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why do we need muscles and joints

What is the purpose and structure of the skeleton? 1. Supports and protects the softer parts of the body (the very important organs! )P
The brain is protected by the skull. The heart and lungs are protected by a strong rib cage. It is also protected by the breast bone (sternum) at the front and vertebral spinal column at the back. The spinal cord is protected by the vertebrae (bones of the spine). The intestines and reproductive organs are protected by the pelvis. 2. Supports our body through a framework of bones. Bones are not solid. The hard outer layer of the bone protects the light, porous (not solid) bone inside. This porous bone contains the marrow, which is the factory where red blood cells are produced a process called haematopoiesis. Red blood cells carry oxygen around the body, providing energy for our muscles. However, before we are born, all of our bones begin as a rubbery material called cartilage. As we grow, more and more deposits of calcium are laid down which change some of the cartilage into a more solid and rigid mass bone. act as an anchor for muscles which together, along with other soft tissues, make the body move. contain calcium and other minerals which make them hard (rigid) and provide strength. supply the body with calcium when the diet is calcium deficient. 3. Prevents the body from losing its shape. P 4. Suspends some of the vital organs, preventing them from crushing each other. 5. Helps keep the calcium levels in the blood constant. Calcium is essential for the functioning of all the cells in the body, in particular the bones, brain and muscles. Without enough calcium, these cells do not operate properly. The body needs a constant level of calcium. If there is not enough calcium in the blood then cells called osteoclasts dissolve calcium from the bones. The appendicular skeleton refers to your arms and legs.

It is called appendicular, from append because they are attached by girdles, which bridge each with the main body. How do our bones move? Bones cannot move without muscles. Most muscles (like those in our arms and legs) work in pairs one muscle contracts as the other one relaxes. The bone is pulled towards the contracted muscle. Muscles are attached to bone by tendons. How are bones joined together? The place where two or more bones meet is called a joint. P Some joints are fixed as in the skull, but others can move such as where the bones in the leg meet. (See Joints. )P At these joints, ligaments hold the bones together. Can bones bend? Bones in the body do not bend but break when abnormal pressure is placed on them. There is an exception to this and that is in a small child, called a greenstick fracture because it looks like a green rather than dry stick has tried to be broken. The muscular system is what allows your body to move. Muscles are necessary for little movements, like smiling, and for big movements, such as running or throwing. Some muscles you control, like your bicep when youвre lifting something heavy. Other muscles, such as those that help you breathe, move without you thinking at all. In addition to being responsible for movement, the muscular system is also what keeps your body in whatever position itвs in against the pull of gravity. But thereвs much more to your muscles than that. To find out more about the muscular system, check out these 14 fun facts. 1. Muscles are divided into three types: smooth, cardiac, and skeletal Smooth muscles are the involuntary muscles in your gut, blood vessels, and elsewhere that work without you consciously thinking about making them move. Cardiac muscles are in your heart. Skeletal muscles are attached to the bone and help you with everyday activities ranging from sitting and standing to walking, typing, and doing housework. 2.

Your body contains more than 600 muscles These include the muscles you can feel in your arms and legs, as well as muscles deep inside your body, like the one that keeps your heart beating and those that help you digest food. By comparison, your body has. 3. Muscles are made up of special cells called muscle fibers Their main quality is contractibility, which means the muscles can shorten or lengthen as needed. Almost all movement in your body happens because of muscle contractibility. 4. The largest muscle in the body is the gluteus maximus Itвs the main extensor muscle of the hip, though you may know it as the large muscle in the buttocks. Itвs the largest muscle in the body because its main job is to support your trunk and maintain proper posture. The gluteus maximus is the main muscle used to help you walk upstairs. 5. The smallest muscles in the body are in your inner ear They include the tensor tympani and the stapedius. They connect to your eardrum and hold your inner ear together. The smallest bones in the body are also in your ear. 6. The strongest muscle, based on its size, is the masseter Itвs a muscle in your jaw. It can close your teeth with a force as great as 200 pounds on your molars. 7. Muscles are attached to bones by tendons Understanding the difference between tendons and ligaments can be confusing. In addition to attaching muscles to bones, tendons can also attach muscles to parts of your body such as your eyeballs. Ligaments connect one bone to another in your joints. 8. Muscles make up about 40 percent of your total body weight This is for most vertebrates. 9. The hardest working muscle in the body is the heart On an average day, it pumps about. 10. Some of your busiest muscles are those controlling eye movements These muscles are constantly making adjustments as you read, watch TV, or look around you.

In an hour of reading, your eyes may make as many as. 11. Most of the heat produced in your body comes from muscle contraction Muscle movement counts for almost produced inside the body. When youвre cold, your muscles contract involuntarily. When you shiver, those are muscles trying to warm your body. 12. The motor cortex on one side of your brain controls muscle movement on the other side of the body The motor cortex on the right side of your brain controls the muscles on the left side of the body, while the motor cortex on the left side controls the muscles on your right side. The brain sends movement signals through the spinal cord and out through the peripheral nervous system in your muscles. The messages from the brain become more complex when there are more muscles involved in an activity, such as shooting a jump shot in basketball. 13. Muscles usually work in pairs When one shortens, its corresponding muscle lengthens. Think about doing bicep curls. When you curl your arm up so the bicep is shorter, the tricep on the other side of your arm is straightened out. 14. Muscles canвt push. They can only pull. When youвre pushing a door open, for instance, your muscles are actually pulling your elbow and shoulder against the door. No matter what youвre doing, you have muscles at work. But to keep them healthy, they need exercise. Even your heart needs a workout to stay strong, which is why aerobic exercise that gets your heart rate up is so important. The muscles in your arms, legs and elsewhere need exercise, too. As you age, you start to lose muscle mass. But if you exercise your muscles with strength training and resistance exercises, you can slow down that process and maintain a mighty muscular system for a long time. And thatвs a fact.

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