Cell junction :
- Cells of the epithelium are held together with little intercellular matrix.
- Cell junction provide structural and functional link between the cells
- Tight junction: help to stop substances from leaking across a tissue.
- Adhering junctions: perform cementing to keep neighboring cells together.
- Gap junctions: facilitate the cells to communicating the cytoplasm of adjoining cells, for rapid transfer of ions, small molecules.
Connective tissues :
- Most abundant and widely distributed tissues.
- Special function of linking and supporting other tissues/organs of the body.
- Connective tissues include cartilage, bone, adipose, and blood.
- In all connective tissue except blood, the cells secrete fibres of proteins called collagen and elastin.
- The fibre provides strength, elasticity and flexibility to the tissue.
- Presence of ground substance or matrix in between the cells, modified polysaccharides.
Loose connective tissue :
- Has cells and fibres loosely arranged in a semisolid ground substance.
Areolar tissue :
- Areolar tissue is one example of loose connective tissue.
- Present beneath the skin.
- It supports the framework for epithelium.
- It contains cell like fibroblasts (secretes fibres), macrophages and mast cells.
Adipose tissue:
- Another type of loose connective tissues.
- Located mostly beneath the skin.
- Cells of this tissue specialized to store fats called adipocytes.
Dense connective tissue :
- Fibres and fibroblasts are compactly packed.
Dense regular tissues :
- Orientation of fibres shows a regular pattern.
- The collagen fibres are present in rows between many parallel bundles of fibres.
- Tendons: joints muscles to bone.
- Ligaments: joins bone to bone are the examples.
Dense irregular tissues:
- Fibroblasts and many fibres are oriented differently.
- This tissue present in skin.
Specialized connective tissues :
- Cartilage bone and blood are the special connective tissues.
Cartilage:
- Intercellular material of cartilage is solid.
- Chondrocytes are the cells of cartilage.
- Pliable and resists compression.
- Cells are enclosed in small cavities within the matrix.
- Most of the cartilage of the embryo replaced by bones in adult.
- Cartilage present in nose tips, ear pinna, between adjacent vertebrae.
Bones:
- Have hard and non pliable matrix or ground substance.
- The matrix is rich in calcium salts and collagen fibers which give the bone its strength.
- Provides the structural frame of human body.
- Support and protect the soft tissues and organs.
- The bone cells called Osteocytes are present in fluid filled cavity called lacunae.
- Sustain body weight.
- Attached with skeletal muscles meant for locomotion.
- Bone marrow is the site of production of Red blood cells.
Muscular tissues:
- Each muscle is made of many long, cylindrical fibres arranged in parallel arrays.
- Each fibre composed of numerous fine fibrils, called myofibrils.
- Muscle fibres contracts in response to stimulus.
- Muscle plays a great role in movement and locomotion.
Skeletal muscle:
- Closed attached to the skeleton or bone and cartilage.
- Muscle cells are unbranched and multinucleated.
- A number of muscle fibres are bundled together in parallel fashion.
- A sheath of tough connective tissues encloses several bundles of muscle fibres.
