Connective Tissues

Functions of connective tissues

• ·      Connects

• ·      Underlines

• ·      Surrounds

• ·      Produces and maintains many different intracellular substances

• ·       Provides support and nourishment

•  Classification of connective tissues

Characteristics of connective tissues

• Common origin
• Cells are spread through an extracellular fluid ( ratio ECM;Cell - high )
• Ground substance
• Presence of fibers
• Function - similar

Types of connective tissue fibers

Three types of fibers

- collagen fibers

        strongest and most

        abundant

        Tensile strength> steel

- Elastic fibers

        yellow fibers

        long,thin,branching fibers

        can stretch and recoli

- Reticular fibers

        fine collagenous fibers

ECM

• Collection of extracellular molecules secreted by cells
• Provides structural and biochemical support to the surrounding cells
• ECM varies for different tissues and provides their structural and functional features

            Examples

                    fluid part of blood

                    hard part of bones

                    tough part of fascia

                    resilient part of cartillage

Functions of connective tissues

- depends on,

    types of cells

    fibers involved

- Loose and dense irregular connective tissue

    provide medium for transport

    allow organs to resist stretching and tearing forces

- dense regular connecting tissue

    forms organized structure

  

- elastic fibers

    provide resistance to stretch forces

- reticular fibers

    provide the stroma - or structural support

    for the parenchyma - or functional part of the organ

Connective tissue proper

• Consists of cells and extracellular matrix, including fibers and ground substance

    - Loose - has predominance of ground substance / usually irregular

    - Dense - has predominance of fibers

    - Regular - fibers form parallel bundles

    - Irregular - fibers are disordered

Functions of connective tissue proper

• Mechanical support
• Protection
• Exchange of metabolites
• Homeostasis
• Protection against infection
• Repair after injury,plastic function

Loose connective tissue

- Characterized by loosly arranged fibers and an abundance of cells

Primary locations

    - beneath those epithelia that cover the body surfaces and line internal surfaces of the body

    - in association with the epithelium of glands 

    - surrounds the small vessels

Dense connective tissue

-Dense irregular connective tissue

    

    - characterized by an abundance of fibers and few cells. Collagen fibers irregularly arranged

    - it forms the reticular or deep layer of the dermis

    - tissue can resist tention from any direction

Dense regular connective tissue

- characterized by parallel , ordered and densely packed arrays of fibers and cells

- main functional component of tendons, ligaments, aponeurones

- tensile strength in one direction

Connective tissue - Specialized

Adipose

• Location - deep to skin; sides , buttocks , breasts, padding around eyeball and kidneys
• Function - insulation , mechanical support , stores energy

Reticular

• Location - spleen , lymph nodes, bone marrow
• Function - supporting framework for haemopoietic organs

Cartilage

• Composed - Chondrocytes and their surrounding matrix
• 3 types of cartilage that are distinguished based on their matrix characteristics

                - Hyaline cartilage

                - Fibrocartilage

                - Elastic cartilage

- Hyaline cartilage

Locations

- embryonic skeleton

- ends of the ling bones in joint cavities

- cartilage of the nose

- trachea

- larynx

- coastal cartilage of the ribs

- Elastic cartilage

Locations

- external ear

- epiglottis

-Fibrocartilage

Locations

-intervertebral discs

- public symphysis

Bone

• Specialized connective tissue with a mineralized extracellular matrix
• Consists of three cell types
• osteoprogenitor cells
• osteoblasts ( osteocytes when differeniated )
• osteoclasts

Blood

• Transport of respiratory gases,nutrients and other waste substances