Welcome to softilmu, a science blog that shares with sincerity. This time we will discuss about Bone, some of the main points in this post are Definition of Bones, Bone Function, Bone Structure, Bone Parts, Kinds of Bones, and The process of bone formation. Hopefully it can be useful.
Bone is a connective tissue composed of cells, fibers, and an extracellular matrix. The bone matrix is ​​the hardest part located in the outer layer of the bone, which is caused by the deposition of minerals in the matrix, so that the bone undergoes calcification.
There is also cartilage in the human body.cartilage), namely connective tissue that has the ability to stretch, forms a strong support for soft tissue, provides flexibility, and is highly resistant to pressure.
For example, the bone in a chicken thigh, at both ends is cartilage, while the part that lies between the two or the hardest part is called bone.
Bones serve as a rigid body framework, and provide attachment sites for muscles and organs found in a person’s body. Bones also protect the brain, which is located in the skull, you can imagine when an accident hits a person’s head if without the skull bone, the important organs in it such as the brain and all the nervous system are easily destroyed.
Bones protect the heart and lungs in the chest cavity, and the sexual organs and urinary tract are protected by bones called bones pelvis. In addition, bones also function in hemopoiesis (formation of blood cells), and as reservoir (storage) calcium, phosphate, and many other minerals.
Almost all of the calcium (99%) in the body is stored in the bones, and when the body needs calcium, it will come from the bones.
While cartilage functions as a shock absorber (pressure reducer). Which is when someone lands after jumping, the body will receive great pressure, this is where one of the functions of cartilage plays a role, namely reducing the existing pressure. This cartilage is avascular or not connected to blood vessels.
Human bones
BONE STRUCTURE

Bone has a matrix where the matrix is ​​a hard structure in bone, the matrix has many blood vessels, because this hard structure is difficult to be penetrated by nutrients and metabolites. The bone matrix is ​​made up of strong protein fibers, mainly collagen. This matrix is ​​produced by osteoblasts. Osteoblasts is a cell found in bone that also functions to make new bone cells and absorb minerals from the blood. The matrix has organic and inorganic components. Organic components allow bones to withstand stress, while inorganic components or mineral components withstand stress.

Other cells found in bone are cells osteoclastThese cells have the opposite function of osteoblasts, namely their function is to destroy bone by dissolving minerals in the blood. Cells also found in bone are osteocytes, these cells maintain the balance of minerals in the blood, they direct the absorption of minerals from the blood and direct the return of minerals into the blood, so that the bones and the body both get enough minerals. The analogy is that osteocytes are ordered, then osteoblasts and osteoclasts work.
The main organic component of the bone matrix is ​​type I collagen fibers, which contain proteins, one of which is glycoprotein osteocalcin and osteopontin, which binds tightly to calcium during bone mineralization. Other matrix proteins are sialoprotein, which binds osteoblast in the extracellular matrix.
The inorganic component of the matrix consists of calcium and phosphate in the form of hydroxyapatite crystals. The bonding of collagen fibers with hydroxyapatite crystals will cause bones to become hard, durable, and strong. This mineral component will be maintained in the blood with the help of parathyroid hormone (from the gland next to the thyroid) and calcitonin (from the thyroid gland).
Bone marrow is a soft connective tissue found in spongy bone, its function is to produce blood cells. There is also a periosteum in bone, this periosteum is the strong part, which consists of a fibrous membrane that covers and protects the outer surface of the bone.
Bone Parts
BONE PARTS

D. KINDS OF BONE

Bone is composed of collagen fibers called osseous lamellae, which are lined up at the edges of the bone, surrounding the blood vessels. Examples of compact bones are long bones (such as thigh bones, feet, hands).

2. Spongiosa/cancellous bone
Examples of this bone is the inside of compact bone, such as the bone marrow cavity, in infants this cavity looks red and produces lots of blood cells, in adults, the bone marrow cavity looks yellow and filled with fat cells. This spongy bone will also appear when we bite the bone at the end of the cartilage in chicken, this bone is in the form of a sponge (pores).
Cartilage is a bone that has flexible properties and does not have blood vessels or nerves except for the outermost layer (perichondrium). There are three types of cartilage, namely:
This bone is the most abundant in the body, serving as the skeletal model for most bones. In adults, these bones are found on the joint surfaces of bones, the tips of the ribs, nose, larynx, trachea, and bronchi (breathing tubes).
Contains elastic fibers that branch in the matrix and are very flexible, found in the outer ear, auditory tube (the tube that connects the nose to the ear), epiglottis (covers the respiratory tract when we swallow, so food does not enter the respiratory tract), and the larynx.

c. Fibrocartilage

This cartilage provides tensile strength, withstands loads, and is quite strong against stress. Found in the intervertebral discs (connective tissue located between each vertebral column), in the elderly, the intervertebral discs, which are 80% composed of water, begin to lack elasticity due to the reduced amount of water, so that in the elderly it is easy for disorders such as pain in the neck to occur. spine, and bent habitat.
Another example is the pubic symphysis (cartilage located above the pubic), this bone protects the urinary and sexual organs from the pressure and impact that occurs.
E. THE PROCESS OF BONE FORMING
Bone Formation Process
THE PROCESS OF BONE FORMING

Bone is formed through a process known as ossification.

Growth in the embryo goes through two processes, namely endochondral ossification and intramembranous ossification.
This endochondral ossification occurs when hyaline cartilage undergoes calcification, mesenchymal cells in the periosteum (the outermost layer of bone) turn into osteoprogenitor cells and form osteoblasts (bone-forming cells). Osteoblasts produce a matrix, which undergoes calcification. The bones began to elongate starting from the diaphysis nya (long bones), then followed by epiphysis (end joint surface). And finally the cartilage had become hard bone.
In intramembranous ossification, cartilage growth is not preceded by cartilage, but from connective tissue mesenchyme. These mesenchymal cells turn into osteoblasts which then produce matrix as well, and then undergo calcification. Many ossification centers are formed, connect with each other and form a spongy bone network, which consists of thin spines or so-called spines. trabeculae. The maxilla, mandible (jaw), clavicle, and most of the flattened bones of the skull are formed by intramembranous ossification.

So that’s our discussion about Bone. Hopefully the knowledge can be useful. If there is something you don’t understand, please ask friends via the comment box. Thank you for visiting, and don’t forget to continue to follow Softilmu.

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