Class 11 Biology Structural Organisation In Animals Connective tissues

Connective tissues

  • The special tissues which link and support other tissues/organs of the body are called connective tissues.
  • Connective tissues include cartilage, bone, adipose, and blood.
  • In all connective tissues except blood, the cells secrete fibres of structural proteins called collagen or elastin.
  • Connective tissues are classified into three types
  • Loose connective tissue
  • Dense connective tissue and
  • Specialized connective tissue
  • Loose connective tissue has cells and fibres loosely arranged in a semi-fluid ground substance.

For example-

Areolar tissue present beneath the skin contains fibroblasts, macrophages.

Class_11_Biology_Structural_Organization_Areolar_Tissue

Fig. Areolar tissue

 Adipose tissue is located mainly beneath the skin, which is specialized to store fats.

Class_11_Biology_Structural_Organization_Adipose_Tissue

Fig. Adipose tissue

  • Fibres and fibroblasts are compactly packed in the dense connective tissues.
  • Orientation of fibres shows a regular or irregular pattern and are called dense regular and dense irregular tissues, respectively.
  • In the dense regular connective tissues, the collagen fibres are present in rows between many parallel bundles of fibres.

Examples –

  • Tendons which attach skeletal muscles to bones
  • Ligaments which attach one bone to another.

Class_11_Biology_Structural_Organization_Tendons_&_Ligaments

Fig. Tendons and ligaments

  • Dense irregular connective tissue has fibroblasts and many fibres oriented differently and are present in the skin.
  • Cartilage, bone and blood are types of specialized connective tissue.

Cartilage

  • The intercellular material of cartilage is solid and pliable and resists compression.
  • Cells of this tissue called as chondrocytes are enclosed in small cavities within the matrix secreted by them.
  • Cartilage is present in the tip of nose, outer ear joints, between adjacent bones of the vertebral column, etc.

Class_11_Biology_Structural_Organization_Cartilage

Fig. Cartilage

Bone

  • Bones have a hard and non-pliable ground substance rich in calcium salts and collagen fibres which give bone its strength.
  • Bones support and protect softer tissues and organs.
  • The bone cells (osteocytes) are present in the spaces called
  • They interact with skeletal muscles attached to them to bring about movements.
  • The bone marrow in some bones is the site of production of blood cells.

Class_11_Biology_Structural_Organization_Bone

Fig. Bone

Blood

  • Blood is a fluid connective tissue containing plasma, red blood cells (RBC), white blood cells (WBC) and platelets.
  • Blood is the main circulating fluid that helps in the transport of various substances.

Class_11_Biology_Structural_Organization_Blood

Fig. Blood

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