1. The Skeletal System

The skeletal system is the bones in our body and the tissues such as the tendons, ligaments, and cartilage that connect them. The role of our skeletal system is to support our body. Without the support of the skeletal system our body would be like a puddle of skin and guts in the floor. Not only does it support our body but it protects our internal organs and other fragile tissues. It protects the brain, eyes, heart, lungs and spinal cord. Our brain is protected by the cranium known as our skull. It also protects our eyes. The ribs protect our heart and our lungs and our spine protects the spinal cord. The skeletal system provides us with both support and protection. The bones are what provide the structure for our muscles to move, the tendons are the tough inelastic bands that hold muscles to the bones. A typical bone has an outer layer of hard, compact bone that is very strong and tough. Inside there is a layer or spongy bone which is slightly flexible. In the middle of some bones there is jelly-like bone marrow. The bone marrow is where new cells are constantly being produced for our blood. Our bones need important mineral called calcium to keep them strong. Another way for our bones to stay healthy is to exercise regularly and eating dairy products that contain calcium. A disease associated with the skeletal system is one called Osteoporosis which is particular among the elderly, resulting in loss of bone tissue. The bone loses calcium, becomes thinner, and eventually it can disappear completely. Another one is Arthritis which is an inflammatory disease that damages joints and its surrounding structure.

a. Axial skeleton: The axial skeleton consists of the bones of the skull, the vertebral column, and the rib cage. It is structural support for the body, the attachment points for the ligaments and muscles and protects the brain, spinal cord and major organs of the chest.

b. Appendicular skeleton: The appendicular skeleton is the portion of the skeleton that includes the limbs, the pelvis, and the pectoral girdle. The primary function of the appendicular skeleton is locomotion and support. The appendicular also makes up the arms and legs.

c. Spongy bone: The spongy bone is calcium that makes the inside of the bone. It is lighter, softer, and weaker than compact or cortical bone. It is found on the inside of some bones surrounded by the stronger, and more protective compact bone. It usually contains red bone marrow.

d. Compact bone: also called the cortical bone, is dense bone in which the bony matrix is solidly filled with organic ground and inorganic salts, leaving tiny spaces that contain bone cells. Has sponge-like appearance with numerous spaces and is found in the marrow space of a bone.

e. Marrow: marrow is a soft fatty substance in the cavities of bones, in which white blood cells are produced; in large bones it produces new blood cells. There are two types. Red and yellow bone marrow.

f. Osteoblasts: Are cells that originate in the bone marrow and contribute to the production of new bone. These cells build up the matrix of the bone and play a role mineralization of the bone matrix.

g. Ligaments: Ligaments are stretchy bands of tissue that hold one bone to another. Ligaments allow the joints to move, control their range of motions, and stabilize them so that the bones move in proper alignment.

h. Tendons: Also called sineviews, connect muscle to bone. Without the connection between the muscles and bones that responsible for controlling movements like walking, running, and jumping, it would be impossible for our body to move the way it does. It is important to keep them strong and healthy.

i. Ball-and-socket joint: a joint in which the rounded surface of a bone moves within a depression on another bone, allowing the joint to be free of movement of any other kind of joint. It provides swing for the arms and legs in various directions.

j. Hinge joint: Is found in