Bone vs Cartilage: Difference and Comparison

Connective tissue is one of the four basic types of tissue in our body that provide support, cohesion, protection and connection between all other tissues of the body.

Bones and cartilage and types of specialized connective tissue that give support to the body protect the body and provide a framework for the body’s various organs and tissues.

Key Takeaways

1. Bones are rigid structures composed of calcium and phosphate, supporting and protecting vital organs.
2. Cartilage is a flexible connective tissue composed of chondrocytes and collagen, acting as a cushion between joints.
3. Both are essential components of the skeletal system, each with unique functions and properties.

Bone vs Cartilage

Bone forms part of the vertebral skeleton. It is hard, inelastic, highly vascularized and a tough, strong organ. Cartilage is a connective tissue that protects the bone from rubbing against each other. It is soft, elastic, thin, avascular, flexible and resistant to compressive forces.

Bones are rigid, strong, non-flexible supportive connective tissues made up of bone cells called osteoblasts, osteoclasts, and osteocytes, enclosed in a calcified extracellular matrix(ECM).

The major mineral in the ECM of bones is calcium and phosphorus that, on maturation, form hydroxyapatite crystals with the chemical formula Ca10(PO4)6(OH)2.

Cartilages are semi-rigid, flexible, supportive connective tissues made of specialized tissues called chondrocytes that produce their extracellular matrix composed of organic collagenous proteins—a ground substance made up of fibres and chondroitin sulphate and proteoglycan.

The collagen and elastin fibres provide the cartilage with its elastic and compressible nature.

Comparison Table

Parameters of Comparison	Bone	Cartilage
Nature	Strong, rigid, non-flexible tissue	Semi-rigid, flexible, compressible tissue.
Types of cell	Made up of there are types of cells called: 1.Osteoblasts 2.Osteoclasts 3.Osteocytes	Made up of cells called chondrocytes.
Extra-cellular Matrix	Made up of both organic and inorganic materials. Organic materials include collagen and fibres. Inorganic materials include calcium and phosphate minerals.	Made up of organic materials including collagen, proteoglycans, elastin fibres, and glycosaminoglycan.
Calcification	Made up of both organic and inorganic materials. Organic materials include collagen and fibres. Inorganic materials include calcium and phosphate minerals.	No calcification present, except in calcified cartilage.
Compressibility	Not compressible. It is brittle.	It is compressible and hence is found in bone joints.
Elasticity	Not elastic in nature.	Elastic in nature.
Vascular System	Bones are supplied by a rich network of blood vessels.	Cartilage is an avascular tissue.
Canal System	In bones, Haversian and Volkmann canal systems are found.	In cartilages, both Haversian and Volkmann canals are absent
Growth	Growth in bones takes place in both directions.	Growth in cartilages takes place only in one direction.
Types of growth	Growth in bones can be 1.Endochondral. 2.Intramembranous.	Growth in cartilage can be: 1.Interstitial. 2.Appositional.
Types	Types of bones are: 1.Compact bone 2.Spongy bone	Types of cartilage are: 1.Hyaline 2.Fibrocartilage 3.Elastic cartilage.

What is Bone?

Bones are a type of specialized connective tissue made up of two components: bone cells and an extracellular matrix. Bone cells are called osteoblasts, osteoclasts, and osteocytes. These cells arise from osteoprogenitor cells.

The extracellular matrix of bones is made up of organic and inorganic materials, the most important I then being calcium phosphate crystals called calcium hydroxyapatite.

The microstructure of bones shows that each bone cell lies in spades called lacunae which are arranged in closely packed systems called osteons. Osteons are richly supplied by blood and lymph vessels through the specialized canals called Haversian and Volkmann canals.

Calcification of cartilage from bones. Bones are mainly of two types :

1. Compact Bone: Osteons are closely packed in the extra-cellular matrix.

2. Spongy Bone: Osteons are loosely scattered in the extra-cellular matrix.

The main functions of bone are providing a supportive framework to the body, protecting internal organs, giving shape to the body and helping in body movement. For example, the humerus, skull bones, radius, pelvic girdle etc.

What is Cartilage?

Cartilages are a type of specialized connective tissue made up of cartilage cells called chondrocytes and chondrocytes. Chondrocytes secrete their matrix.

The matrix consists of organic materials only consisting of collagen fibres, proteoglycans, and elastin fibres that provide elasticity to this tissue.

The microstructure of cartilage shows that it lacks canal systems and any vascular supply. It derives nutrition from surrounding cell matrices.

Some cartilage may be calcified. Some of the best examples of cartilage are nose and ear cartilage which is movable and bendable. Cartilages are also present in the bone joint, allowing smooth movement and shock absorbance.

Main Differences Between Bone and Cartilage

1. The primary difference between bones and cartilage lies in their rigidity and elasticity. Bones are rigid and brittle in nature, while cartilages are elastic and compressible.
2. The extracellular matrix of bone suffers from cartilage. Bones have both inorganic and organic materials in their extracellular matrix, while cartilages have only organic materials.
3. Bone cells differ from cartilage cells both in structure and function. Bone cells are called osteoblasts and osteocytes, while cartilage cells are called chondrocytes. The primary function of bone cells is calcification, while that of cartilage is producing its extracellular matrix.
4. Bone tissues are richly supplied by blood and lymph tissues through specialized connecting channels called Haversian and Volkmann channels. Cartilages are avascular; thus, they lack any such channels.
5. The bone grows bidirectional while cartilage grows uni-directionally.
6. Bones provide rigid support, providing shape and protection to all organs during cartilage helping in elasticity and compressibility for smooth function along with support.

References

1. https://www.sciencedirect.com/science/article/pii/875632829390081K
2. https://www.sciencedirect.com/science/article/pii/S108495210090243X