Moving and Growing

1. Moving and Growing

2. Endoskeletons The human endoskeleton We need an endoskeleton to hold us up right and if we did not have an endoskeleton we would just be a giant blob on the floor. It protects the organs and provides a system of levers on which the muscles can act to produce movement. We already hinted at the purpose of a skeletal system. Protection and support are the two big reasons that organisms have skeletal systems

3. Endoskeletons An endoskeleton is on the out side.

4. muscles Did you know you have more than 600 muscles in your body? They do everything from pumping blood throughout your body to helping you lift your heavy backpack. You control some of your muscles, while others — like your heart — do their jobs without you thinking about them at all. Muscles are all made of the same material, a type of elastic tissue (sort of like the material in a rubber band). Thousands, or even tens of thousands, of small fibers make up each muscle.Youhave three different types of muscles in your body: smooth muscle, cardiac (say: KAR-dee-ak) muscle, and skeletal muscle. Smooth Muscles Smooth muscles — sometimes also called involuntary muscles — are usually in sheets, or layers, with one layer of muscle behind the other. You can't control this type of muscle. Your brain and body tell these muscles what to do without you even thinking about it. You can't use your smooth muscles to make a muscle in your arm or jump into the air. But smooth muscles are at work all over your body. In your stomach and digestive system, they contract (tighten up) and relax to allow food to make its journey through the body. Your smooth muscles come in handy if you're sick and you need to throw up. The muscles push the food back out of the stomach so it comes up through the oesophagus (say: IH-SAH-FUH-GUS) and out of the mouth. Smooth muscles are also found in your bladder. When they're relaxed, they allow you to hold in urine until you can get to the bathroom. Then they contract so that you can push the urine out. These muscles are also in a woman's uterus, which is where a baby develops. There they help to push the baby out of the mother's body when it's time to be born. You'll find smooth muscles at work behind the scenes in your eyes, too. These muscles keep the eyes focused

5. Joints The bones of the skeleton function as a system of levers that move around pivot joints by the alternate contraction and relaxation of muscles. Muscles are paired around a joint, so that every group of muscles that moves a bone in one direction has an opposite group of muscles that move the bone in the opposite direction smooth movement of the body. As one muscle contracts, the corresponding muscle relaxes. For example, the muscles of the upper arm form an antagonistic pair. When you contract your biceps muscle, your triceps muscle relaxes, and your arm bends at the elbow. When you contract your triceps muscle, your biceps relaxes and your arm straightens. The two movements performed by the elbow joint are flexion and extension. Flexion occurs when the biceps contracts and brings the forearm towards the upper arm. Extension occurs when the triceps contracts and straightens the arm. Muscles are attached to the bones by strong tendons. The top of the biceps is attached to the shoulder blade by two tendons, the bottom is attached to one of the bones of the forearm. The points of attachment are fixed and do not move, so that when the biceps muscle contracts and shortens in length, it pulls the forearm.

6. Hinge The body has three main joint types: joints that are fixed, or that do not move, such as the seams between the pieces of bone that make up the skull; joints that have limited movement, such as those in the spine; and joints that allow a good deal of movement, such as those at the knee, elbow

7. Invertebrates Invertebrates were the first animals to evolve. Fossil evidence of invertebrates dates back to the late Precambrian, 600 million years ago. Invertebrates evolved from single-celled microorganisms. Since then, invertebrates have diversified into countless forms. An estimated 97 percent of all species are alive today are invertebrates. Invertebrates do not have a back bone. Invertebrates include animal groups such as sponges, cnidarians, flatworms, molluscs, arthropods, insects, segmented worms, and echinoderms as w the have an exoskeleton as many other lesser-known groups of animals. They are sea creatures as well as land creatures. All insects are invertibrates.