Brain
Your brain runs everything you do: thinking, remembering, moving, breathing, sleeping and making sense of what you see, hear, touch, taste and smell. It sends and receives messages through nerves that reach every part of your body.
Thyroid
A small, butterfly-shaped gland at the front of your neck. Its hormones set how fast your body uses energy, which affects your heart rate, your weight, how warm or cold you feel and how much energy you have.
Lungs
Your lungs bring oxygen into your body and take carbon dioxide out. Air travels down tiny branching tubes to millions of small air sacs, where oxygen passes into your blood.
Heart
A muscle about the size of your fist that pumps blood around your body, carrying oxygen and nutrients to every cell. Its right side sends blood to the lungs; its left side pumps it out to the rest of the body.
Liver
Your largest internal organ. It cleans your blood of waste and medicines, makes bile to help digest fat, stores energy as sugar, and makes proteins your blood needs to clot.
Gallbladder
A small pouch tucked under the liver. It stores bile and squeezes it into the small intestine when you eat, to help digest fat.
Stomach
A stretchy bag that mixes the food you swallow with acid and enzymes and churns it into a thick liquid, which it then lets out, a little at a time, into the small intestine.
Spleen
An organ on your upper left side, behind the stomach. It filters your blood, removes old red blood cells and helps your body fight some infections.
Pancreas
A long gland behind the stomach. It makes juices that help digest food, and the hormones insulin and glucagon, which keep the sugar in your blood at the right level.
Kidneys
Two bean-shaped organs, each about the size of a fist, below your ribs on either side of your back. They filter your blood, removing waste and extra water as urine, and help control your blood pressure.
Small intestine
A long, coiled tube where most of your food is broken down and its nutrients are taken into your blood.
Large intestine
The last part of the digestive system. It takes water back out of what is left of your food and turns it into stool.
Bladder
A stretchy, balloon-like bag low in your belly that stores urine from the kidneys until you go to the toilet.
Skin
Your largest organ. It keeps germs out and water in, helps keep your temperature steady by sweating, and lets you feel touch, pressure, heat, cold and pain.
Bones
An adult skeleton has 206 bones. They hold you up, protect organs like the brain and heart, store calcium, and make blood cells in the marrow inside them.