Polydactylism occurs . a. only in cats b. only in humans c. in less than one in 1000 children d. more commonly in certain populations, such as the Amish.

i think the answer is composed of atoms

these muscles maintain the blood pressure in the vessels. the smooth muscles are innervated by nerves of the autonomic nervous system. when the muscles contract, they cause vasoconstriction of the vessels and increase blood pressure. when the muscles relax, they enable vasodilation of the   blood vessels hence reduce blood pressure.