Connective Tissue The dense layer of the basal lamina of all epithelial tissue is created by connective tissue. Connective tissue connects the epithelium to the rest of the body.

Three Basic Components Specialized cells Fibroblasts Adipocytes Extracellular protein fibers Collagen fibers Reticular fibers Elastic fibers A fluid known as ground substance CT vary widely in appearance and function, but they all share three basic components. Extracellular fibers and ground substance together make up the matrix which surrounds cells. Cells make up most of epithelial cells, matrix makes most of volume in CT. Fibroblasts secrete a polysaccharide derivative responsible for making ground substance viscous and protein subunits that make the assemble to form extracellular fibers. Adipose=fat cells, each cell contains enourmous lipid droplet

Functions of Connective Tissue Establishing a structural framework for the body. Transporting fluids and dissolved minerals. Protecting delicate organs. Supporting, surrounding, interconnecting other types of tissue. Storing energy reserves Defending the body from invading microorganisms.

Classification of Connective Tissues Classified based on their physical properties. Three categories: Connective Tissue Proper Ex. Adipose tissue Fluid Connective Tissue Ex. Blood and Lymph Supportive Connective Tissue Ex. Cartilage and bone

Connective Tissues Connective Tissue Proper Fluid Connective Tissues Supporting Connective Tissues LOOSE DENSE Fibers create loose, open framework. “Packing materials” Adipose Areolar Reticular Fibers densely packed Dense regular Dense Irregular Elastic BLOOD LYMPH Contained in cardiovascular system Contained in lymphatic system Loose= fills spaces between organs, cushion and stabilize specialized cells, and support epithelia. Surround and support blood vessels and nerves, store lipids, and provide a route for diffusion of material. CARTILAGE BONE Solid, rubbery matrix Hyaline Elastic Fibrocartilage Solid, crystalline matrix

Mesenchyme Tissue Function: Give rise to all other connective tissues of an embryo and all various cell types of adult connective tissue. Found in abundance during early development of most animals. Embryonic connective tissue, first tissue to appear, star shaped mesenchymal cells, Adults don’t have embryonic connective tissue however, contain mesenchymal stem cells that can assist in tissue repair.

Loose Connective Tissue Adipose Tissue Location: Deep to the skin, especially at sides, buttocks, padding around eyes and kidneys Function: Provides padding, insulates, stores energy Areolar Tissue Location: Under skin, in or around mucous membranes, around blood vessels and nerves Functions: provides padding, binds the outer layer to the muscles beneath. Adipose- nucleus, plasma membrane, fat vacuole, and reticular fibers

Dense Regular Connective Tissue Ex. Tendons and Ligaments Locations: Between skeletal muscles and skeleton; between bones or internal organs Functions: Provides firm attachment, conducts pull of muscles, reduces friction Fibroblast cells

Elastic Tissue Location: Between vertebrae of the spinal column; in blood vessel walls Functions: Stabilizes positions of vertebrae; cushions shocks Dominated by elastic fibers. Stabilizes the positions of the vertebrae of spinal column

Cartilage The matrix of cartilage is a firm gel that contains polysaccharide derivatives Chondrocytes- Cartilage cells, the only cells in the cartilage matrix Lacunae- Small chambers that cartilage cells occupy Cell islands=lacunae

Hyaline Cartilage Locations: Between tips of ribs and bones of sternum; supporting larynx, trachea, and bronchi Functions: Provides stiff but flexible support, reduces friction between bony surfaces Most common type of cartilage, Fibers are not in large bundles and do not stain darkly.

Elastic Cartilage Locations: In the ear and in the trachea Functions: Provides support, but tolerates distortion without damage and returns to original shape

Fibrous Cartilage Locations: Pads within knee joint; between pubic bones of pelvis; intervertebral discs Functions: Resists compression; prevents bone-to-bone contact; limits relative movement Little ground substance, matrix is dominated by densely interwoven collagen fibers, extremely durable and tough.