The Skeletal System


How to Keep Your Skeletal System Healthy
Why Are Bones Important to the Body? Vitamin D increases the absorption of calcium and phosphorus in your small intestine and ensures that the minerals are available in your bloodstream. For example, phosphorus supports your skeletal system, but eating more does not necessarily make your bones stronger. Skin, Hair and Nail Health. Bone tissue contains many different cell types that constantly resize and reshape bones throughout growth and adulthood. It helps to keep your calcium levels at a healthy balance and can especially benefit people who have osteoporosis, a disease characterized by weak, brittle bones.

Bone Structure and Function

Nutrition's Impact on the Skeletal System

Although bone tissue may look inactive at first glance, at the microscopic level you will find that bones are continuously breaking down and reforming. Bones also contain a complex network of canals, blood vessels, and nerves that allow for nutrient transport and communication with other organ systems. The human skeleton contains bones. It is divided into two main parts, the axial and appendicular.

To optimize bone health through nutrition, it is important to understand bone anatomy. The skeleton is composed of two main parts, the axial and the appendicular parts.

The axial skeleton consists of the skull, vertebral column, and rib cage, and is composed of eighty bones. The appendicular skeleton consists of the shoulder girdle, pelvic girdle, and upper and lower extremities, and is composed of bones. Bones are also categorized by size and shape. There are four types of bone: The longest bone in your body is the femur thigh bone , which extends from your hip to your knee.

It is a long bone and functions to support your weight as you stand, walk, or run. Your wrist is composed of eight irregular-shaped bones, which allow for the intricate movements of your hands.

Your twelve ribs on each side of your body are curved flat bones that protect your heart and lungs. Bones are composed of approximately 65 percent inorganic material known as mineralized matrix. This mineralized matrix consists of mostly crystallized hydroxyapatite. The other 35 percent of bone is organic material, most of which is the fibrous protein collagen.

The collagen fibers are networked throughout bone tissue and provide it with flexibility and strength. There is spongy bone, also called trabecular or cancellous bone, and compact bone, also called cortical bone Figure 2. The two tissue types differ in their microarchitecture and porosity. Trabecular bone is 50 to 90 percent porous and appears as a lattice-like structure under the microscope. It is found at the ends of long bones, in the cores of vertebrae, and in the pelvis.

Trabecular bone tissue makes up about 20 percent of the adult skeleton. The more dense cortical bone is about 10 percent porous and it looks like many concentric circles, similar to the rings in a tree trunk, sandwiched together Figure 2. Cortical bone tissue makes up approximately 80 percent of the adult skeleton. It surrounds all trabecular tissue and is the only bone tissue in the shafts of long bones.

The two basic tissue types of bones are trabecular and cortical. This photo shows normal left and degraded right trabecular spongy bone. Bone tissue is arranged in an organized manner. A thin membrane, called the periosteum, surrounds the bone. It contains connective tissue with many blood vessels and nerves. Lying below the periosteum is the cortical bone. In some bones, the cortical bone surrounds the less-dense trabecular bone and the bone marrow lies within the trabecular bone, but not all bones contain trabecular tissue or marrow.

Bone tissue contains many different cell types that constantly resize and reshape bones throughout growth and adulthood.

Bone tissue cells include osteoprogenitor cells, osteoblasts, osteoclasts, and osteocytes. The osteoprogenitor cells are cells that have not matured yet. Once they are stimulated, some will become osteoblasts, the bone builders, and others will become osteoclasts, the cells that break bone down. Osteocytes are the most abundant cells in bone tissue. Osteocytes are star-shaped cells that are networked throughout the bone via their long cytoplasmic arms that allow for the exchange of nutrients and other factors from bones to the blood and lymph.

During infancy, childhood, and adolescence, bones are continuously growing and changing shape through two processes called growth ossification and modeling. In fact, in the first year of life, almost percent of the bone tissue in the skeleton is replaced. In the process of modeling, bone tissue is dismantled at one site and built up at a different site.

In adulthood, our bones stop growing and modeling, but continue to go through a process of bone remodeling. In the process of remodeling, bone tissue is degraded and built up at the same location. About 10 percent of bone tissue is remodeled each year in adults. Bones adapt their structure to the forces acting upon them, even in adulthood. This is why exercising, especially when it involves weight-bearing activities, increases bone strength. This is especially true for people over age 40, when natural bone replacement slows down.

Milk, cheese and other dairy products contain calcium. Broccoli, kale, sardines, salmon, Brazil nuts, almonds, oranges and calcium-fortified foods are good sources of calcium as well. The American Academy of Orthopedic Surgeons indicates that getting 1, mg of calcium through diet alone may be difficult and therefore suggests a vitamin supplement as well.

Eat foods with vitamin D to assist in calcium absorption. Adults need 15 mcg of vitamin D a day. Foods with vitamin D include dairy, eggs, fatty fish such as salmon or tuna and fortified orange juice and cereal. Exposure to the sun triggers vitamin D synthesis to produce vitamin D, as well. Perform at least 30 minutes of weight-bearing exercise at least twice a week. Building muscle increases bone density to build healthy bones and prevent osteoporosis.

You don't necessarily need weights or equipment to build muscle. Pushups, squats and planks strengthen muscles over most of the body. As you get stronger, using dumbbells increases the resistance to maintain your strength. Avoid smoking and drinking. Discuss potential side effects of medication with your doctor.

Some medicines can weaken bones and increase your risk of osteoporosis. Your doctor will be able to prescribe bone-boosting medication if needed. Wear your seat belt when driving and a helmet when using a motorcycle.

Why Is the Skeletal System Important?