Adipose Tissue (Loose Connective Tissue) Warm-Up What type of connective tissue is shown below? 1. 2. Adipose Tissue (Loose Connective Tissue) Cartilage 3. 4. Bone Blood

Tissue: The Living Fabric Chapter 4 Tissue: The Living Fabric

Part II: Connective Tissue

Connective Tissue Most abundant and widely distributed tissue Main classes: Connective tissue proper (loose & dense) Cartilage Bone Blood Functions: Binding and support Protection Insulation Transport substances

Connective Tissue General Features Not very cellular compared to the other types of tissue Does not occur on body surfaces Has a nerve supply, except cartilage Variations in blood supply Avascular (no blood) – cartilage Poorly vascular – tendons, ligaments

Two basic elements: cells and an extracellular matrix Cells -blasts : form the extracellular matrix -cytes : maintain the extracellular matrix -clasts : break down the extracellular matrix

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, aorta (elastic)

Dense Irregular Connective Tissue

Elastic Connective Tissue in the Aorta

Cartilage Subclasses: hyaline, elastic, fibrocartilage Structure: flexible, no nerves or blood Functions: Support Compression Matrix: Lacuna – little spaces that house the cells; ground substance is flexible 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 (red marrow) Lipid (fat) storage (yellow marrow)

Bone Matrix: Lacuna and Canaliculi – little canals that connect the Central Canal to lacuna to transport nutrients, oxygen etc. to cells. Cells: osteoblasts, osteocytes Locations: bones (skeleton)

Blood Vascular tissue Structure: fluid within blood vessels, fibers only present during clotting Functions: Transport vehicle (nutrients, wastes, gases, hormones) Cells: white blood cells (leukocytes), red blood cells (erythrocytes), platelets Locations: blood vessels