Describe the composition of the plasma membrane.

the plasma membrane is constructed of phospholipids which consist of fatty acids and alcohol. They also have other lipids and proteins on the outside

Explanation: Hope this helps :)

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.