cardiac myocyte contractility Flashcards

1
Q

where is calcium stored

A

sarcoplasmic reticulum

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2
Q

effect of parasympathetic innervation

A

decraeses releases of calcium and so decreases contractility

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3
Q

effect of sympathetic

A

increases release of calcium and so increases contractility

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4
Q

digoxin

A

Na+/k/atpase

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5
Q

effect of digoxin

A

decreases sodium gradient and so less calcium is able to be pumped as it relies on energy from the sodium pump

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6
Q

effect of less calcium pumped out

A

builds up intracellularly, and so inotropy increases

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7
Q

what is digoxin used for

A

congestice cardiac failure where ventricles cant contract well enoguh

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8
Q

how does sympathetic stimulation increase cardiac contractility

A

by releasing norepinephrine, which bind to beta 1 receptors on cardiomyocytes

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9
Q

what does norepinephrine bind to

A

b1 receptors on cardia myocytes

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10
Q

how does the parasympathetic decrease contractility

A

by releasing ach which bind to m2 muscarinic receptors

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11
Q

positive v negative inotropy

A

parasympathetic is negative and sympathetic is posiitve

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12
Q

junction sin heart

A

gap junctions

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13
Q

potassium on membrane potenitla

A

-90

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14
Q

sodium on membrane potential

A

+60

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15
Q

resting membrane potentila

A

-70

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16
Q

cardiac myocyte resting memrbane potential

A

-90

17
Q

phase 0 cardiac myocytes

A

rapid depolarisation due to na+ channels opening

18
Q

phase 1

A

k+ slowly effluxing, na+ stops - replarisation begins

19
Q

phase 2

A

ca+ influx balances k+ efflux so plateau

20
Q

phase 3

A

ca+ stops
k+ efflux continues - repolarisation continues

21
Q

phase 4

A

k meets equilibrium and so sodium and calcium balance out potassium causing resting membrane potential

22
Q

phases of pacemaker cells

A

phase 4,0,3

23
Q

what does sodium enter through in pacemaker cells

A

hcn channels

24
Q

phase 4 of cardiac pacemaker cells

A

sodium influx through funny currents stabilising the resting memrbane potential

25
Q

phade 0 of pacemaker cells

A

ca+ influx causing rapid depolarisation

26
Q

phase 3 pacemaker cells

A

k+ efflux cuaisng repolarisation