Difference Between Bones and Cartilage

Bones and cartilage are types of connective tissues that are composed of cells embedded within an extracellular matrix. Bones are hard connective tissue, whereas cartilage is soft connective tissue. Bones compose the skeletal structure of the body and protect against the mechanical damage and support to the movement of the body and provide shape to the body. In contrast, cartilage is present in the nose, ribs, ears, joints, larynx and other flexible parts of the body.

Bones and cartilage are also responsible for the movement and locomotion of the body. Both protect the delicate organs from the internal and external shock.

Comparison Chart

Basis for Comparison Bones Cartilage
Definition Bones are the complex structures made up of connective tissues that are hard and provide protection and shape to the body. Cartilage is the simple structure of the body made up of connective tissue, which is soft and useful in providing flexibility to the joints and also protects from the internal and external shocks.
Bending Cannot bend Can bend
Composition Proteins, calcium and phosphorous Proteins and sugars
Vascularity Vascular Non-vascular
Growth pattern Bidirectional Unidirectional
Porosity Porous Non-porous
Metabolic activity High Low
Oxygen demand High Low
Repair capabilities Extensive repair capability Limited repair capability
Cells Osteoblasts, osteocytes and osteoclasts Chondrocytes and chondroblasts
Types Two types:

Compact bones

Spongy bones

Three types:

Fibrocartilage

Elastic cartilage

Hyaline cartilage

What are Bones?

Bone is the rigid tissue of the body composed of a material such as a collagen and calcium phosphate. It is made up of connective tissue. Bones form the skeletal system of the human body and in other vertebrates. The human adult body has 206 bones. The smallest bone is the stapes found in the middle ear, whereas the largest bone is the femur, which is the thigh bone.

Bones are usually hard due to the deposition of the phosphates and carbonates of the calcium in the matrix. The bone matrix has proteins called ossein and can be both organic and inorganic. They occur in lamellae and are vascular. Bones have the deposit of calcium salts of calcium phosphate.

Types

Bones can be classified based on shape and location. Based on shapes, bones are grouped into five types; flat, long, short, irregular and sesamoid. Whereas based on location, bones are of two types; compact and spongy bones. Compact bones are present on the outer layer of the bones, whereas spongy bones are present in the inner part of the long bones.

Functions

Bones form the skeletal system of the body of the vertebrates. Vertebrates are the only living bodies on the earth whose body consists of the bones. Almost 99% of their body is present in the bones and teeth and the remaining 1% is found in the blood.

Bones perform the following functions:

They provide the structural support to the soft tissue and internal organs against the different mechanical actions performed by them like contraction and relaxation of the muscles of the heart and lungs.

Bones also act as a protective site for the special tissues like bone marrow.

Bones also give shape to the body and store minerals where it controls the level of calcium and phosphate in the body fluids.

What is Cartilage?

Cartilage is the soft kind of connective tissue. It is a very firm tissue responsible for the bending, flexibility and muscular stretching. Cartilage lacks the blood vessels so the growth of these connective tissues is very slow.

Cartilage is the extracellular matrix present in the connective tissues. Cartilages possess chondrocytes which are formed from the precursor cells chondroblasts. Chondroblasts produce a matrix of collagen and elastin fibers in which chondrocytes are embedded. Lacunae are the spaces where these cells lie. Each lacuna has two to three chondrocytes. The chondrocytes determine the level of flexibility in the cartilage. The matrix of the cartilage has a protein called chondrin and is organic and homogenous. The matrix of cartilage does not possess calcium salt, so they are soft.

Types

Cartilage is of three types; elastic cartilage, hyaline cartilage and fibrocartilage.

  1. Elastic Cartilage: This type of cartilage is present in the ear. It is very flexible, which means it possesses more chondrocytes.
  2. Hyaline Cartilage: This type of cartilage is present in the nose and at the end of the ribs. Hyaline cartilage is the second most flexible type of cartilage.
  3. Fibro Cartilage: This type of cartilage is present in the knee as well as in the spinal column. It possesses a fewer number of chondrocytes.

Functions

Cartilage’s main function is to connect the bones. Cartilage is present at the places whereas flexibility is required, such as in joints, ribs, ankles, knees, elbows, nose, ears, bronchial tubes and spinal column. It acts as a shock absorber.

Key Differences

  1. Bones are complex connective tissue which forms the skeletal system, whereas cartilage is the simple connective tissue found in some organs.
  2. Bones are tough, rigid and non-flexible, whereas cartilage is soft, elastic and inflexible.
  3. Bones grow in both directions, whereas cartilage grows in one direction.
  4. In bones, hemopoietic tissue (bone marrow) is present, whereas homoeotic tissue is absent in cartilages.
  5. Bone cells are called osteocytes, whereas cartilage cells are called chondrocytes.
  6. In bones, the matrix is both organic and inorganic, whereas the matrix is organic in cartilage.
  7. Bone matrix is composed of calcium, phosphorous and proteins, whereas the cartilage matrix is composed of proteins and sugar.
  8. Bones have deposition of calcium salts, whereas cartilages may or may not have calcium salts.
  9. Bones play a role in the blood supply, whereas cartilage does not participate in blood supply except in perichondrium.
  10. Metabolic activity is high in the bones, whereas metabolic activity is low in the cartilage.
  11. Bones are of two types; compact and spongy bones, whereas cartilage is of three types; elastic, hyaline and fibrocartilage.

Key Similarities

  1. Both bones and cartilage are types of connective tissues.
  2. Both bones and cartilage protect the internal organs.

Conclusion

In conclusion, both bones and cartilage are specialized connective tissues. Both perform the role of protection for the organs and support to the body. The major difference is that bones are hard, whereas cartilages are soft.

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