7.1.3 Structure of Cartilage

Cartilage is a flexible connective tissue found in various parts of the body. It is not as strong as bone but is more flexible because its matrix is gel-like and contains many collagenous and elastic fibers. Cartilage is covered by a dense layer of collagen fibers called the perichondrium.

Definition

Cartilage: Cartilage is a flexible connective tissue that is not as strong as bone. It is present at particular places only. It is more flexible than the bone because the matrix is gel like and contains many collagenous and elastic fibres.

Perichondrium: The cartilage matrix is covered by a dense layer of collagen fibres, called perichondrium.

Chondrocytes: The living cells of cartilage are called chondrocytes.

Main Idea

• Cartilage is not as strong as bone.
• It is present at particular places only.
• It is more flexible than bone.
• The matrix is gel-like.
• The matrix contains many collagenous and elastic fibres.
• The cartilage matrix is covered by a dense layer of collagen fibres called the perichondrium.
• There are many small cavities distributed in the matrix called lacunae.
• Lacunae contain cartilage cells.
• The living cells of cartilage are called chondrocytes.
• Cartilage does not contain blood vessels.
• Chondrocytes are supplied by diffusion.
• Because of this, cartilage heals very slowly.
• There are three types of cartilage:

Core Concept

• Cartilage = flexible connective tissue
• Perichondrium = dense layer of collagen fibres covering cartilage
• Lacunae = small cavities in matrix
• Chondrocytes = living cells of cartilage
• No blood vessels = cartilage does not contain blood vessels
• Heals slowly = due to lack of blood vessels
• Types = hyaline, fibrocartilage, elastic

Detailed Explanation

Structure of Cartilage

• Cartilage is not strong as bone.
• It is present at particular places only.
• It is more flexible than the bone because the matrix is gel like and contains many collagenous and elastic fibres.
• The cartilage matrix is covered by a dense layer of collagen fibres, called perichondrium.
• There are many small cavities distributed in the matrix called lacunae which contain cartilage cells.
• The living cells of cartilage are called chondrocytes.
• Unlike other connective tissues, cartilage does not contain blood vessels and the chondrocytes are supplied by diffusion.
• Because of this, it heals very slowly.
• Although the human skeleton is initially made up of cartilages and fibrous membranes, most of these early supports are soon replaced by bones.
• A few cartilages that remain in adults are of three types.

Types of Cartilage

Summary Table of Cartilage Structure

Intermediate Level

Structure of Cartilage

Types of Cartilage

Comparison of Cartilage and Bone

Formula / Mathematical Form

Not applicable to this topic.

Solved Example

Not applicable to this topic (descriptive topic).

Important Points

• 1. Cartilage is a flexible connective tissue.
• 2. It is not as strong as bone.
• 3. It is present at particular places only.
• 4. It is more flexible than bone.
• 5. Matrix is gel-like.
• 6. Matrix contains collagenous and elastic fibres.
• 7. Perichondrium is a dense layer of collagen fibres.
• 8. Lacunae are small cavities in matrix.
• 9. Chondrocytes are living cells of cartilage.
• 10. Cartilage does not contain blood vessels.
• 11. Chondrocytes are supplied by diffusion.
• 12. Cartilage heals very slowly.
• 13. Human skeleton is initially made of cartilages.
• 14. Most early supports are replaced by bones.
• 15. Three types of cartilage remain in adults.
• 16. Hyaline cartilage is at the ends of long bones.
• 17. Fibrocartilage is in disks between vertebrae.
• 18. Elastic cartilage is in ear flaps and epiglottis.
• 19. Cartilage provides flexible support.
• 20. Cartilage cushions joints.

Remember

• - Cartilage = flexible connective tissue
• - Perichondrium = dense layer of collagen fibres covering cartilage
• - Lacunae = small cavities in matrix
• - Chondrocytes = living cells of cartilage
• - No blood vessels = cartilage does not contain blood vessels
• - Heals slowly = due to lack of blood vessels
• - Types = hyaline, fibrocartilage, elastic
• - Hyaline = ends of long bones, nose, larynx, trachea
• - Fibrocartilage = disks between vertebrae, knee
• - Elastic = ear flaps, epiglottis

Common Mistakes

• 1. Confusing cartilage and bone — Cartilage = flexible; bone = strong.
• 2. Forgetting that cartilage lacks blood vessels — Cartilage does not contain blood vessels.
• 3. Mixing up the types of cartilage — Hyaline, fibrocartilage, elastic.
• 4. Forgetting the role of perichondrium — Covers the cartilage.
• 5. Mixing up the locations — Hyaline: ends of bones; fibrocartilage: vertebrae; elastic: ear flaps.
• 6. Thinking cartilage heals quickly — Cartilage heals very slowly.
• 7. Confusing chondrocytes and osteocytes — Chondrocytes = cartilage; osteocytes = bone.
• 8. Believing cartilage is not important — Cartilage provides flexible support and cushions joints.
• 9. Mixing up lacunae and matrix — Lacunae are cavities; matrix is the ground substance.
• 10. Forgetting the role of diffusion — Chondrocytes are supplied by diffusion.

Quick Revision

Cartilage is not strong as bone. It is present at particular places only. It is more flexible than the bone because the matrix is gel like and contains many collagenous and elastic fibres. The cartilage matrix is covered by a dense layer of collagen fibres, called perichondrium. There are many small cavities distributed in the matrix called lacunae which contain cartilage cells. The living cells of cartilage are called chondrocytes. Unlike other connective tissues, cartilage does not contain blood vessels and the chondrocytes are supplied by diffusion. Because of this, it heals very slowly. Although the human skeleton is initially made up of cartilages and fibrous membranes, most of these early supports are soon replaced by bones. A few cartilages that remain in adults are of three types. Hyaline cartilage is found at the ends of long bones and in the nose, at larynx and trachea. Fibrocartilage contains wide rows of thick collagenous fibres is found in the disks located between the vertebrae, cartilage of knee. Elastic cartilage is found in the ear flaps and epiglottis.

60-Second Revision

• Cartilage = flexible connective tissue
• Perichondrium = dense layer of collagen fibres covering cartilage
• Lacunae = small cavities in matrix
• Chondrocytes = living cells of cartilage
• No blood vessels = cartilage does not contain blood vessels
• Heals slowly = due to lack of blood vessels
• Types = hyaline, fibrocartilage, elastic
• Hyaline = ends of long bones, nose, larynx, trachea
• Fibrocartilage = disks between vertebrae, knee
• Elastic = ear flaps, epiglottis
• Warning: Cartilage has no blood vessels and heals very slowly

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• 7. Support and Movement

• Topic:
• 7.2 DIVISIONS OF HUMAN SKELETON

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