Unit 2 - Tissues

Nota:

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

Nota:

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

Nota:

• 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

   Nota:

   • -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

   Nota:

   • -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

   Nota:

   • -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

   Nota:

   • -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

   Nota:

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

   Nota:

   • -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)

   Nota:

   • -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

   Nota:

   • -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

Nota:

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

1. fibroblast

   Nota:

   • produce collagen and elastic fibers
   1. macrophage

      Nota:

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

         Nota:

         • may release heparin and histamine

1. collagen fibers

   Nota:

   • have a great tensile strength
   1. elastic fibers

      Nota:

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

         Nota:

         • are fine collagen fibers

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

         Nota:

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

            Nota:

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

               Nota:

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

         Nota:

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

            Nota:

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

               Nota:

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

      Nota:

      • -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

         Nota:

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

            Nota:

            • -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