cardiac myocyte contractility

Question 1

where is calcium stored

Answer 1

sarcoplasmic reticulum

Question 2

effect of parasympathetic innervation

Answer 2

decraeses releases of calcium and so decreases contractility

Question 3

effect of sympathetic

Answer 3

increases release of calcium and so increases contractility

Question 4

digoxin

Answer 4

Na+/k/atpase

Question 5

effect of digoxin

Answer 5

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

Question 6

effect of less calcium pumped out

Answer 6

builds up intracellularly, and so inotropy increases

Question 7

what is digoxin used for

Answer 7

congestice cardiac failure where ventricles cant contract well enoguh

Question 8

how does sympathetic stimulation increase cardiac contractility

Answer 8

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

Question 9

what does norepinephrine bind to

Answer 9

b1 receptors on cardia myocytes

Question 10

how does the parasympathetic decrease contractility

Answer 10

by releasing ach which bind to m2 muscarinic receptors

Question 11

positive v negative inotropy

Answer 11

parasympathetic is negative and sympathetic is posiitve

Question 12

junction sin heart

Answer 12

gap junctions

Question 13

potassium on membrane potenitla

Answer 13

-90

Question 14

sodium on membrane potential

Answer 14

+60

Question 15

resting membrane potentila

Answer 15

-70

Question 16

cardiac myocyte resting memrbane potential

Answer 16

-90

Question 17

phase 0 cardiac myocytes

Answer 17

rapid depolarisation due to na+ channels opening

Question 18

phase 1

Answer 18

k+ slowly effluxing, na+ stops - replarisation begins

Question 19

phase 2

Answer 19

ca+ influx balances k+ efflux so plateau

Question 20

phase 3

Answer 20

ca+ stops
k+ efflux continues - repolarisation continues

Question 21

phase 4

Answer 21

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

Question 22

phases of pacemaker cells

Answer 22

phase 4,0,3

Question 23

what does sodium enter through in pacemaker cells

Answer 23

hcn channels

Question 24

phase 4 of cardiac pacemaker cells

Answer 24

sodium influx through funny currents stabilising the resting memrbane potential

Question 25

phade 0 of pacemaker cells

Answer 25

ca+ influx causing rapid depolarisation

Question 26

phase 3 pacemaker cells

Answer 26

k+ efflux cuaisng repolarisation