Connective Tissue

There are four primary tissue types in the body;

• Epithelial tissue - sheets of tightly bound cells, found covering exposed areas and lining internal cavities

  • Ex: founds in skin, digestive tract and kidneys, provided protection and selective absorption

    • If the tissue is not tightly packed in the digestive tract it results in gaps where nutritions are able seep through causing abdominal inflammation

• Connective tissue - provides support and structure

• Muscular tissue - can contract and produce movements

• Neural tissue - conducts electrical impulses

Connective tissue

All connective tissue have 3 main components:

• Specialized cells that are specific to the type of connective tissue that they are

• Have extracellular protein fibers

• Have a matrix

Classification of connective tissue, there are 3 categories:

• Connective tissue proper - has a fibrous matrix

• Fluid connective tissue - has a liquid matrix

• Supporting connective tissue

Functions of connective tissue

• Establishing the structural framework of the body (bone/skeleton)

• Transporting fluid and dissolved materials

• Protecting organs (provides coating and bony housing/skull ribs)

• Supporting, surrounding, and connecting other tissues

• Storing energy (adipose tissue/fat)

• Defending the body from microorganisms

  

Connective tissue Proper

• Loose connective Tissues - loose fibers

• Areolar tissue

  

  • Loose fiber matrix

  • Found deep in the dermis

  • Binds the skin to muscles

  • Provides minimal supports

  • Allows for a lot of movement (elastic fibers)

• Adipose tissue

  • Has adipocytes (white and brown)

  • White adipose cells (loose fibrous matrix)

    • Found in the hypodermis (the fat layer between fat and muscle) mainly in the buttock region and around organs

    • A type of energy storing tissue

    • Provides a “cushioning” function and an insulator

  • Brown adipose tissue (loose fibrous matrix)

    • Seen mainly in infants and young children

    • Brown because they have their own blood supply

    • Provided a heat source

      

    • Is seen in some adults, studies conducted to see is this can be used to combat obesity

• Reticular tissue

  • Found in tissues and organs

    • Liver, spleen, kidney, lymph nodes, appendix, bone marrow, tonsils and more

    • Its orientations of reticular fibers allow the tissue to provide a supporting/scaffolding framework to all the organs its found in

• Dense connective tissue

  • Dense regular connective tissue (Still dense fibrous matrix)

    • The density of the tissue provides its strength

      

    • Found in tendons (bind muscle to bone)

      • Aponeurosis (broad sheet like tendon found at the top of the head and palm)

      • Ligaments (connects bone to bone and soft structures/organs internally)

    • Note the fibers in the image are organized neatly and densely packed

      

  • Dense irregular connective tissue (dense fibrous matrix)

    • Tissue is a dense “mess” with bundles

    • Provides strength and support, though not as strong as regular connective tissue

    • Found in fibrous capsules around organs, dermis of skin, glands, some visceral organs (internal), outer layer of bones (creates a capsule around the bone - periosteum), outermost layer of cartilage (pericardium)

    • Note the fibers in the image are not as neatly packed

      

  • Elastic tissue (dense fibrous matrix

    • A type of dense connective tissue but with more elastic fibers in the tissue

    • Found in fascia (covers the skeletal muscle) and the vertebrae (stabilized the spinal cord)

• Fluid connective tissue (liquid Matrix)

  • Blood - located in the cardiovascular system.

    • Specialized cells include: erythrocytes (red blood cells), leukocytes (white blood cells), and platelets

  • Lymph - located in the lymphatic system

    • Specialized cells include: lymphocytes (plays a vital role in the immune system)

• Supporting connective tissue

  • Provides a strong framework that supports the rest of the body

    • Cartilage - made of chondrocytes (specialized cells)

      • Has a gelatinous matrix

      • Chondroitin Sulfate - a protein found in the matrix

      • Is avascular, has no blood supply, not easily healed

    • Bone - made of osteocytes (specialized cells)

      • Solid matrix

      • Has calcium phosphates

      • Very strong

Three types of cartilage

• Hyaline

  • found between ribs and sternum (center breast bone), several structures along the throat region (larynx, trachea, windpipe, bronchi), some joints in elbows and knees, and immature skeleton (newborn) before it calcifies)

  • Provided flexible support and helps reduce friction

• Elastic

  • Found in external part of ear (auricle), auditory canal, epiglottis

  • Provides flexible support

• Fibrous

  • Found in tissue to bone attachment (where ligaments and tendons connect), menisci in knees, pubic symphysis ( where pubic bone need the front of lower region of the groin), and intervertebral disks (in the spinal cord)

  • Provides resistance to compression (important in vertebrates), absorbs shock, and is very strong

Two types of bone

• Compact - surrounds the spongy bone and holds blood vessels

  • Blood vessels are trapped in central/haversians canals in the osteons (considered the functional unit of compact bones, has everything needed to allow the bone to function)

  • Canaliculi - channels between lacunae and blood vessels that leaf out to the surface of the osteon, allows for transportation

  • Periosteum - made up of fibrous layer and a cellular level. The outermost layer of all bone (dense irregular connective tissue)

• Spongy - (trabecular/cancellous bone) located on the inside of the bone

The connective tissue framework of the body

• connective tissue creates the internal framework of the body

• layers of connective tissue, called fascia (surrounds organs and covers muscles), connect organs with the rest of the body

  • Superficial fascia (subcutaneous layer) - loose connective tissue, areola and adipose tissue

  • Deep fascia - dense irregular connective tissue

  • Subserous fascia - deeper layer, loose connective tissue, areola

Myofascial - Deep fascia

*myofascial - fascia around the muscle

• Fascia covering the skeletal muscle

• Myofascial pain syndrome - chronic pain disorder

  • Pressures on sensitive points in the muscle triggers pain in unrelated parts of the body

  • Referred pain

Tissue and aging

• Repair and maintenance become less efficient as one ages

• Hormonal changes and lifestyle changes also affect the functioning of tissues

• connective tissue become fragile

• A reduction in bone strength; osteoporosis

Myo = muscle

Peri = outside/surrounding layer

Osteo = bone

Chondro = cartilage