why do we need bones and muscles

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. Bones. The skeleton acts like a shield for our vital organs, such as our brain and heart. The skull protects the brain, the ribcage protects the lungs and heart, and the backbone wraps all the way around the spinal cord. Ligaments connect bones to other bones. Bone density measures how healthy a bone is Б it shows how much mineral matter there is in a square centimetre of bone.


Bone marrow is a tissue found inside bones. Bone marrow is part of the lymphatic system, which plays an important role in the immune system Б how our body fights diseases. Bones have three parts The periosteum is a thin membrane on the outer surface Б it contains the boneБs nerves and blood vessels. Underneath this is cortical bone Б also called compact bone Б which is smooth and hard. Cancellous bone is located in layers within compact bone Б itБs sometimes called spongy bone because it has little holes in it. There are six different kinds of fractures: complete, greenstick, single, comminuted, bowing and open. Doctors use x-rays to help them decide how to set the broken bones so they can join back up with new cells and blood vessels. Bones need calcium to keep healthy. Calcium can be found in dairy products, dark green leafy vegetables, nuts, orange juice and soy. Vitamin D helps the body and bones absorb calcium Б fish and egg yolks both have vitamin D in them. Muscles. There are three kinds of muscles Б smooth, cardiac and skeletal. Smooth muscles and cardiac muscles are also called involuntary muscles, because they move without you telling them to. Skeletal muscles are also called voluntary muscles, because you can control when you move them. When muscles feel sore, it can be because of a strain Б the muscle fibres have torn a bit and need time to heal. This happens if youБve picked up something very heavy, or if youБve been doing a lot of running and jumping.


Another type of muscle injury is a sprain Б this happens when a tendon is pulled. There are four main muscle shapes Spindle-shaped muscles, which are thick in the middle and thinner at the ends, such as your biceps and triceps in your arm Flat muscles, such in your forehead Triangular muscles, such as the deltoid muscles in your shoulder Circular muscles, which are shaped like rings, such as around your mouth biceps calcium cancellous bone Б a type of bone is located within layers of compact bone, and is sometimes called spongy bone because it has tiny holes in it compact bone Б the smooth, hard part of the bone underneath the periostium, which is what youБll see when you look at a skeleton deltoid fracture Б the term for a broken bone; there are six different kinds of fractures: complete, greenstick, single, comminuted, bowing and open involuntary muscles Б muscles that you do not control, such as in your heart and stomach ligaments osteoporosis Б a disease that causes bones to lose density, making them more likely to break pelvis periostium Б the thin membrane covering the outside of the bone, containing nerves and blood vessels ribcage skeletal muscles skull sprain strain Б a muscle injury that can make them feel sore if youБve picked up something very heavy, or done more running than youБre used to. tendons vertebrae vitamin D voluntary muscles Б muscles that you can control moving, such as the ones in your arms and legs

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