The cell membrane is like a shield that keeps the inside of the cell balanced and safe. This balance is called homeostasis.

Think of the cell membrane as a flexible layer made up of different parts, just like a mosaic art piece. Here are the main components:

• Phospholipids: These are the main building blocks of the membrane. They create a double layer where the tails, which don't like water, point inward. Meanwhile, the heads, which love water, face outward. This setup creates a barrier that allows some things to get through but keeps others out.

• Proteins: These are found within the phospholipid layer. They have different jobs, like helping move important materials in and out of the cell. This is super important for getting nutrients and getting rid of waste.

• Cholesterol: This helps keep the membrane stable. It makes sure that the membrane stays flexible, which helps it stay strong.

Thanks to these parts, the cell membrane lets some substances go in and out while blocking others. This ability, called selective permeability, helps the cell take in nutrients and get rid of waste, keeping everything working smoothly.