Part II: Connective Tissue

Connective Tissue

Most abundant and widely distributed tissue

Main classes:

1. Connective tissue proper (loose & dense)

2. Cartilage

3. Bone

4. Blood

Functions:

1. Binding and support

2. Protection

3. Insulation

4. Transport substances

Classification

Variations in blood supply

Avascular (no blood) – cartilage

Poorly vascular – tendons, ligaments

Extracellular matrix

Produced by cells, secreted to exterior

Ground substance: “glue” - fills space between cells & fibers

water + adhesion proteins + polysaccharides

Fibers: provide support

Collagen - strength

Elastic – stretch

Reticular – fine network, “skeleton” of organs

Loose Connective Tissue

Universal packing material

Subclasses: areolar, adipose, reticular

Structure: softer, fewer fibers, gel-like matrix

Functions:

Cushion & protect organs (areolar, fat)

Store nutrients (fat)

Internal framework (reticular)

Fight infection (areolar)

Cells: fibroblasts, adipocytes (fat cells)

Locations: under skin, lymph nodes, hips, behind eyeballs

Dense Connective Tissue

Tendons & ligaments

Subclasses: dense regular, dense irregular, elastic

Structure: mainly collagen fibers

Functions:

Elastic

Resist tension

Cells: fibroblasts

Locations: tendons (muscle-bone), ligaments (bone-bone), lower layers of skin

Cartilage

Subclasses: hyaline, elastic, fibrocartilage

Structure: flexible, no nerves or blood

Functions:

Support

Compression

Cells: chondroblasts, chondrocytes

Locations: larynx, joints, tip of nose, ear, intervertebral discs, rib-breastbone, knee joint

Bone

Osseous tissue

Subclasses: compact, spongy

Structure: hard, calcified matrix; blood vessels

Functions:

support & protect

Store calcium

Blood cell formation (marrow)

Cells: osteoblasts, osteocytes

Locations: bones

Blood

Vascular tissue

Subclasses: blood cells, plasma

Structure: fluid within blood vessels, no fibers

Functions:

Transport vehicle (nutrients, wastes, gases, hormones)

Cells: white blood cells (leukocytes), red blood cells (erythrocytes), platelets

Locations: blood vessels