Difference Between Bone and Cartilage

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Introduction

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Bones and cartilages are types of connective tissue present in the body. The connective tissues connect and support other body tissues. This type of tissue is made up of loosely packed cells surrounded by the Extracellular Matrix or the ECM. This matrix has living cells that make up the connective tissue. Bones and cartilages are both needed to protect the vital internal organs of the body. They also provide binding and support and help our body organs in movement. It is essential to know the difference between cartilage and bone.


A Cartilage is thin, flexible and resistant to compressive forces. Bones are hard, brittle and lack elasticity. They are highly vascularized and very strong. While cartilages provide cushion-type padding for long bones, bones provide skeletal support. Bones and cartilages differ in their cellular structure, density, types and functions.


We will now have a brief discussion about bone and cartilage and learn to distinguish between bone and cartilage.


What is a Bone?

Bones are living, growing tissue. They build up the skeletal system in the vertebrates. They are made up of collagen, which is a protein. Bones protect the various organs of the body and provide a support framework for the body. They can also produce red and white blood cells and store minerals. They have a complex internal and external structure. 


An adult human body consists of 206 bones. Bones are made up of dense connective tissue and contain special bone cells known as osteoblasts, osteocytes and osteoclasts. Bones have a rich supply of blood through a proper vascular system. They have high compressive strength and can create and replace themselves. Bones also contain an essential mineral called Calcium Phosphate. They can store the calcium and release a part of it into the bloodstream.


The thigh bone or Femur is the longest bone in the human body. The stapes in the human ear is the smallest bone.


What is Cartilage?

Cartilage is a flexible type of connective tissue found in various parts of the body. It is capable of bending but resists stretching. The primary function of cartilage is to connect the bones of a body together. Cartilages are found in the joints between bones like elbows, knees, ankles, rib cage, discs of the spine, ear, nose, throat and bronchioles.


Cartilages keep the joints in motion by cushioning bones against impact. They are not as hard as bones, but they are stiffer and less flexible than normal muscle tissue. There are 3 types of cartilage, namely Fibrocartilage, Hyaline and elastic cartilage.


Cartilages are made up of specialized cells known as chondrocytes. An essential feature of the cartilage is that it has no blood vessels. Due to the lack of blood vessels, cartilage cannot heal itself. It also grows at a slow pace in comparison to other tissues.


Now that we know what bone and cartilage are, we will learn how the two are different in the bone and cartilage difference section.


Let us now differentiate between cartilage and bone. Below is a table listing out the difference between bones and cartilages on the basis of specific parameters.


Difference Between Cartilage and Bone

Parameter 

Bone 

Cartilage

Structure

Rigid, tough and not flexible

Flexible and elastic

Cells

Bones are made up of osteoblasts, osteoclasts and osteocytes.

Cartilages are made up of chondrocytes.

Matrix 

It is both inorganic as well as organic in nature.

It is only organic in nature.

Types

Compact bones and Spongy or cancellous bones

Cartilage can be of 3 types- Hyaline, fibrous and elastic cartilage.

Blood Supply

Bones have a rich supply of blood through a network of blood vessels.

They do not have blood vessels.

Calcium Salts

Bones have rich deposits of calcium salts.

Cartilages may or may not have calcium deposits.

Blood Vessels

Present

Absent

Growth Direction 

Bone growth is bi-directional, i.e. they grow in both directions.

Cartilage growth is unidirectional; i.e. they only grow in a single direction.

Bone Marrow

Present in bones

Absent in cartilages

Haversian System

Present in bones

Absent in cartilages

Volkmann Canals

Present in bones

Absent in cartilages


This cartilage vs. bone comparison will be helpful to distinguish between bone and cartilage. Both bones and cartilage are types of connective tissue but have a different structure, nature and functions in the body.

FAQ (Frequently Asked Questions)

Q1. Can a Cartilage Repair Itself?

Cartilage is an essential tissue in the body. However, it does have a drawback. Unlike other tissues, it does not have the capability to heal itself. This is because the cartilage does not contain nerves or blood vessels. It gets its supply of nutrients through the perichondrium. The cartilage cells or the chondrocytes cannot replicate or repair themselves. The cells in the cartilage divide slowly. Their growth rate is very low. So, the cartilage cannot heal or repair itself because of its limited blood supply.


Thus, a damaged or injured cartilage cannot heal, and the medical intervention will be required for its repair.

Q2. What is the Haversian System?

The Haversian system is also known as the Osteon. They are cylindrical structures present in bones. These series of tubes are called Haversian canals and are present around narrow channels formed by lamellae. They are present in the bones of all animals and humans.  They surround blood vessels and nerve fibres that are spread throughout the bone. They also communicate with bone cells or osteocytes. The canals and the surrounding lamellae together form a Haversian system.


These canals are typically arranged along the long axis of the bone. They provide the essential oxygen and nutrients to the bones. This system is not present in cartilages.

Q3. What are the Volkmann Canals?

Volkmann's canals are unique tube structures present in the bone tissue. They are a characteristic feature of the bones in all animals. These are microscopic structures found in compact bones. These canals carry small arteries throughout the bone. They are also known as perforating holes. These channels are present inside the osteons of the Haversian canals.


They interconnect the Haversian canals with the periosteum and also with each other. Volkmann's canals transmit blood vessels from the periosteum into the bone. They are the chief provider of oxygen, energy and nutrients for osteons. These canals are part of the bone vascular system. They are not present in cartilage due to which the cartilage does not have a blood supply.