00:01
Action potentials are propagated from the surface to the interior of a muscle fibre by a, the sarcomere, b, the sarcomasmic reticulum, c, the endometeum, or d, the t -tubules.
00:15
So if you have a muscle cell, you have these contractile units, and these are called the sarcomeres, the contractile units.
00:30
And you need the action potential to go from the outside.
00:34
In because you can't just, you can't have only the outer sarcomeres contracting.
00:41
You need all of them to contract, ideally at the same time.
00:44
How does it get there? well, it's not the contractile units, the sarcomere.
00:49
A sarcomere is, it's that thing made up of actin of myosin.
00:54
It's what actually contracts.
00:56
So that's not carrying the action potential.
00:59
It's not the psychoplasmic reticulum.
01:02
The psychoplasmic reticulum, this is what holds the calcium ions and releases them when the action potential hits...