The cells of a puppy and the cells of a dog are the same size. Why is a dog larger?

The Dog is has much more cells because it's bigger.

Explanation:

when a puppy grows up to be a dog, it gains more cells because it GROWS up and becomes bigger than the puppy's original size.

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.