The Skeletal System is composed of bones and bone tissue. The skeletal system has four main components, bones, tendons, cartilage and ligaments. The major functions of the skeletal system are support, protection, movement and storage. In supporting the body, the bones are used for bearing the weight of the body and is the major supporting tissue of the body. In protecting the body, bone protects the organs it surrounds. Skeletal muscle provides the body with movement in that it attaches muscle to bone by tendons. The contractions of skeletal muscles allows the bones to move therefore producing movements within the body. When providing storage, the skeletal system stores minerals within blood that are then taken into the bones. The essential minerals that are stored in bones are calcium and phosphorus. Both calcium and phosphorus are essential for many physiological processes within the body.
There are three types of cartilage involved in bone, hyaline cartilafge, fibrocartilage and elastic cartilage. Hyaline cartilage is the type of cartilage that is mostly associated with bone because it is the main cartilage that provides the skeletal system with the ability to help lengthen and strengthen the bones. Hyaline cartilage consists of specialized cells called chondroblasts(meaning the beginning ) that produces a matrix surrounding themselves. When matrix surrounds a chondroblast, it becomes a chondrocyte (a cell) that occupies a space called a lacuna.
The histology of bones begins with the bone matrix and the bone cells. Bone consists of extracellular bone matrix and bone cells. The bone cells produce the bone matrix, become entrapped within it and break it down so that the new matrix can replace the old matrix. The composition of the bone matrix is responsible for the characteristics of bone. The bone matrix is is thirty five percent organic and sixty five percent inorganic material. The organic material consists primarily of collagen and proteoglycans and the inorganic material consists of a calcium phosphate crystal called hydroxyapatite. Bones are composed of three types of cells osteoblasts, osteocytes and osteoclasts. Osteoblasts are the bone forming cells that release matrix vesicles, osteocytes are the cells of bone and osteoclasts are responsible for the reabsorption or breakdown of bone.There are four types of bone classifications, woven bone, lamellar bone, spongy bone and compact bone. Woven bone the collagen fibers randomly oriented in many directionsand lamellar bone is the mature bone that dervies from woven bone that is organized into thin sheets or layers with the collagen fibers being parallel to one another. Spongy bone is composed of interconnecting rods or plates of bone called trabeculae and compact bone is denser and has fewer spaces than spongy bone. Compact bone contains blood vessels and loose connective tissue.
In understanding chapter six, I was able to grasp that without the skeletal system is the most important component within the body and that without the body would be unable to move and provides its essential full function of the body. Without calcium and phosphorus contained in the bones, the bones will not grow and will therefore result in the absence of bone growth and bone disease.
The questions that I developed based on my reading of chapter six were:
(1) How would bones function without all of the four types of bone working together (Woven, Lamellar, Spongy and Compact Bone)
(2) If calcium and phosphorus were absent from the bones, would the bones be able to function at their full potential?
(3)What role does fibrocartilage and elastic cartilage provide in the skelatal system?
(4) Where does the matrix vesicles lie within the bone?
(5) Why do all bones not contain sinus cavities?
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