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.
Best Answer: An increased heart rate means that the heart is doing more work on the blood. This means that the heart is creating more carbon dioxide at a higher heart rate. Increased carbon dioxide in the blood does not increase the heart rate.It does increase the respiratory rate. There is a group of neurons in the fourth ventricle of the brain that senses the pH of the cerebrospinal fluid. A drop in the pH results in an increase in the respiratory rate.est Answer: An increased heart rate means that the heart is doing more work on the blood. This means that the heart is creating more carbon dioxide at a higher heart rate. Increased carbon dioxide in the blood does not increase the heart rate. It does increase the respiratory rate.