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Tissues Part B Connective Tissues • 12 different tissues – – – – – – – – – – – Embryonic Alveolar Adipose Reticular Dense regular Dense irregular Hyaline cartilage Elastic Cartilage Fibrocartilage Osseous Blood Common Characteristics of Connective Tissues 1. All originate from mesenchyme tissue in the embryo 2. Can be avascular or vasculated; cartilage is avascular while loose connective tissue is vascular 3. Extracellular matrix of nonliving chemicals plus the cells Characteristics of Connective Tissue 1. 2. 3. 4. 5. 6. 7. Weight bearing (bone) Withstand great amount of tension Endure abuse of physical trauma and abrasion Binds cells together as a group Can form “ropes” to hold muscle to bone Insulates organs as packing Permits transportation of cells and chemicals from one set of cells to another through ground substance Connective Tissue – Physical Characteristics • Contains cells that are widely spaced apart • Located in a loose or dense structure that can consist of one or both of the following – Fibers – Ground substance – a semisolid gel of water, glycoproteins (sugar-protein molecule that is gluey), adhesion proteins and other chemicals to hold everything together and provide a transportation medium Connective Tissue • Connective tissue supports epithelium – Reticular lamina under the basal lamina contains collagen – Both basal lamina and reticular lamina form the “basement membrane” – Basement membrane protects epithelium from stretching out of shape or tearing; define epithelial boundary Vocabulary • Lamina - layer; a thin, flat plate of a larger composite structure. • Reticular - Resembling a net in form; netlike. • Lucida – clear • Desmosomes – proteins that “spot weld” cells together or to other tissues Terminology • - blast – cells that form tissues or other cells • - cyte – cell • -clast – break down tissues • Chondro – cartilage • Osteo - bone • Lacunae - A cavity, space, or depression, especially in a bone, containing cartilage or bone cells. Epithelial cells Basement membrane • Basement membrane is the clear region between the two lines at the point of the green arrow Ground Substance The amorphous intercellular material in which the cells and fibers of connective tissue are embedded; composed of proteoglycans, plasma constituents, metabolites, water, and ions present between cells and fibers. Also called matrix. Ground Substance with fibers and cells Ground Substance The amorphous intercellular material in which the cells and fibers of connective tissue are embedded; composed of proteoglycans, plasma constituents, metabolites, water, and ions present between cells and fibers. Also called matrix. Fibers • Collagen Fibers – – – – Made of collagen Crosslinked Highly tensile Resist longitudinal stress • Stand up and do a side bend – When fresh are a glistening white; called white fibers • Elastic fibers – Branching networks – Made of elastin, which is rubbery and stretchy – Good recoil to original shape • Pull skin out from back of hand – does it “snap back”? – Found in skin, blood vessels and lungs – When fresh are yellow: called yellow fibers Collagen fibers (thicker) Elastic fibers (darker blues and blacks) Fibers • Reticular fibers – fine collagenous fibers – highly branched network (hence reticula; means “maze” or “pattern”) – surround blood vessels, support soft organ tissue – Seen between different tissues; form a fuzzy “nest” that allows for give with the organs Embryonic or Mesenchyme Tissue • Found in embryo • Gives rise to all other connective tissues • Contains lots of ground substance, mesenchymal cells that give rise to all four types of connective tissue What gives rise to what? Mesenchymal tissue Fibroblasts Chondroblasts Connective tissue proper Cartilage Loose Dense areolar regular adipose irregular reticular elastic Hyaline Osteoblast Compact bone Spongy bone Fibrocartilage Elastic cartilage Hematopoietic stem cell Blood cells Erythrocytes (RBC) Leucocytes (WBC) Thrombocytes (platelets) Areolar Tissue (Loose) • Lots of ground substance (clear) • Thin elastic and thick collagen fibers • Various cells (fibroblasts, macrophages, mast cells, white blood cells) Adipose Tissues (loose) • Aka ‘fat cells’ Brown fat Brown vs. White • Brown fat - A dark-colored, mitochondrionrich adipose tissue in many mammals that generates heat to regulate body temperature, especially in hibernating animals. • White/yellow fat - contains stored cellular fat. Good for cushioning bones, insulation, gives “shape” to human females. Reticular Tissue (Loose) • Reticular fibers, ground substance, reticular cells, macrophages, mast cells • Supports other cells like an internal skeleton Dense regular (Dense connective) • Tissues are fairly straight and run in one plane • Interspersed with various cells • Notice how evenly the cells are lined up • Found in tendons and ligaments, where regularity is a must Dense Irregular (Dense connective) • Notice how irregular or “all over” this tissue is • Contains fibroblasts and collagen fibers • Found in skin dermis and around some organs that move multidirectionally Elastic (Dense connective) • Consists of ground substance and elastic fibers • Where stretch is needed • Under the skin, surrounding aorta and arteries, veins, lungs, elastic cartilage and other parts Osseous (Compact and Spongy) • Compact bone forms the outer edge of the bones, making a hard outer coating that gives strength • Spongy (cancellous) bone is found in the long bones and in the sternum; it provides a supporting internal scaffold while helping make bones lighter Cartilage • • • • Three types of tissues Hyaline Elastic Fibrocartilage Hyaline cartilage • Firm matrix • Collagen fibers present, but imperceptible • Chondroblasts produce matrix • Chondrocytes (mature chondroblasts) lie in lacunae • Long bone covers; costal cartilage; cartilage of nose, trachea, larynx • Is the embryonic skeleton constituent Elastic Cartilage • Similar to hyaline, with prominent elastic tissue • Maintains shape with greater flexibility • External ear and epiglottis Fibrocartilage • Less firm matrix, preponderance of thick collagen fibers in a regular pattern • Ability to absorb compressive shock • Intervertebral discs, symphysis pubis, discs of knee joints Fibrocartilage – Symphysis pubis Fibrocartilage Squishy center to allow “give” and absorb shock Location of fibrocartilage Blood • Blood is a connective tissue • Aids in oxygen transport, immune response, blood clotting Macrophages • Purple cell surrounded by red blood cells • Stained – usually clear or buffy colored • Active part of immune system • Looks for intruders to “eat” and tell rest of immune system about Mast Cells • Highly granular • Located in matrix • Contain histamine (an inflammatory chemical) and heparin (a anti-clotting chemical) • Open up when you are wounded to cause swelling of the tissue Plasma cells • “B” white blood cells that create antibodies against previously contracted infections • Antibodies attack invading organisms to immobilize until macrophage can show up to eat the invader Plasma cells Erythrocytes • Red blood cells • Biconcave, permits O2/CO2 perfusion across membrane