SR is the site of storage and release of calcium ions for contraction. Three types of cardiocytes are found in the myocardium. 1) Cells found at the junction of the great veins and the right atrium have the fastest intrinsic rhythm (this is the sinoatrial (SA) node or 'pacemaker' of the heart). These are the AUTORHYTHMIC CELLS and they spontaneously discharge about 100 times per minute.
1 Higher contribution limits are permitted with a Roth Individual 401k than a Roth IRA. 2  For 2015 participants can contribute up to $18,000 to a Roth 401k ($24,000 if age 50 or older), but they can only contribute $5,500 ($6,500 if age 50 or older) into a Roth IRA.
Roth IRA. The contribution amount limits to a Roth IRA are the same as those to a traditional IRA. However, your eligibility to contribute to a Roth IRA depends on your income. You can make a full contribution to each Roth IRA as long as your working spouse makes less than $173,000 in 2012.At those levels of modified AGI, the contribution amount begins to phase out, and at $183,000 (2012) you are no longer eligible to make contributions.he maximum IRA contribution limit is $5,000 for those under the age of 50. For those 50 and older, the contribution limit is $6,000. This contribution limit applies to all IRAs held in each personâs name. Since IRAs canât be held jointly, a married couple can contribute the maximum amount to two IRAs.