
|
|
overdrive suppression, def
|
normal SA node preempts and suppresses all other conducting myocytes from firing
|
|
characteristiscs of the SA node (3)
|
automaticity, rhythmicity, overdrive suppression
|
|
name of pathway from SA node to atrial cells (and aka)
|
internodal pathways and interatrial tracts (aka Bachmann's bundle)
|
|
Trace the normal path of a heart contraction
|
IMAGE
|
|
Why is conduction significantly slower in the SA node than the AV node?
|
SA cells are smaller, so have more resistance
|
|
Rate the following in terms of conduction speed: SA node, atrial pathway, AV node, Purkinje fibers, ventricular cardiomyocytes
|
Purkinje fibers (fast) > atrial pathway and ventricular cardiomyocytes > SA node and AV node
|
|
term for hear functioning as if it is one large cell
|
functional syncytium
|
|
How is Katp channel activated?
|
Opens when ATP levels drop
|
|
What is the name of the refractory period during which the cell does not respond to stimulation?
|
effective refractory period
|
|
What is the name of the refractory period during which a small action potential is possible?
|
relative refractory period
|
|
Calcium channels open at what membrane potential?
|
at -50mV
|
|
What kind of channel is lacking in the SA and AV node?
|
voltage-gated Na for fast response, therefore upstroke in SA and AV nodes is slower
|
|
HCN channel, acronym
|
Hyperpolarization-activated Cyclic nucleiotide gated cation channel (conducts mostly sodium, some potassium)
|
|
Describe the steps and ionic basis of the slow response action potential (in SA and AV nodal cells) (3)
|
1 Na enters through HCN (funny current), voltage-gated Ca channel opens, 2 K+ current decreases due to K+ channel inactivation. Combined effect of steps 1 and 2 is gradual membrane depolarization. 3 when membrane potential passes -50mV, L-type channels open.
|
|
HCN channel is activated at what membrane potential?
|
at -65mV
|
|
Summarize the effect of the ANS on cardiac tissues
|
[PHYS 04. Effect of ANS activation on different cardiac tissues]
|
|
in what two ways does protein kinase A contribute to the lusitropic effect?
|
lusitropic effect of catecholamines: 1 PKA phosphorylates phospholamban so that it cannot inhibit SERCA, which allows SERCA to more rapidly remove Ca from intracellular space. 2 phosphorylates Troponin I, destabilizing actin-myosin cross-bridges.
|
|
Which two receptors affect adenylyl cyclase? Which one is parasympathetic, sympathetic?
|
Vagus > M2 receptor > inhibitory. Sympathetic > β1 receptor > excitatory
|
|
What happens to the α and βγ subunits of a muscarinic 2 receptor after ACh binds?
|
α binds to K+ channels and opens them, while βγ binds directly to adenyl cyclase inhibits it, reducing the level of cAMP.
|
|
What happens when ACh binds to a M2 receptor in the heart? (detailed flashcard)
|
βγ SUBUNIT: activates G-protein activated inwardly rectifying K+ channel (GIRK), increases K+ currents, results in slower, less forceful beats (IMAGE). α SUBUNIT: binds to and inhibits adenyl cyclase/cAMP, which decreases Na influx through HCN channels and decreases Ca efflux through voltage-gated Ca channels.
|
|
describe the steps of β1 receptor activation, specifically in the SA and AV nodal cells (8) (detailed flashcard)
|
1 norepinephrine binds to β1 receptor, 2 G-protein releases GDP and binds GTP, α-subunit dissociates, 3 α-subunit binds to and ACTIVATES adenylyl cyclase, 4 cAMP levels INCREASE, 5 cAMP activates protein kinases, 6 protein kinases phosphorylate HCN and voltage-gated Ca channels, 7 increases Na influx through HCN channels, and 8 increases Ca influx through voltage-gated Ca channels
|
|
lusitropic, def
|
relaxing effect ("loosey goosey")
|
|
effect of norepinephrine on the heart
|
increases generation of cAMP through β adrenergic receptors > activates PKA > PKA phosphorylates L-type channels > increased influx of Ca > increased contractile force
|
|
What event occurs during the P-wave?
|
atrial depolarization
|
|
What is the cause of atrial fibrilation?
|
abnormal electrical pathways
|
|
What does the PR interval represent? Normal length of time?
|
time from SA node activation to AV node activation; usually >0.2 seconds
|