Anatomy and Physiology of Bone

Received: 03-Jul-2021;Accepted Date: Jul 17, 2021; Published: 24-Jul-2021

Introduction

Bone is a rigid tissue which an important component of the skeletal system. It performs several functions. There are 206 bones in adult body. The bones are of many sizes and shapes. The bone develop after eight week in the foetus, initially they are made of cartilage and later gets matured into the actual bone tissue. The bones in human gets totally developed at the age of 20-25.

Bone consists of three types of tissues. The outer hard tissue known as Compact tissue and the inner spongy tissue known as the Cancellous tissue. The ends of the outer bone, is covered by the special kind of tissue called Subchondrial tissue which protects the bones from the friction. There are about four types of cells in the bone, Osteoblast, Osteoclast, Osteocyte, Haemopoitic cells. Osteoblast is present in the bone, produces the new cells from it. Osteoclast removes the unwanted cells and materials from the bones. Osteocyte maintains the bone as living tissue. Haemopaoietic cells are responsible for the production of white and red blood cells.

The bone primarily comprises of Collagen, and then hydroxyapatite which is the mixture of the calcium and phosphorous. It also comprises of Magnesium, Sodium, Bicarbonate. Water also constitutes the part of weight of bone weight. The Strength of the bone is determined by the Bone Mineral Density, which is given by calculating the mineral density to the volume of the bone.

Bone is typically divided into two parts Diaphysis and Epiphysis. Diaphysis is the region between the ends of the bone, it consists of a hollow region which is known as the Medullary cavity, which is filled with yellow marrow. The extremities of the bone is known as Epiphysis, which is constitutes of the spongy bone, which contains the red marrow. Epiphysis and diaphysis meet at a point called metaphysis which consists of the epiphyseal plate. The epiphyseal plate of the bone contains layer of cartilage which later changes to epiphyseal line at the age of 18-21 years. Medullary cavity consists of inner part called endosteum where bone growth, repairing and remodeling takes place. The outer cavity of the bone consists of blood vessels, lymphatic vessels and nerves and called periosteum.

Bone performs distinct functions in the body. It is necessary for the structural support of the body to move and it is also essential for the movement of the body. It also provides protection to various vulnerable organs like heart, lungs, brain. The synthesis of the essential cells of the body like red blood cells and white blood cells takes place in the bone marrow. Bone provides the nutrient requirement of the body as it consists of many minerals like calcium, magnesium, phosphorous and sodium. It is also defensive in function as it captures lead which is a dangerous mineral as it causes toxicity inside the body.

Thus bone is a very complex structure which performs various functions of the body. It is very essential component of the skeletal system.