The answer is transverse or t tubules. These invaginations into the skeletal muscles cells play a significant role in electrical conductivity of impulse across muscle or cardiac fibres. They regulate calcium concentration and it's release in ion channels hence enabling a forceful contraction of cardiac and muscle cells.
<span>About 50%
Both the mother and father contribute about the same amount of genetic material to their offspring, but it's not quite 50/50. Taking humans as an example, both parents contribute the same amount of genetic material for 22 of the 23 chromosome pairs, but the 23rd pair that determines gender (the X and Y chromosomes) are of different size. So for female children, both parents contribute about the same amount, but for male children, the mother contributes a larger portion since the X chromosome is quite a bit larger than the Y chromosome from the father. Another area in which the contribution differs is the mitochondrial DNA which is contributed solely by the mother. For mammals, this is about 1% of the total genetic material.</span>
45,000 people kill themselves out of 100,000 each year
Well, it depends on what type of materials you are using. You should always consult your teacher because if you are doing chemisty, for example, then if you just throw everything in a trachcan, you never what elements or substances can react together.
B. the circulatory system
