Organs and organ systems

Run, Lina! You’ll catch the bus! Lina made it. Now she is breathless. She feels her lungs filling and emptying of air faster than usual, to provide the body with oxygen.

And her heart is beating harder, to pump blood and oxygen faster around her body. That’s what the heart and the lungs do: They oxygenate the blood and pump it around the body. A body part with a distinct shape and a defined task is an organ. An organ consists of tissue, and the tissue consists of billions of cells. In your body there are lots of organs, like the heart and the lungs, brain, liver, and kidneys.

These are found inside the body, so we call them inner organs. There are also organs on the outside of your body, like skin or ears. These are examples of outer organs. Some organs only have one task, while others have many. In order for your body to function properly, the organs need to cooperate.

Two or more organs which cooperate to carry out a task form an organ system. The brain is an organ which controls the rest of the body’s organs and organ systems. The brain cooperates with the spinal cord and the nerve cells. Together they form the nervous system. The nervous system is an organ system which, among other things, receives signals from the outer world, to make sure that your heart pumps, and that you breathe even when you sleep.

The brain takes care of all this by itself. You never have to think about how it’s done. Also, different organ systems cooperate with each other. Think about Lina’s breathing. The brain makes sure she breathes.

Her lungs are filled with air, and the air contains the oxygen that her body needs. The lungs absorb the oxygen from the air and oxygenate the blood. The blood transports the oxygen. The heart, in turn, pumps the blood through blood vessels to all the cells of the body. The oxygen enters the cells, while carbon dioxide leaves the cells.

The blood transports carbon dioxide back to the lungs. There the gasses are exchanged and the blood absorbs oxygen again. The lungs send the carbon dioxide out into the air, and inhale oxygen again. Lina breathes. During this process, several organ systems cooperate, the nervous system, the breathing system and the blood system. “Next stop: Aorta Street!” Lina has arrived and it’s time to get off.

Now, her brain sends signals via the nerve cells to the muscle system. Two organ systems - the nervous system and the muscle system - are cooperating. The muscles start to work, and make Lina stand up and get off the bus.