Summary
The human body works thanks to several systems acting together. The digestive system turns food into nutrients; the respiratory system takes oxygen from the air and expels carbon dioxide; and the circulatory system, with the heart and blood, delivers those nutrients and that oxygen to every cell.
Other systems complete the job. The nervous system, led by the brain, receives information from the senses and gives orders; the excretory system removes waste through the kidneys; and the locomotor system, made of bones and muscles, holds the body up and allows movement. All of them are made of organs, and each organ of tissues and cells.
Key points
- The body is organised into systems, each with a function.
- Digestive: turns food into nutrients (mouth, stomach, intestines).
- Respiratory: exchanges oxygen and carbon dioxide in the lungs.
- Circulatory: the heart pumps the blood, which delivers oxygen and nutrients.
- Nervous: the brain coordinates the body and processes what the senses pick up.
- Excretory: the kidneys filter the blood and form urine.
- Locomotor: bones hold the body up and muscles move it.