Electrical conduction pathway

Question 1

What is conduction total time?

Answer 1

220 ms

Question 2

Define conduction velocity? Fastest? Slowest?

Answer 2

Speed of depolarisation through tissue
Fastest- Purkinje fibres 2-4 m/s
Allow strong ejection
Slowest- AVN 0.1-0.5 m/s
Allow adequate ventricular filling

Question 3

What is conduction velocity dependent on?

Answer 3

Ion movement- in/out
Interconnectedness- number gap junctions

Question 4

Define term refractory periods?

Answer 4

Time in which myocardial calls can’t depolarise

Question 5

What are the three types of refractory periods?

Answer 5

Absolute- no stimulus generate AP
Effective- large stimulus can generate AP but
too weak to conduct
Relative- large stimulus generate AP and can
conduct

Question 6

Define term excitability?

Answer 6

Excitability- ability myocardial cells to depolarise response to incoming depolarising current

Question 7

What is conduction pathway of heart?

Answer 7

Question 8

Label?

Question 9

What is conduction pathway of heart?

Answer 9

Question 10

What are ECG time intervals?
P, PR, QRS, ST, QT, T

Answer 10

P: 80ms
PR: 120-200ms
QRS and ST: 80-120ms
QT: <420ms
T: 160ms

Question 11

Answer 11