Human body Organizing Systems Organs and tissues work in the body teams to carry out major tasks, like Your cells and tissues are transporting blood organized into larger body or processing food. These teams are parts called organs. In turn, called systems. your organs work together The heart is the largest to form body systems. organ in the blood system. It pumps blood around Kidney the body. Heart Brain The tubes that carry Organs blood away from the heart are called arteries (shown in An organ is a body part that red). does a specific job. Your heart’s The tubes that job, for instance is to pump carry blood back to the heart are called blood. Kidneys clean blood. veins (shown in blue). Heart and blood Organ transplant Your heart, blood, and If a vital organ stops working, doctors blood vessels make up may replace it with an organ from another the blood system. It person. This is called a transplant. transports vital supplies around your body. 10 Which body system makes your stomach rumble? Organizing the body Muscles Other systems Your muscle system is made of tissues that move parts Some of your other of your body by pulling important systems on them or squeezing are shown in this list. them. Your biggest muscles all pull Muscles change Breathing system: the the position of your main organs are your on bones. skeleton by pulling lungs, which take in air. different bones. Your fingers are moved by Hormone system: this muscles in your arm. uses powerful chemicals to control your body and mood. The most powerful muscles are Skin, hair, and nails: in your legs. these form your body’s protective covering. Immune system: this seeks and destroys germs that get into your body. Urinary system: this Skeleton cleans blood and gets rid of waste chemicals. Bones and joints make Reproductive system: up the skeletal these are the organs that system, an make babies. inner frame that supports Digestive system the body. Your digestive A quarter of your bones are organs break in your feet. down food to Nerves provide your Your nervous system carries body with energy electrical signals around and raw materials. your body. You need this system to see, Your mouth is the first Signals shoot part of the digestive along nerves to hear, think, system. muscles, and react. telling them when to pull. A long, twisting tube makes up your intestines, where Senses, such as digested food is touch, rely on absorbed. nerve cells that send signals to your brain. Your brain is the nervous system’s control centre. The digestive system. 11 12 Skeleton Skeleton Skull Smallest bone Around the same length Your bones all join up to as a grain of rice, this is one of the smallest and make a frame for your body bones in your body. It called the skeleton. This lies deep inside your ear. bones Jaw bone protects your insides, and helps you move about. How many ribs have you got? Shoulder blade A giraffe’s long neck helps it to eat leaves Each finger off tall trees. has three bones, except for your thumb, which has two. You have eight small bones in each wrist. 206 bones Neck bones There are 206 bones There are Did you know that you Rib 24 bones in have seven bones in your in an adult skeleton. your spine. neck, the same number Over half of these are found in as a giraffe? The top one the hands and feet – the parts allows you to move your of your body that perform the head up and down, the second lets you rotate it most complicated movements. Pelvis from side to side. The th Your tail bone is at the very bottom of your igh bone is the b spine. 24, unless you are one of the rare people born with 26. Frogs have very short spines to withstand the strain of the huge leaps they take. Thigh bone iggest Snakes are A fish’s incredibly bendy Long lasting spine allows it and strongest in thanks to many to bend its body from Bone is a very hard identical side to side so it can material and one of the last vertebrae forming swim smoothly. their long spines. parts to rot away when a body is buried. This woman lived in the Stone Age, 5000 Shin bone years ago, but her bones have survived until today. the body. Your ankle has Become three larger an expert... bones and four Other skeletons smaller ones. on bone and cartilage, Most animals have a pages 20-21 backbone and are called Skeleton on teeth, There are 54 bones in your “vertebrates”. Animals pages 84-85 hands, and 52 with no spine, like spiders in your feet. and bugs, are called 13 “invertebrates”.