Analysis Of Contents Of Cow And Goat Bone Ash

1.2.2 MOLECULAR STRUCTURE

i. Matrix: The majority of bone is made of the bone matrix. It is composed primarily of inorganic Hydroxyapatite (Ca10(PO4)6(OH)2) and organic collagen. Bone is formed by the hardening of this matrix around entrapped cells. When these cells become entrapped from osteoblasts they become osteocytes.

ii. Inorganic: The inorganic is mainly crystalline mineral salts and calcium, which is present in the form hydroxyapatite. The matrix is initially laid down as unmineralized osteoid (manufactured by osteoblasts). Mineralization involves osteoblasts secreting vesicles containing alkaline phosphate. This cleaves the phosphate groups and acts as the foci for calcium and phosphate deposition. The vesicles the rupture and act as a center for crystals grow on. 

iii. Organic: The organic part of matrix is mainly composed of Type I collagen. This is synthesized intracellularly as tropocollagen and then exported, forming fibrils. The organic part is also composed of various growth factors, the functions of which are not fully known. Factor present include Glucosaminoglycans. Osteonectin, Osteocalcin, bone sialo protein, Osteopontin and cell attachment factor. One of the main things that distinguishes the matrix of a bone from that of another cell is that the matrix in bone is hard.

iv. Woven and Lamella: Two types of bone can be identified microscopically according to the pattern of collagen forming the osteoid (collagenous support tissue of Type I collagen embedded in Glycosaminoglycan gel).

a. Woven bone, which is characterized by haphazard organization of collagen fibers and is mechanically weak.

b. Lamellar bone which has a regular parallel alignment of collagen into sheets (Lamellae) and is mechanically strong.

Woven bone is produed when osteoblasts produce osteoid rapidly which occurs initially in all fetal bones (but is later replaced by more resilent lamellar bone). In adult woven bone is created after fractures or in paget’s disease. Woven bone is weaker, with a smaller number of randomly oriented collagen fibers, but forms quickly; it is this appearance of the fibrous matrix that the bone is termed woven. It is soon replaced by lamellar bones, which is highly organized in concentric sheets with a much lower proportion of osteocytes to surrounding tissue. Lamellar bone, which makes it first appearance in the fetus during the third trimester, is stronger and filled with many collagen fibers parallel to other fibers in the same layer (these parallel columns are called osteons). In cross-section the fibers run in opposite direction in alternating layers, much like in plywood, assisting the bone’s ability to resist torsion forces. After a fracture, woven bone forms initially and is gradually replaced by lamellar bone during a process known as “bony substitution”. Compared to woven bone, lamella bone formation takes more slowly. The orderly deposition of collagen fibers restricts the formation of osteoid to about 1 to 2 micro meter per day. Lamellar bone also requires a relatively flat surface to lay the collagen fibers in parallel or concentric layers. These terms are histogic, in that a microscope is necessary to differentiate between the two types

1.3 CHARACTERISTIC OF BONE

The primary tissue of bone, osseous tissue, is a relatively hard and has light weight composite material formed mostly of calcium phosphate in the chemical arrangement termed Calcium Hydroxyapatite (Ca10(PO4)(OH)2) (this is the osseous tissue that gives bone their rigidity).

It has relatively high compressive strength but poor tensile strength of 104-121 Mpa meaning it resists pushing force well, but not pulling forces. While bone is essentially brittle, it does have a significant degree of elasticity, contributed chiefly by collagen. All bones consist of living and dead cells embedded in the mineralized organic matrix that make up osseous tissue.

1.4 TYPES OF BONE

There are five types of bones in the human body:

Long bone, short bone, flat bone, irregular bone and sesamoid bone.

i. Long bones: They are characterized by a shaft, the diaphysis that is much longer in length than width. They are comprised mostly of compact bone with lesser amounts of marrow, which is located within the medullary cavity and spongy bone. Most bones of the limbs including those of the fingers and the toes are long bones. The exceptions are those of the wrist, ankle and kneecap.

ii. Short bone: are roughly cube shaped, and have only a thin layer of compact bone surrounding a spongy interior. The bones of the wrist and ankle are short bones as are the sesamoid bones.

iii. Flat bones: are thin and generally curved, with two parallel layers of compact bones sandwiching a layer of spongy bone. Most of the bones of the skull are flat bones, as is the sternum.

Sesamoid bones: Are bones embedded in tendons. Since they act to hold the tendon further away from the joint, the angle of the tendon is increased and thus the leverage of the muscle is increased. Examples of sesamoid bones are the patella and the pisiform. 

iv. Irregular bones: do not fit into the above categories. They consist of thin layers of compact bone surrounding a spongy interior. As implied by the name, their shapes are irregular and complicated. Often this irregular shape is due to their many centers of ossification or because they contain bony sinuses. The bones of the spine, hips and some bones of the skull are irregular bones. Example include the ethmoid and sphenoid bones.

1.5 FUNCTIONS OF BONE

Bones have eleven main functions:

A. MECHANICAL FUNCTIONS OF BONE

i. Protection: Bones can serve to protect internal organs, such as the skull protecting the brain or the ribs protecting the heart and lungs.

ii. Movement: Bones, skeletal muscles, tendons, ligament and joint function together to generate and transfer forces so that individual body parts or the whole body can be manipulated in three dimensional space. The interaction between bone and muscle is studied in Biomechanics.

iii. Shape: Bones provides a frame to keep the body supported.

iv. Sound transduction: Bones are important in the mechanical aspect of overshadowed hearing.

B. SYNTHETIC FUNCTION OF BONE

v. Blood production: The marrow, located within the medullary cavity of long bones are interstice of cancellous bones, produces blood cells in process called “Haematopoiesis”

C. METABOLIC FUNCTION OF BONE

vi. Mineral Storage: Bones act as reserves of minerals important for the body, most notably calcium, phosphorus etc.

vii. Growth Factors Storage: Mineralized bone matrix stores important growth factors such as insulin-like growth factor, transforming growth factor, bone morphogenetic proteins and others.

viii. Fat storage: The yellow bone marrow acts as a storage reserve of fatty acids

ix. Acid-Base balance: Bones buffers the blood against excessive pH changes by absorbing or releasing alkaline salts.

x. Detoxification: Bone tissues can also store heavy metals and other foreign element, removing them from the blood and reducing their effects on other tissues. These can later be gradually release for excretion.

xi. Endocrine organs: Bone controls phosphate metabolism by releasing fibroblast growth factors -23 (FGF-23) which acts on kidneys to reduce phosphate reabsorption. Bone cells also release a hormone called osteocalcin which contribute to the regulation of blood sugar (glucose) and fast deposition. Osteocalcin increases both the insulin secretion and sensitivity, in addition to boosting the number insulin-producing cells and reducing stores of fat.

1.6 USES OF BONE 

Bones from slaughtered animals  have  a  number  of  uses. They have been used as crafting  materials,  for  buttons,  handles,  ornaments etc. A special genre is scrimshaw. Ground bones are used as an organic phosphorus- nitrogen fertilizer and as additive in animal  feed. Bones, in  particular  after  calcinations  to bone ash  is  used as source of calcium phosphate for the production  of bone china and  previously  also  phosphorus chemicals.