Unit 2 - Tissues

Annotations:

• Close space between cells by fusing cell membranes Ex. Cells that line the small intestine

Annotations:

• Bind cells by forming “spot welds” between cell membranes Ex. Cells of the outer skin layer

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• Form tubular channels between cells that allow the exchange of substances Ex. Muscle cells of the heart and digestive tract

1. cancer cells secrete a substance that dissolves the basement membrane, enabling the cells to invade other tissue layers (metastasis)
   1. cancer cells also produce fewer adhesion proteins (help cells to “stick” together) which allows them to spread into surrounding tissues.

1. simple squamous

   Annotations:

   • -one thin layer of flat cells (easily damaged) -diffusion (gas exchange in lungs), filtration (in kidney), secretion (glands) -alveoli of the lungs, kidney glomeruli, lining of the heart, blood vessels and lymphatic vessels, lining of the ventral body cavities.
2. stratified squamous

   Annotations:

   • -several layers of cells, top layer is flattened (squamous), thickest layer of epithelial tissue, can be keratinized (contains the protein keratin) or nonkeratinized. -protection keratinized: epidermis -nonkeratinized: mouth, esophagus, tongue, vagina
3. simple cuboidal

   Annotations:

   • -one layer of cube shaped cells (1 round nucleus) -secretion and absorption of substances (ex. to give urine its final composition, it moves substances in and out of the kidney tubule) -small glands, kidney tubules, ovary surface
4. simple columnar

   Annotations:

   • -one layer of elongated cells (having one oval nucleus), ciliated or nonciliated (contains microvilli) -absorption & secretion -nonciliated: mainly in the lining of the digestive tract (absorption) and lining the ducts of some glands (secretions) -ciliated: small bronchi, the uterine tubes, part of the uterus (secretions)
5. glandular
6. stratified cuboidal

   Annotations:

   • -several layers of cube shaped cells -protection -largest ducts of sweat glands, mammary glands, salivary glands
7. stratified columnar

   Annotations:

   • -several layers, top layer contains elongated cells -protection and secretion -very rare in the body - it lines part of the urethra, large ducts of some glands, portion of the conjunctiva of the eye
8. simple psuedotratified (pseudostratified columnar)

   Annotations:

   • -one layer of cells that are attached to the basement membrane, cells at different heights, nuclei at different heights, ciliated or nonciliated -secretion and movement of mucus -ciliated in respiratory tract (bronchi)
9. transitional

   Annotations:

   • -several layers of cells that can be stretched. will look like a stratified squamous epithelium if it is stretched or a stratified cuboidal epithelium if it is unstretched -allows for distention of urinary organs -bladder, ureters, part of urethra

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• consists of fibers and a ground substance (gel-like material)

1. fibroblast

   Annotations:

   • produce collagen and elastic fibers
   1. macrophage

      Annotations:

      • are phagocytes (“eat cells”)
      1. mast cell

         Annotations:

         • may release heparin and histamine

1. collagen fibers

   Annotations:

   • have a great tensile strength
   1. elastic fibers

      Annotations:

      • are composed of elastin and are stretchy
      1. reticular fibers

         Annotations:

         • are fine collagen fibers

1. connective tissue proper
   1. loose connective tissue
      1. areolar

         Annotations:

         • -forms thin membranes between organs and binds them together -found beneath the skin and surrounds organs
         1. adipose

            Annotations:

            • -stores fat, cushions, and insulates -found beneath the skin; in certain abdominal membranes; around the kidneys, heart, various joints
            1. reticular

               Annotations:

               • -thin branched reticular fibers -supports the walls of the liver and spleen
   2. dense connective tissue
      1. dense regular

         Annotations:

         • strong collagen fibers that bind structures as parts of tendons and ligaments
         1. dense irregular

            Annotations:

            • thicker, randomly distributed collagen fibers and is found in the dermis
            1. elastic

               Annotations:

               • elastic fibers that make up hollow internal organs like the lungs and blood vessels
2. special connective tissues
   1. cartiledge

      Annotations:

      • -provides support -consists of fibers and a gel-like substances -lacks a direct blood supply, so it is slow to heal -found at the ends of various bones; in the ear; in the larynx; and in the pads between the bones of the spinal column, pelvic girdle, and knees
      1. bone

         Annotations:

         • -matrix consists of mineral salts and collagen -compact & spongy bones. -heals rapidly
         1. blood

            Annotations:

            • -composed of cells suspended in fluid -produced in the tissue of hollow parts of certain bones

1. Skeletal
   1. Smooth
      1. Cardiac

1. coordinate, regulate, and integrate many body functions