Phys 04 Electrophysiology Of The Heart

Front 1

2 types of heart cells

Back 1

conducting and contractile cells

Front 2

Why is there a delay between atrial and ventricular contraction? What is the purpose of this delay?

Back 2

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.

Front 3

automaticity, def

Back 3

abilty of the SA node to generate its own action potential

Front 4

rhythmicity of the SA node, def

Back 4

ability of SA node to generate action potentials in a regular repetitive matter

Front 5

overdrive suppression, def

Back 5

normal SA node preempts and suppresses all other conducting myocytes from firing

Front 6

characteristiscs of the SA node (3)

Back 6

automaticity, rhythmicity, overdrive suppression

Front 7

name of pathway from SA node to atrial cells (and aka)

Back 7

internodal pathways and interatrial tracts (aka Bachmann's bundle)

Front 8

Trace the normal path of a heart contraction

Back 8

IMAGE

Front 9

Why is conduction significantly slower in the SA node than the AV node?

Back 9

SA cells are smaller, so have more resistance

Front 10

Rate the following in terms of conduction speed: SA node, atrial pathway, AV node, Purkinje fibers, ventricular cardiomyocytes

Back 10

Purkinje fibers (fast) > atrial pathway and ventricular cardiomyocytes > SA node and AV node

Front 11

term for hear functioning as if it is one large cell

Back 11

functional syncytium

Front 12

How is Katp channel activated?

Back 12

Opens when ATP levels drop

Front 13

What is the name of the refractory period during which the cell does not respond to stimulation?

Back 13

effective refractory period

Front 14

What is the name of the refractory period during which a small action potential is possible?

Back 14

relative refractory period

Front 15

Calcium channels open at what membrane potential?

Back 15

at -50mV

Front 16

What kind of channel is lacking in the SA and AV node?

Back 16

voltage-gated Na for fast response, therefore upstroke in SA and AV nodes is slower

Front 17

HCN channel, acronym

Back 17

Hyperpolarization-activated Cyclic nucleiotide gated cation channel (conducts mostly sodium, some potassium)

Front 18

Describe the steps and ionic basis of the slow response action potential (in SA and AV nodal cells) (3)

Back 18

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.

Front 19

HCN channel is activated at what membrane potential?

Back 19

at -65mV

Front 20

Summarize the effect of the ANS on cardiac tissues

Back 20

[PHYS 04. Effect of ANS activation on different cardiac tissues]

Front 21

in what two ways does protein kinase A contribute to the lusitropic effect?

Back 21

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.

Front 22

Which two receptors affect adenylyl cyclase? Which one is parasympathetic, sympathetic?

Back 22

Vagus > M2 receptor > inhibitory. Sympathetic > β1 receptor > excitatory

Front 23

What happens to the α and βγ subunits of a muscarinic 2 receptor after ACh binds?

Back 23

α binds to K+ channels and opens them, while βγ binds directly to adenyl cyclase inhibits it, reducing the level of cAMP.

Front 24

What happens when ACh binds to a M2 receptor in the heart? (detailed flashcard)

Back 24

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.

Front 25

describe the steps of β1 receptor activation, specifically in the SA and AV nodal cells (8) (detailed flashcard)

Back 25

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

Front 26

lusitropic, def

Back 26

relaxing effect ("loosey goosey")

Front 27

effect of norepinephrine on the heart

Back 27

increases generation of cAMP through β adrenergic receptors > activates PKA > PKA phosphorylates L-type channels > increased influx of Ca > increased contractile force

Front 28

What event occurs during the P-wave?

Back 28

atrial depolarization

Front 29

What is the cause of atrial fibrilation?

Back 29

abnormal electrical pathways

Front 30

What does the PR interval represent? Normal length of time?

Back 30

time from SA node activation to AV node activation; usually >0.2 seconds

Front 31

2 types of heart cells

Back 31

conducting and contractile cells

Front 32

Why is there a delay between atrial and ventricular contraction? What is the purpose of this delay?

Back 32

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.

Front 33

automaticity, def

Back 33

abilty of the SA node to generate its own action potential

Front 34

rhythmicity of the SA node, def

Back 34

ability of SA node to generate action potentials in a regular repetitive matter

Front 35

overdrive suppression, def

Back 35

normal SA node preempts and suppresses all other conducting myocytes from firing

Front 36

characteristiscs of the SA node (3)

Back 36

automaticity, rhythmicity, overdrive suppression

Front 37

name of pathway from SA node to atrial cells (and aka)

Back 37

internodal pathways and interatrial tracts (aka Bachmann's bundle)

Front 38

Trace the normal path of a heart contraction

Back 38

IMAGE

Front 39

Why is conduction significantly slower in the SA node than the AV node?

Back 39

SA cells are smaller, so have more resistance

Front 40

Rate the following in terms of conduction speed: SA node, atrial pathway, AV node, Purkinje fibers, ventricular cardiomyocytes

Back 40

Purkinje fibers (fast) > atrial pathway and ventricular cardiomyocytes > SA node and AV node

Front 41

term for hear functioning as if it is one large cell

Back 41

functional syncytium

Front 42

How is Katp channel activated?

Back 42

Opens when ATP levels drop

Front 43

What is the name of the refractory period during which the cell does not respond to stimulation?

Back 43

effective refractory period

Front 44

What is the name of the refractory period during which a small action potential is possible?

Back 44

relative refractory period

Front 45

Calcium channels open at what membrane potential?

Back 45

at -50mV

Front 46

What kind of channel is lacking in the SA and AV node?

Back 46

voltage-gated Na for fast response, therefore upstroke in SA and AV nodes is slower

Front 47

HCN channel, acronym

Back 47

Hyperpolarization-activated Cyclic nucleiotide gated cation channel (conducts mostly sodium, some potassium)

Front 48

Describe the steps and ionic basis of the slow response action potential (in SA and AV nodal cells) (3)

Back 48

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.

Front 49

HCN channel is activated at what membrane potential?

Back 49

at -65mV

Front 50

Summarize the effect of the ANS on cardiac tissues

Back 50

[PHYS 04. Effect of ANS activation on different cardiac tissues]

Front 51

in what two ways does protein kinase A contribute to the lusitropic effect?

Back 51

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.

Front 52

Which two receptors affect adenylyl cyclase? Which one is parasympathetic, sympathetic?

Back 52

Vagus > M2 receptor > inhibitory. Sympathetic > β1 receptor > excitatory

Front 53

What happens to the α and βγ subunits of a muscarinic 2 receptor after ACh binds?

Back 53

α binds to K+ channels and opens them, while βγ binds directly to adenyl cyclase inhibits it, reducing the level of cAMP.

Front 54

What happens when ACh binds to a M2 receptor in the heart? (detailed flashcard)

Back 54

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.

Front 55

describe the steps of β1 receptor activation, specifically in the SA and AV nodal cells (8) (detailed flashcard)

Back 55

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

Front 56

lusitropic, def

Back 56

relaxing effect ("loosey goosey")

Front 57

effect of norepinephrine on the heart

Back 57

increases generation of cAMP through β adrenergic receptors > activates PKA > PKA phosphorylates L-type channels > increased influx of Ca > increased contractile force

Front 58

What event occurs during the P-wave?

Back 58

atrial depolarization

Front 59

What is the cause of atrial fibrilation?

Back 59

abnormal electrical pathways

Front 60

What does the PR interval represent? Normal length of time?

Back 60

time from SA node activation to AV node activation; usually >0.2 seconds