Organization of Tissue Connective Tissue

1. Organization of TissueConnective Tissue

2. Definition of Connective Tissue • Used to connect…. • Examples include basement membrane, bone, fat and blood • Uses include: • Support • Structure • Storage of energy • And transport • Composed of three parts • Specialized cells • Fibers (protein) matrix • Ground substance (fluid)

4. Specific Functions • Through out body, but never exposed • Highly vascular • Contain sensory receptors • Establishing structural framework • Transporting fluids and dissolved materials • Protecting delicate organs • Support, surround and interconnect other tissues • Store energy as triglycerides • Defense from invading microorganisms

5. Classification of Connective Tissues • Connective Tissue Proper • Many types of cells, fibers in syrupy ground substance • Loose CT (adipose) • Dense CT (tendon) • Fluid Connective Tissue • Distinct populations of cells in watery matrix with dissolved proteins • Blood and lymph • Supporting Connective Tissue • Less cells, more fibers • Cartilage and bone

6. Connective Tissue Proper Cell Types • Fibroblasts • Always present • Most abundant • Makes many proteins • Fibrocytes • #2 abundance • Source of fibers • Collagen • Reticular • Elastic • Adipocytes • Fat cells • Mesenchymal cells • Stem cells; differentiate • Found in embryonic CT • Macrophages • Amoeboid (engulf or eat) • Immunity • Mast cells • Mobile • Near blood vessels • Make histamine and heparin • Lymphocytes • Produce antibodies • Microphages • Also phagocytic • Melanocytes • Make melanin

7. Fibers • Collagen • Long, straight, unbranched • Bundle of proteins • Flexible but strong • Found in tendons (muscle to bone) and ligaments (bone to bone) • Stronger than steel; more likely to break bone than tendon ! • Reticular • Thinner, interwoven, network • Resist force in many directions • Stabilize positions of organs and vessels against changing positions and gravity • Elastic • Elastin • Wavy • Return to position after stretching

8. Loose CT • “packing” between organs • Cushion and stabilize • Three types • Areolar • Spaces • Least specialized • Resilient • Padding • “pinched” skin • Adipose • Padding • Insulation • White fat – • Brown fat – vascular and lots mitochondria; metabolism • Reticular • Spleen, liver, lymph nodes

9. Dense CT • Mostly fibers • Lots of collagenous fibers • Divided into dense regular and dense irregular • Regular • Tendons and ligaments • Irregular • Surround flat muscles, bones and organs • Also found in the cavities of the joints

10. Fluid Connective Tissue • Blood • Watery, fluid matrix known as plasma • Distinct populations of cells (RBC, white and platelets) • Dissolved proteins • Lymph • Forms as interstitial fluid • Enters lymphatic vessels • Eventually returned to large veins near the heart • Process (vessels to interstitial to lymph and back to vessels) is necessary for immunity and homeostasis – blood volume

11. Supporting CT • Cartilage • Chondrocytes in lacunae with matrix and fibers • Three types (pg 129) • Hyaline ; stiff but flexible, decrease friction – ribs, joints, larynx, nose • Elastic; tolerates distortion – ear, epiglottis • Fibrocartilage; resists compression – knee, intervertebral discs • Bone • Calcium salts make up matrix • Collagen fibers • Blood vessels with lacunae that contain osteocytes

12. Membranes • Barrier • Epithelia + CT • 4 types • Mucous Membranes • Line digestive, respiratory and reproductive • Moist, low friction, lubrication • Serous • Sealed • Pericardium, viscera, thin, permeable, constantly diffusing fluids • Cutaneous • Thicker, waterproof and usually dry • Synovial • At joints • Lubrication between bones at articulations