Bio40A Ch06 Notes Part 1 PDF

Bone Tissue part 1 I. INTRODUCTION A. Bone is made up of several different tissues working together: bone, cartilage, dense connective tissue, epithelium, blood forming tissues, adipose, and nervous tissue. B. Each individual bone is an organ; the bones, along with their cartil...

Bone Tissue part 1 I. INTRODUCTION A. Bone is made up of several different tissues working together: bone, cartilage, dense connective tissue, epithelium, blood forming tissues, adipose, and nervous tissue. B. Each individual bone is an organ; the bones, along with their cartilages, make up the skeletal system. II. FUNCTIONS OF THE SKELETAL SYSTEM A. Bones support the soft tissues and provide attachment sites for muscles, thereby serving as the structural framework for the body. B. Many of the body’s internal organs are physically protected by bony coverings. C. Bones assist skeletal muscles to produce movement of body parts. D. Bones store and release several minerals, especially calcium and phosphorus, to help maintain mineral homeostasis. E. Hemopoiesis, blood cell formation, occurs in the red marrow of bones. F. Yellow marrow of adult bones serves as a site of triglyceride storage. III. STURCTURE OF BONE A. The structure of bone can be analyzed by studying a long bone. B. A typical long bone consists of numerous parts. 1. The diaphysis is the shaft of the long bone. 2. The epiphyses are the ends of the bone that articulate with adjacent bones. 3. The metaphyses are the areas between the epiphysis and diaphysis. It includes the epiphyseal plate, the site of bone elongation in growing bones. 4. Hyaline cartilage (articular cartilage) at the ends of the bones reduces friction and absorbs shock at freely moveable joints.  5. The periosteum is a connective tissue covering of the surface of the bone which contains osteogenic cells which promote bone growth in width, assists in fracture repair, helps nourish bone tissue, and serves as an attachment point for ligaments and tendons. 6. The space within the diaphysis is the marrow cavity which contains yellow marrow (adipose connective tissue). 7. The endosteum is the lining of the medullary cavity. IV. HISTOLOGY OF BONE TISSUE A. Bone (osseous) tissue consists of widely separated cells surrounded by large amounts of matrix. B. There are four principal types of bone cells. 1. Osteogenic cells undergo cell division and develop into osteoblasts. 2. Osteoblasts are bone-building cells, promoting bone deposition. 3. Osteocytes are mature bone cells, derived from osteoblasts, that maintain bone tissue. 4. Osteoclasts are derived from monocytes and serve to break down, or resorb, bone tissue. C. The matrix of bone contains inorganic salts, primarily hydroxyapatite and some calcium carbonate, and collagen fibers. 1. These and a few other salts are deposited in a framework of collagen fibers, a process called calcification or mineralization. 2. Mineral salts confer hardness on bone while collagen fibers give bone its great tensile strength. 3. The process of calcification occurs only in the presence of collagen fibers.