Structure of Bones
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| What’s is Structure Of Bones |
The bones in your body are made up of an extraordinarily complex connective tissue that’s structure matches its function. It is comprised of cells, fibers and extracellular material or matrix.
The bones in your body have 3 major types of bone cells.
Let’s start by looking at a diagram of bone tissue. There are 2 main types of bone tissue, compact bone and cancellous bone or spongy bone. Compact bone surrounds the spongy bone tissue and it has a unique appearance. These cylinder shaped structures are called osteons or Haversian systems. In the middle of these osteons is a central Haversian canal that runs lengthwise through the bone and it houses nerves and blood vessels that supply the bone.
The cylinder shaped layers of the osteons are called concentric lamellae. The lamellae are composed of calcified matrix. The matrix of the bones in your body is composed of inorganic salts and organic material. The inorganic matrix is made up of rocklike crystals of calcium and phosphate called hydroxyapatite crystals, calcium carbonate and magnesium, sodium, sulfate and fluoride are also found in bone material.
The organic material is comprised of collagenous fibers and a gel like ground substance containing protein and polysaccharides. The ground substance is important in providing support and adhesion between cellular and fibrous elements.
There is also circumferential lamellae that runs along the periosteum, which covers the outside of bones, and along the endosteum which lines the inner spongy bone tissue. Interstitial lamellae are located between osteons.
Lacunae are the small spaces in bone tissue where mature bone cells called osteocytes are imprisoned. These cells are responsible for maintaining the bone matrix.
Canaliculi are small canals that extend in many directions from the lacunae connecting to other lacunae and the central canal. They provide for intercellular communication and passageway for the delivery of nutrients to the osteocyte cells.
There are also transverse canals which connect central canals to one another and these canals also house nerves and blood vessels.
Now for spongy bone tissue. Spongy bone has no osteons as it has a lattice like appearance of crisscrossing branches called trabeculae. The trabeculae are comprised of endosteum surrounding parallel lamellae composed of bone matrix, and osteocytes in lacunae with canaliculi extending out from the lacunae.
Some of the canaliculi open onto the surface of the trabeculae. Like in compact bone tissue, the canaliculi provide a passageway for nutrients to reach the osteocyte cells.
The formation or lattice like look of spongy bone allows it to distribute any stress or pressure applied to it throughout the entire framework.
Functions of Bones
Bones have many functions in the body, in this video we are going to cover the 5 major functions of bones.
Support of the body. Many tissues and organs attach to bones, as do tendons from muscles, so bones provide a rigid framework for the body. This skeletal framework provides the strength to support the body.
Bones provide levers for body movement. Movement is done through muscle contraction, and muscles are attached to bones by tendons. So, a muscle contraction moves a bone, which moves the body part where the bone is located.
Bones provide protection. The brain is protected by the skull, or the bones of the cranium, and the heart is protected by the ribs.
Bones house red bone marrow. Red bone marrow produces red blood cells, which carry oxygen to all parts of the body and remove carbon dioxide, white blood cells, which protect the body from disease and foreign invaders and platelets, which help to prevent bleeding.
Bones are a storage reservoir for calcium and phosphorus. Calcium is important in muscle contraction and in clotting of blood. Having a proper level of calcium in the blood stream is vital for life. When you don’t consume enough calcium from food, it can be taken from bones to increase the amount in the bloodstream. And when you consume more calcium than your body needs, it can be deposited into the bones for later use.
Types of Bones
There are 4 major classifications of bones based on their shapes. Long bones, short bones, flat bones and irregular bones.
Not every single bone in the body fits perfectly into one of these classifications, as some bones may have characteristics of 2 or more of the classifications.
Long bones are longer than they are wide, and they are mainly located in the appendicular skeleton, or in the arms and legs. At each end of a long bone a joint is formed. Long bones are important in movement and they support the weight of the body. Some examples of long bones are the femur or thigh bone, the humerus or arm bone, and the phalanges, or the bones of the fingers.
Short bones are usually as long as they are wide, and they are often described as being cube shaped. Examples of short bones are the carpals of the wrist and the tarsal bones located in the ankle region. Short bones have little to no movement and they provide support and stability.
Flat bones are usually thin and sometimes have a curved shape to them. Flat bones protect internal organs such as the brain and heart, and many of them have broad surfaces for the attachment of muscles. Some examples of short bones are the cranial bones in the skull, the sternum and the ribs.
Irregular bones vary in shape so they do not fit into one of the 3 previous categories. Some irregular bones protect organs and some such as the patella or knee cap attach to tendons. The patella are also classified as sesamoid bones, or round bones. Some sources list sesamoid bones as an irregular bone, and some sources list sesamoid bones as a fifth bone classification.
And that be the basics on the types of bones in the body.
