AP in SA node and ventricular myocyte

Question 1

What is Phase 4 in SA node?

Answer 1

Depolarisation

Question 2

What is Phase 0 in SA node?

Answer 2

Upstroke

Question 3

What is Phase 3 in SA node?

Answer 3

Repolarisation

Question 4

What is Phase 4 in VC’s?

Answer 4

Resting phase

Question 5

What is Phase 0 in VC’s?

Answer 5

Upstroke

Question 6

What is Phase 1 in VC’s?

Answer 6

Early repolarisation

Question 7

What is Phase 2 in VC’s?

Answer 7

Plateau phase

Question 8

What is Phase 3 in VC’s?

Answer 8

Late repolarisation

Question 9

What does Depolarisation in Phase 4 in SA node entail?

Answer 9

resting membrane potential, unstable due to slow Na+ influx
TTCC = influx of Ca2+
threshold is reached at -40-50 mV

Question 10

what does upstroke in SA node entail?

Answer 10

LTCC = Ca2+ influx

Question 11

what does phase 3 repolarisation of SA node entail?

Answer 11

slow efflux of K+

Question 12

what does resting phase in VC’s entail?

Answer 12

resting membrane potential = -90mV
K+ fluxes

Question 13

what does early repolarisation inn VC’s entail?

Answer 13

fast Na+ channels close, Na+ influx stops, small K+ efflux

Question 14

what does upstroke in VC’s entail?

Answer 14

fast depolarisation, fast Na+ channels = influx of Na+, threshold is at -65mV

Question 15

what does late repolarisation in VC’s entail?

Answer 15

inactivation of Ca2+ channels, activation of K+ efflux, fast repolarisation