During acclimatization over a few days to weeks, the body produces more red blood cells to counteract the lower oxygen saturation in blood in high altitudes. Full adaptation to high altitude is achieved when the increase of red blood cells reaches a plateau and stops.Heart rate is controlled by the two branches of the autonomic (involuntary) nervous system. The sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). ... At the beginning of exercise, your body removes the parasympathetic stimulation, which enables the heart rate to gradually increase.
D)all of them
Once an egg is fertilized by a sperm, a zygote is formed. The zygote divides into multiple cells in a process known as cleavage, triggering the beginning of embryonic differentiation. ... Cells in these three layers will give rise to different parts of the organism. The endoderm eventually becomes the gut.Mar 3, 2011
probably evolution?????????
