Connective
Tissue
• Connective tissues are most
abundant and widespread in the body of complex animals and are named as
connective tissues due to their special function of linking and supporting other
tissues/organs of the body. They range from soft connective tissues to
specialised types, which include cartilage, bone, adipose, and blood.
• In all connective tissues except
blood, the cells secrete fibres of structural proteins called collagen or elastin.
The fibres provide strength, elasticity and flexibility to the tissue. These
cells also secrete modified polysaccharides, which accumulate between cells and
fibres and act as matrix (ground substance).
Connective tissues are of three
types:
·
Loose connective tissue
·
Dense connective tissue
·
Specialised connective tissue
Loose connective
tissue:
• Loose connective tissue has
cells and fibres casually arranged in a semi-fluid ground substance, example, areolar tissue present underneath the skin. Often it assists
as a support framework for epithelium. It comprises fibroblasts (cells that
produce and secrete fibres), macrophages and mast cells.
Loose connective tissue
: Areolar tissue
• Adipose tissue is another type
of loose connective tissue located mostly beneath the skin. The cells of this
tissue are specialised to store fats and the excess of unused nutrients are
changed into fats and are stored in this tissue.
Loose connective tissue
: Adipose tissue
Dense connective
tissue:
• Fibres and fibroblasts are
compactly packed in the dense connective tissues. Orientation of fibres show a
regular or irregular pattern and are called dense regular and dense irregular
tissues.
Dense regular
connective tissue:
• In the dense regular connective
tissues, the collagen fibres are present in rows between many parallel bundles
of fibres. Tendons, which attach skeletal muscles to bones and ligaments which
attach one bone to another are examples of this tissue.
Dense connective tissue
: Dense regular
Dense irregular
connective tissue:
• Dense irregular connective
tissue has fibroblasts and many fibres (mostly collagen) that are oriented
differently. This tissue is present in the skin.
Dense connective tissue :
Dense irregular
Specialised
connective tissue:
• Cartilage, bones and blood are
various types of specialised connective tissues.
Cartilage:
• The intercellular material of
cartilage is solid and pliable and struggles density. Cells of this tissue
(chondrocytes) are walled in small cavities within the matrix secreted by them.
Most of the cartilages in vertebrate embryos are replaced by bones in adults.
Specialised connective tissues : Cartilage
• Cartilage is present in the tip
of nose, outer ear joints, between adjacent bones of the vertebral column,
limbs and hands in adults.
Bones:
• Bones have a hard and non-pliable
ground substance rich in calcium salts and collagen fibres which provide bone
its strength. It is the main tissue for structural frame to the body, bones
support and protect softer tissues and organs.
Specialised connective tissues : Bones
• The bone cells (osteocytes) are
present in the spaces called lacunae. Limb bones, such as the long bones of the
legs, perform the weight -bearing functions and they also 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.
Blood:
• Blood is a fluid connective
tissue containing plasma, red blood cells (RBC), white blood cells (WBC) and
platelets. It is the main circulating fluid that supports in the carriage of many
substances.
Specialised connective tissues : Blood
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