Specifically, this topic is about the epithelial cells lining the small intestine. These cells are animal cells, and their function is to absorb nutrients as part of digestion. This is what epithelial cells look like under a light microscope:

The core components of cells are the outer membrane, the cytoplasm (substance inside which contains all other stuff) and the nucleus (contains DNA).

All the other stuff is made up of various components with specific functions – these are called organelles. The ones you must know about are:

• • Plasma membrane, including cell-surface membrane
  • Microvilli
  •  Nucleus
  •  Mitochondria
  •  Lysosomes
  •  Ribosomes
  •  Endoplasmic reticulum
  •  Golgi apparatus

Here is a bit of information about each…

Plasma membrane

Plasma membrane is the thin boundary between cell and environment. It is made of a phospholipid bilayer, and its function is to control what passes through the cell. Membranes are also found in other organelles such as the nucleus and mitochondria.