(iStock images/The Washington Post illustration)

Your body works thanks to cells — trillions of them — doing their jobs. Some make chemicals to fight infection. Others make tears to protect your eyes. Still others make proteins to help you grow.

You might ask how this happens. To understand, think of cells as microscopic factories.

Factories typically contain people, machines and raw materials. Supplies are brought into the factory. Workers use the supplies to build whatever products the factory makes. Machines in the factory play different roles in that process. Everything works together to make products customers need.

Cells get raw materials — including water, oxygen, minerals and other nutrients — from the foods you eat. They let in raw materials through the cell membrane: the thin, elastic structure that forms the border of each cell.

Cells have internal structures called organelles. Each organelle is like a worker or a machine that has a job to do for the cell to function properly. Here are some of them.

● The nucleus is like a “foreman,” or person in charge, because it controls cell function. It contains DNA (deoxyribonucleic acid), the master organizer for how cells work.

● Mitochondria are the “batteries” in your cells. Chemical reactions within the mitochondria create the energy that powers cell functions.

● Lysosomes are fluid-filled vesicles, or sacs, that act as a waste-disposal system for cells. Like a hungry Pac-Man, lysosomes eat bacteria and unwanted material in the cell. They contain enzymes that “digest” anything they absorb to make it harmless.

● Ribosomes are the cell’s molecule makers. They assemble proteins from amino acids according to the blueprint in your DNA.

● The endoplasmic reticulum is a system of tubelike structures that’s essential for the production of proteins and lipids (fats).

● Once protein molecules have been made, they move to the Golgi apparatus for further processing. The Golgi apparatus is like a conveyor belt that “wraps” proteins inside vesicles so they can be “shipped” out of the cell.

To see how these “factory” parts work together, let’s look at the stomach.

In addition to making acid to digest food, your stomach contains mucus-producing cells that protect it from being damaged by the acid. The DNA in the cell’s nucleus instructs the ribosomes to make mucus. Once this is done, mucus is moved to the Golgi apparatus. The mucus is then packaged into vesicles that travel to the cell membrane, where it’s released, to coat the lining of your stomach.

As you take the last bite of your breakfast, keep the following fact in mind: If those tiny factories in the stomach stopped working, your body would be out of business. That’s because your stomach would digest itself along with your last meal.

Bennett is a Washington pediatrician.