However, they are absorbed, usually as methyl mercury, by algae at the start of the food chain. This algae is then eaten by fish and other organisms higher in the food chain. Fish efficiently absorb methyl mercury, but excrete it very slowly. Methyl mercury is not soluble and therefore not excreted.
For example, a 10- to 15-minute brisk walk typically elevates the heart rate to 110 to 120 beats per minute. Also, the sinus node increases the heart rate when the body is stressed because of illness. In all of these circumstances, the heart rate increase is a normal response. Likewise, the sinus node signals the heart to slow down during rest or relaxation.
Since your bloodstream is responsible for bringing the oxygen to your muscles, your heart needs to pump a great amount of blood for maintaining the oxygen supply to the muscles that are working. To fulfill this goal, the heart starts beating rapidly and forcefully, which increases the heartbeat. In addition to that, if you are exercising on a hot day, then too, the high temperature coupled with the vigorous activity performed by your heart will result in an abnormal increase in your heart rate.