Connective Tissues

111. Connective Tissues A. General Characteristics: most abundant tissue in the body, gives support to the body and it's organs and binds/attaches tissues and body structures together. B. Structural Makeup and Functions (1) All connective tissues are made up of specialized living cells, suspended in a nonliving material called a matrix (ground substance). (2) Matrix substance or ground substance can be watery, gelatinous, fiber-laden or hardened/calcified, or combinations therein depending on the type of connective tissue. (3) Matrix/Ground Substance is composed of three classes of molecules: (a) Glycosaminoglycan (GAG)- a long polysaccharide made of amino acids/uronic acid that is able to absorb/hold water. Examples: heparin, chondroitin sulfate and hyaluronic acid, (b) Proteoglycans- gigantic molecules with a central core of proteins with bristle-like outgrowths of (GAG). They form thick colloids and structural bonds, (c) Adhesive glycoproteins- protein-carbohydrate complexes that bind plasma membrane proteins to collagen and proteoglycans outside the cell, holding tissues together. (4) Three types of nonliving fibers, which are produced by cells called fibroblasts are also found in various within a given connective tissue matrix: Collagenous (collagen protein, white, wide, strong), Elastic (elastin protein, yellow, thin, with elasticity), and Reticular (made of collagen but are thin, inelastic, and branch/overlap to form a network or reticulum to support soft organs (liver/spleen). (5) Connective tissue gives the body shape and form. (6) Connective tissue binds various tissues together and provides a packing material between body parts, stores fat, and aids in tissue repair. (7) The ground substance of loose connective tissue provides a pathway for blood vessels and nerves, nutrients, gases, and wastes are transported from capillaries to cells (and back) via the ground substance. 111. Connective Tissues (C) Connective Tissue Classifications  (1) Embryonic Connective Tissue (a) Mesenchyme Tisue- Is unspecialized, packing, wrapping, and supportive tissue of early embryonic/fetal life. All types of adult connective tissue cells derive from the star shape embryonic/fetal mesenchyme cell. (b) Mucoid Tissue (Wharton's Jelly)- Appears temporarily in the normal, development of connective tissue and is also found in the umbilical cord. (2) Connective Tissue Proper (a) Adipose Tissue- made of cells called adipocytes, with some reticular fibers and small amounts of collagenous/elastic fibers. (i) Stores fat droplets (energy reserves) which displace the nucleus to the lateral side of the cell. (ii) Gives minimal protection to organs it is packed around (iii) Insulates the body from excessive heat loss (iv) Located beneath skin/scalp, around the heart, kidneys etc., in bone marrow, in the breast/buttocks (b) Loose (Areolar) Connective Tissue-