Cell membranes are primarily made up of phospholipids, which form a bilayer that serves as a barrier and structure for the membrane. Additionally, proteins are embedded within the phospholipid bilayer and play various roles, such as signaling and transport.
Hormones, particularly steroid hormones, are synthesized from cholesterol, which is a type of lipid. Cholesterol is also an important component of cell membranes, contributing to their fluidity and stability.
In summary, cell membranes are composed of phospholipids and proteins, while hormones like steroids are created from cholesterol.