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Health Information For Parents
Bones provide support for our bodies and help form our shape. Although they’re very light, bones are strong enough to support our entire weight.
Bones also protect the body’s organs. The skull protects the brain and forms the shape of the face. The spinal cord, a pathway for messages between the brain and the body, is protected by the backbone, or spinal column. The ribs form a cage that shelters the heart and lungs, and the pelvis helps protect the bladder, part of the intestines, and in women, the reproductive organs.
Bones are made up of a framework of a protein called collagen, with a mineral called calcium phosphate that makes the framework hard and strong. Bones store calcium and release some into the bloodstream when it’s needed by other parts of the body. The amounts of some vitamins and minerals that you eat, especially vitamin D and calcium, directly affect how much calcium is stored in the bones.
Bones are made up of two types of bone tissues:
In this soft bone is where most of the body’s blood cells are made. The bone marrow contains stem cells, which produce the body’s red blood cells and platelets, and some types of white blood cells. Red blood cells carry oxygen to the body’s tissues, and platelets help with blood clotting when someone has a cut or wound. White blood cells help the body fight infection.
Bones are fastened to other bones by long, fibrous straps called ligaments (LIG-uh-mentz). Cartilage (KAR-tul-ij), a flexible, rubbery substance in our joints, supports bones and protects them where they rub against each other.
The bones of kids and young teens are smaller than those of adults and contain “growing zones” called growth plates. These plates consist of multiplying cartilage cells that grow in length, and then change into hard, mineralized bone. These growth plates are easy to spot on an X-ray. Because girls mature at an earlier age than boys, their growth plates change into hard bone at an earlier age.
Bone-building continues throughout life, as a body constantly renews and reshapes the bones’ living tissue. Bone contains three types of cells:
Muscles pull on the joints, allowing us to move. They also help the body do such things as chewing food and then moving it through the digestive system.
Even when we sit perfectly still, muscles throughout the body are constantly moving. Muscles help the heart beat, the chest rise and fall during breathing, and blood vessels regulate the pressure and flow of blood. When we smile and talk, muscles help us communicate, and when we exercise, they help us stay physically fit and healthy.
Humans have three different kinds of muscle:
The movements that muscles make are coordinated and controlled by the brain and nervous system. The involuntary muscles are controlled by structures deep within the brain and the upper part of the spinal cord called the brain stem. The voluntary muscles are regulated by the parts of the brain known as the cerebral motor cortex and the cerebellum (ser-uh-BEL-um).
When you decide to move, the motor cortex sends an electrical signal through the spinal cord and peripheral nerves to the muscles, making them contract. The motor cortex on the right side of the brain controls the muscles on the left side of the body and vice versa.
The cerebellum coordinates the muscle movements ordered by the motor cortex. Sensors in the muscles and joints send messages back through peripheral nerves to tell the cerebellum and other parts of the brain where and how the arm or leg is moving and what position it’s in. This feedback results in smooth, coordinated motion. If you want to lift your arm, your brain sends a message to the muscles in your arm and you move it. When you run, the messages to the brain are more involved, because many muscles have to work in rhythm.
Muscles move body parts by contracting and then relaxing. Muscles can pull bones, but they can’t push them back to the original position. So they work in pairs of flexors and extensors. The flexor contracts to bend a limb at a joint. Then, when the movement is completed, the flexor relaxes and the extensor contracts to extend or straighten the limb at the same joint. For example, the biceps muscle, in the front of the upper arm, is a flexor, and the triceps, at the back of the upper arm, is an extensor. When you bend at your elbow, the biceps contracts. Then the biceps relaxes and the triceps contracts to straighten the elbow.
Joints are where two bones meet. They make the skeleton flexible — without them, movement would be impossible.
Joints allow our bodies to move in many ways. Some joints open and close like a hinge (such as knees and elbows), whereas others allow for more complicated movement — a shoulder or hip joint, for example, allows for backward, forward, sideways, and rotating movement.
Joints are classified by their range of movement:
Three kinds of freely movable joints play a big part in voluntary movement:
Injuries to growth plates, which produce new bone tissue and determine the final length and shape of bones in adulthood, must be treated so that bones heal properly.
A hamstring strain happens when one or more of the muscles in the back of the leg gets stretched too far and starts to tear. Find out how to treat hamstring strains in this article for teens.
What’s a sprain? What’s a strain? Find out in this article for kids.
Here’s what to do if you think your child has pulled or torn a muscle, ligament, or tendon.
A broken bone needs emergency medical care. Here’s what to do if you think your child just broke a bone.
It’s not always easy to tell if you have a stress fracture, and stress fractures can get worse quickly. This article explains how to prevent and treat them.
Watch a movie about your bones.
Does your child sometimes wake up crying in the middle of the night complaining of throbbing leg pain? It could be growing pains.
Growing pains are for real. Usually they happen when kids are between the ages of 3 and 5 or 8 and 12.
What happens when you break a bone?
Scoliosis makes a personâs spine curve from side to side. Large curves can cause health problems like pain or breathing trouble. Health care providers treat scoliosis with back braces or surgery when needed.
Sprains and strains are common injuries, especially for people who play hard or are intoÂ sports. Find out what they are and how to recuperate from one.
Bones are tough stuff – but even tough stuff can break. Find out what happens when a bone fractures.
Many kids will have a broken bone at some point. Here’s what to expect.
Some injuries will heal best if a cast is used. Find out how they work and how to take care of them in this article for kids.
Our bones, muscles, and joints form our musculoskeletal system and enable us to do everyday physical activities.
If the tendon just above your heel becomes swollen or irritated due to overuse, it can lead to a painful condition called Achilles tendonitis. Find out how to treat it – and prevent it.
We build almost all our bone density when we’re kids and teens. Kids with strong bones have a better chance of avoiding bone weakness later in life. Here’s how parents can help.
Broken bones have an amazing ability to heal, especially in kids. Here’s how.
Broken bones have an amazing ability to heal. New bone forms within a few weeks of the injury, although full healing can take longer.
Broken bones have an amazing ability to heal, especially in kids. Full healing can take time, but new bone usually forms a few weeks after an injury.
A buckle or torus fracture is a type of broken bone. One side of the bone bends, raising a little buckle, without breaking the other side of the bone.
A buckle or torus fracture is a type of broken bone. One side of the bone bends, raising a little buckle, without breaking the other side of the bone. Teens don’t usually get this type of fracture.
Casts keep bones and other tissues in place while they heal. Here’s what to expect, and how to care for casts.
This article for teens has tips on taking care of a cast so it keeps working as it should.
Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor.
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