Different is a nice muscle. The impulse tells the cardiac contract doesn’t come from Nwe Nwe. It comes from the pacemaker of the heart that’s the signal at that generates an action potential in the HL and the particular muscle action potential in the contract. It was inlet there’s a plateau, during which calcium enters the cell that is a voltage gated type calcium on the membrane of the teacher Calcium move along gradient entering the cellular calcium concentration rises. This calcium is insufficient to cause contraction on its own. What it does is it also triggers a calcium release channel on the surface of the plasma. This is calcium induced calcium release, so the calcium inside the cell has two extra cellular fluid and sarcoplasmic Calcium sliding over the thick short muscle at the end of the plateau calcium what happens to the calcium inside the ions pumped out of the circle plasm into the circle plasm reticulum and out into the cellular space plasma reticulum has a calcium uses ATP calcium against its gradient inside the plasma is the Kho Kho plasmic, endoplasmic reticulum calcium ATP Plasmic membrane which plasma membrane has calcium sodium along it gradient would enter the cell in exchange for calcium leaving the cell so you can see how calcium gets out of the cell through this exchanger that sodium is gonna be pumped out by sodium potassium ATP, so the calcium level in the cell comes back down again, and when another action potential arrives, the process repeats That in the cardial cell depends on the intra cellular calcium concentration ability of the myocardial cells to contract and generate force is contractility. If there’s increased calcium through the calcium &channels, there’s more cellular calcium so there’s increased contract. There’s increased calcium into plasma reticulum and there’s more calcium being stored which can get released during the next contraction again increasing contract. This can happen with phosphorylation of these channels with sympathetic stimulation Remember that the hardest applied by autonomic nerves the sympathetic parasympathetic nervous system sympathetic stimulation increase contract, said a positive ironic effect is the term that used for contract so More contract means a positive tropic effect parasympathetic opposite effect has a negative tropic reduces contractibility more, so in the Than in the ventricles cause, they innovate the atrium more This other factors which can either increase or decrease cardiac contract and this contract together with preload, and after our important factors that determines stroke volume of the heart and the cardiac output muscle