SECTION 2 THE SKELETAL SYSTEM

WHAT THE SKELETAL SYSTEM DOES? The skeleton has five major functions. It provides shape and support, enables you to move, protects your organs, produces blood cells and stores minerals and other materials until your body needs them.

SHAPE AND SUPPORT The skeleton determines the shape of the body, the backbone or vertebral column, is the center of the skeleton. If you move your fingers down the center of your back you can feel the 26 small bones or vertebrae that make up your backbone.

MOVEMENT AND PROTECTION The skeleton allows you to move, most of the body’s bones are associated with muscles pull on the bones to make the body move. Bones also protect many organs of your body, for example the skull protects your brain.

PRODUCTION AND STORAGE SUBSTANCES Some of your bones produce substances that your body needs. Bones also store minerals such as calcium and phosphorus. When the body needs the minerals, the bones release small amounts of them into the blood.

JOINTS OF THE SKELETON A joint is a place in the body where two bones come together. Joints allow bones to move in different ways. There are two kinds of joints: IMMOVABLE and MOVABLE = = -- -

IMMOVABLE JOINTS Some joints in the body connect bones in a way that allows little or no movement. The bones of the skull are heald together by immovable joints.

MOVABLE JOINTS They are joints are held together by strong connective tissues called ligaments. Most joints have a second type of connective tissue called cartilage, which is more flexible than bones. Cartilage covers the ends of the bones and keep them for rubbing against each other.

BONES – STRONG AND LIVING Bones are complex living structures that undergo growth and development.

BONE STRUCTURE The femur is the longest body bone, and it connects the pelvic bones to the lower bones. The blood vessels and nerves enter and leave the bone through the membrane. Beneth the bones outer membrane is a layer of compact bone.

BONE STRUCTURE The Compact bone is a hard and dense but not solid layer. Small canals run through the compact bone , these canals carry blood vessels and nerves from the bone’s surface to the living cells within the bone.

BONE STRUCTURE Inside the femur’s compact bone is a layer of spongy bone that is like a sponge with many small space within it. This structure makes spongy bone tissue lightweight but strong. Spongy bone is also found at the ends of the bone.

BONE STRUCTURE The spaces in many bones contain a soft, connective tissue called Marrow, there are 2 types of marrow. RED BONE MARROW Produces some of the body’s blood cells. YELLOW BONE MARROW Stores fat that can serve as an energy reserve.

BONE STRENGHT Bones are so strong, that they can absorb more force without breaking, bones are hard because they contain minerals (phosphorous and calcium).

BONE GROWTH bones are alived and they contain tissues, such as blood and nerves, because they are alive, bones also form new bone tissue as people grow. Some time new bone tissue forms after an accident.

BONE DEVELOPMENT The replacement of cartilage by bone tissue usually is complete by the time people stop growing.

TAKING CARE OF YOUR BONES A Combination of a balanced diet and regular exercise are important for a lifetime of healthy bones.

TAKING CARE OF YOUR BONES DIET: Includes enough calcium and phosphorous to keep your bones strong. Meats, grains and leafy vegetables are all good sources of calcium and phosphorous.

TAKING CARE OF YOUR BONES EXERCISE: During activities such as running, skating or dancing the bones support the weight of the entrire body, these activities help your bones grow strong and denser.

TAKING CARE OF YOUR BONES OSTEOPOROSIS: As people become older, their bones begin to lose some of the minerals they contain and this loss can lead to osteoporosis, a condition within the bones become weak and break easily.