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.
Cardiac output can be increased by increasing the heart rate. Thus an increase in temperature, through the vasodilation of blood vessels causes a drop in blood pressure, which is compensated for by increasing the cardiac output, which can be achieved through increasing the heart rate.eart rates tend to be lower in the morning. Heart rate increases  at high temperatures. Dehydration causes an increase in heart rate.  Heart rate during running varies by a â¦ few beats from day-to-day.  Training heart rate does not predict racing heart rate.