The nervous system communicates through electrical impulses and the communication is very fast. It works in a relay fashion, from point to point comparable to the way the old telephones systems used to work.
The endocrine system communicates by chemical signals via the bloodstream. Hormones are secreted into the blood and extra cellular fluids, then transported to target cells, which must bear a receptor to be able to bind to a specific hormone, and respond.
Hormones are chemical messengers secreted into blood or extracellular fluid that affect the function of other cells.
Endocrine communication is not quite as fast as the nervous system communication
100,000 years ago is your answer
It is an explosive cell that is used for protection from predators or prey hunting by the species of the phylum Cnidaria
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To reach and fertilize an egg, sperm must move — wriggling and swimming through a woman's cervix, uterus and fallopian tubes. This is known as motility. You're most likely to be fertile if at least 40% of your sperm are moving.
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