The Endocrine System. As noted earlier, the endocrine system is not a part of the nervous system, but it is still essential to communication throughout the body. This system is composed of glands, which secrete chemical messengers known as hormones.
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Answer:
Hair and nails are mostly made of protein. Your body uses protein to build and repair tissues. You also use protein to make enzymes, hormones, and other body chemicals. Protein is an important building block of bones, muscles, cartilage, skin, and blood.
Explanation:
I agree with the first answer