Details of pacemaker cardiomyocytes

Question 1

unique features of pacemaker cells

Answer 1

1. no sarcomeres
2. few gap junctions
3. very leaky to sodium
4. No true resting phase
5. no VG Na + channels
6. low threshold potential
7. depolarize with calcium

Question 2

why do SA nodes have fewer gap junctions?

Answer 2

the SA node hold onto the action potentials generated for a brief period of time before they are conveyed to other parts of the body

Question 3

what does being naturally leaky to sodium allow?

Answer 3

it allows the pacemaker cells to depolarize quickly essentially beating any other auto rhythmic cells to the punch when it comes to action potential generation

Question 4

funny currents are caused by what

Answer 4

sodium ions leaking in just as soon as repolarization from the last action potential ends

Question 5

funny current

Answer 5

a sodium channel that is not always open but goes from -60 mv to about -50 mv
-are not involved in the depolarization of the SA nodal cells

Question 6

What is the significance of the Bachman’s branch?

Answer 6

the only way we can get an action potential from the SA node from the right atrium to the left atrium if you have scar tissue here or damage to the left atrium doesn’t get any info on when to beat so the WCM of the left atrium will be contracting at a different rate