Supportive connective tissue: Cartilage and Bone




Supportive connective tissue: Cartilage and Bone

  • They are supporting tissue, forms endoskeleton of vertebrates, protect vital organs
  • types-
  1. Cartilage: Hyline cartilage, elastic cartilage and fibrous cartilage
  2. Bone: spongy bone and compact bone

1. Cartilage:

  • It is tough, hard but a flexible connective tissue. It can resist strain and can absorb mechanical shock.
  • It consists of solid or semisolid matrix in which cartilage cell (chondrocytes) and fibres are embedded.

Structure:

  • cartilage is enclosed in a sheath of white fibrous connective tissue called Below the perichondrium, there is layer chondroblast cell, which form chondrocytes.
  • Chondrocytes are dispersed in the matrix and occur in the fluid filled space called lacunae.
  • Each lacunae contain 2-4 chondrocytes. Each chondrocytes is a large, angular cell with distinct nucleus.
  • The matrix lacks the blood vessels.

types:

  • Depending upon matrix, cartilage are of 3 types

i. Hyaline cartilage:

  • The matrix is glass like semi transparent, homogenous and has fine collagen fibres
  • It is slightly elastic and compressible.
  • Found in- nose, larynx, trachea, ends of bone. It forms skeleton of cartilage fish

ii. Elastic cartilage:

  • The matrix is semi opaque and has network of yellow elastic fibres
  • It is highly elastic and flexible. The tissue recover the shape quickly
  • Found in-external ear, epiglottis, and pharynx (Eustachian tube)

iii. Fibrous cartilage:

  • The matrix has bundles of densely packed white collagen fibres
  • It provides great strength and little degree of flexibility
  • It acts as a shock absorber by giving a cushioning effect
  • Found in- intervertebral discs and at pubis symphysis

2. Bone:

  • It is supportive and protective tissue.
  • The matrix is solid and calcified. (70% salts of calcium and phosphate: hydroxyapatite-Ca10(PO4)6(OH)2, 30 %fibrous protein; Ossein).
  • Bone cell (Osteocyte) and collagen fibre are embedded in solid matrix

Structure:

  • Each bone is enclosed in a layer of white fibrous connective tissue, called periosteum.
  • Matrix is arranged in concentric circles called lamellae.
  • Number of osteoblast cell and osteocytes are arranged in between the lamellae, in the fluid filed space called Lacunae.
  • Each lacunae has fine cytoplasmic processes called canaliculi, which connect with other lacunae.
  • Osteoblast are active bone cell, while osteocytes are inactive osteroblats

types:

i. Compact bone:

  • Compact bone is arranged in concentric ring structures called osteons (Haversian canal system) in the center of each ring is a structure called a Haversian canal. This canal carries blood vessels through
    the bone to nourish the cells embedded within the tissue.
  • Around the Haversian canal, rings of bone tissue are found called lamellae. Within these rings, are space called lacunae that contain osteocytes
  • Radiating out from the lacunae are tiny channels that allow interaction of the cells with the blood supply,exchanges of nutrients, gases, called canaliculi.
  • Canal of Volkman connects various Haversian canal systems together
  • In the centre of compact bone, bone marrow cavity is present, filled with yellow bone marrow

ii. Spongy bone:

  • The matrix is web like rather than solid with number of space in between.
  • Also known as trabeculae
  • Found in epiphysis of long bone
  • It lacks Haversian canal system and Volkman canal
  • It contains red bone marrow, which forms RBC and WBC.

Supportive connective tissue: Cartilage and Bone