Human beings are vertebrates, meaning that we have a spinal column or backbone. In addition to that backbone, we also have an extensive skeletal system that’s made up of bones and cartilage as well as tendons and ligaments.
Bone is the substance that forms the skeleton of the body. It is composed chiefly of calcium phosphate and calcium carbonate. There are 206 bones in the adult human body.
Functions of bones
Support
Bone provides a rigid framework as well as support for other parts of your body.
For example, the larger bones of the legs offer support to your upper body while you’re standing up. Without our bones, we’d have no defined shape.
Movement
Bones also play an important role in the movement of your body, transmitting the force of muscle contractions. Your muscles attach to your bones via tendons. When your muscles contract, your bones act as a lever while your joints form a pivot point. The interaction of bones and muscles contributes to the wide range of movements your body is capable of making.
Protection
Your bones also protect many of your internal organs. Good examples of this include the way your rib cage surrounds organs such as your heart and lungs or how the bones of your skull surround your brain.
Blood cell generation and maintenance
The many cells of your blood — red blood cells, white blood cells, and platelets — are formed within your bones. This process is called hematopoiesis, and it occurs in a part of your bone marrow called the red marrow.
Storage
Important minerals, such as calcium and phosphorus, are stored within your bones. When your body needs more of these resources, they can be released back into your bloodstream for use.
In addition to red marrow, bones also contain another type of marrow called yellow marrow. This is where some fat tissue is stored. The fats in this tissue can be broken down and used for energy if required.
Types of bone
The bones of your body are divided into five different types based on their shape and function.
1. Long bones
As their name implies, long bones are longer than they are wide.
Eg :
The femur (thigh bone)
Humerus (upper arm bone)
Bones of your fingers and toes
The function of long bones is centered on supporting the weight of your body as well as facilitating the movement of your body.
2. Short bones
Short bones have very equal proportions and are roughly shaped like a cube.
Eg :
Bones of wrists
Bones of ankles.
Short bones provide stability to the wrist and ankle joints and also help facilitate some movements.
3. Flat bones
Flat bones aren’t actually flat, but thin and slightly curved.
Eg :
Cranial bones
Scapula (shoulder bone)
Ribs
Flat bones often serve to protect your internal organs. Think of how your cranial bones tightly surround your brain.
Flat bones can also serve as points of attachment for your muscles. Your shoulder bone is a good example of this.
4. Irregular bones
The irregular bones of your body have varied shapes that are often complex.
Eg :
Vertebrae
Pelvic bones
The many bones of your face
Like flat bones, the function of irregular bones is to protect various parts of your body. For example, your vertebrae protect your spinal cord.
5.Sesamoid bones
Sesamoid bones are small and round in shape. They’re found throughout the body, mostly in the hands, feet, and knees.
Interestingly, their placement can vary from person to person.
Eg :
The patella (kneecap - The prominent sesamoid bone in the body)
Sesamoids are bones that form within a tendon and bones surrounded by tendons, which connect muscle to bone. They help to protect the tendons from wear and tear and to relieve pressure when a joint is used. They give a mechanical advantage to the muscles and tendons in which they are located.
Types of bone tissue
Your bones are composed of two different types of tissue.
Compact
The compact bone is the outer shell of the bone. It’s made up of many closely packed layers of bone tissue.
Compact bone contains a central canal that runs the length of the bone, often called a Haversian canal. Haversian canals allow blood vessels and some nerves to reach into the bone.
Spongy
Spongy bone isn’t as dense as compact bone and looks very much like a honeycomb. It contains cavities that hold the red or yellow bone marrow.
Spongy bone is also important for movement. If all of your bone tissue was compact, you’d probably be too heavy to move! Spongy bone also helps to absorb shock and stress from movement.
Types of bone cells
There are a variety of different cells present in your bones.
Mesenchymal stem cells
These are stem cells found in your bones. They can develop into a variety of different cell types, including osteoblasts.
Osteoblasts
These cells originate from mesenchymal stem cells. They work to deposit collagen and minerals that will eventually form mature bone.
When they’ve accomplished this, osteoblasts can become a cell on the bone surface, develop into an osteocyte, or die by a natural process called apoptosis.
Osteocytes
Osteocytes are trapped within the bone tissue and are the most prevalent cell type in mature bone tissue. They monitor things such as stress, bone mass, and nutrient content.
They’re also important for signaling during bone remodeling, the process of bone resorption, and the generation of new bone tissue that can follow.
Osteoclasts
Osteoclasts are large cells. They secrete a variety of ions and enzymes that allow bone tissue to be resorbed. The material that has been resorbed can then be used to create new bone tissue.
Your bones are classified according to their size and function. On the inside, bones contain a variety of different tissues and cells. All of these components work together to make your bones the multifunctional tissue that they are.
How to improve bone health?
✔Eating foods rich in calcium and vitamin D
✔Doing the needed exercises for your body
✔ Having good health habits
are some of the ways that help keep our bones healthy.
But if we don't eat right and don't get enough of the right kinds of exercise, our bones can become weak and even break.
Prasadini Dikwella
https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/bones
https://www.healthline.com/health/bone-health/bone-function
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