Connective Tissues

Connective Tissues

1. Basic elements

   • Basic Fxn= connect or support
   • Found inside, supporting organs
   • cells scattered about in matrix
   • vascularity varies
   • look at substances between the cells
   • fibroblasts produce the matrix
   • matrix= fibers & ground substance
   • most common fiber is COLLAGEN, ELASTIC & RETICULAR fibers also seen
   • ground substance is an amorphous, gel-like substance

2. 5 True Types

   • loose/ areolar
     • loosely organized
     • abundant blood vessels
     • seemingly empty space
     • underlies ALL epithelia
       • connects skin to deep tissues
         • in serous membranes, between muscles, passageways for nerves & blood vessels
     • photo
   • adipose
     • empty looking cells w/ thin margins
       • nucleus pressed against cell membrane
     • energy storage
       • insulation, cushioning
       • subcut. fat & organ packing
       • brown fat (hibernating animals) produces heat
     • photo
   • reticular
     • mesh of reticular fibers & fibroblasts
       • forms supportive stroma (framework) for lympathic organs
     • lymph nodes, spleen, thymus, bone marrow
     • photo
   • dense regular
     • densely packed, parallel collagen fibers
       • compressed fibroblast nuclei
       • elastic tissue/ fibers wavy sheets
     • tendons (attach muscles to bones)
       • ligaments (hold bones together)
     • photo
   • dense irregular
     • densely packed, randomly arranged
       • collagen fibers & few visible cells
       • withstands unpredictable stress
     • deeper layer of skin
       • capsules around organs
     • photo

3. 4 Structural

   • Hyaline
     • clear, glassy microscopic appearance
       • fine collagen fibers
       • usually covered by perichondrium
         • lacunae, chondrocytes
     • articular cartilage, costal cartilage, trachea, larynx, fetal skeleton
       • eases joint mvmnt, holds airway open, moves vocal cords
       • endochondral bone formation
     • photo
   • Elastic
     • containing elastic fibers
       • covered w/ perichondrium
     • flexible, elastic support
       • external ear & epiglottis
     • photo
   • Fibrocartilage
     • large, coarse bundles of collagen fibers
       • NEVER has perichondrium
     • resists compression & absorbs shock
       • pubic symphysis, menisci, intervertebral discs
     • photo
   • Bone
     • arranged in cyliners surrounding central canals that run through long bone
       • blood vessels & nerves travel through central canal
         • bone matrix deposited in concentric lamella
           • lamella - onionlike layers around each central canal
     • osteocytes live in lacunae
     • photo

4. Blood

   • fluid connective tissue (formed in bone marrow)
     • transports cells & dissolved matter from place to place
   • plasma= blood's liquid ground substance
     • erythrocytes= red blood cells
       • transport O2 & CO2
       • leukocytes= white blood celles
         • defense against infection & other diseases
         • thrombocytes= platelets (cell fragments)
           • clotting & other mechanisms