Unit Two: Tissues

Annotations:

• Close space between cells by fusing cell membranes 

Annotations:

• Bind cells by forming "spot welds" between membranes 

Annotations:

• Form tubular channels between cells to allow for the exhchange of substances 

1. Found in the brain, spinal cord, and peripheral nerves
   1. Neurons are highly specialized

      Annotations:

      • -sense changes in surroundings  -have dendrites, which receive sensory info and transmit the message as an electrical signal to the axon..sends message to the next neuron or to muscles or glands  -function: coordinate, regulate, and integrate 

1. Neuroglia
   1. Supporting cells of the nervous tissue
      1. Some bind and support nervous tissue, some carry phagocytosis

         Annotations:

         • Phagocytes protect nervous tissue by engulfing cellular debris, waste, and foreign material 
         1. Some connect neurons to blood vessels, and some are involved w/ cell-to-cell communication

1. Muscle cells are also called...

   Annotations:

   • Cell fibers 
2. Skeletal muscle makes up....% of body weight and smooth and cardiac about...

   Annotations:

   • 40%, 10%
   1. Three types of muscle tissue
      1. Skeletal

         Annotations:

         • Function: move body parts, facial expressions, writing, talking, singing, chewing, swallowing, and breathing 
         1. Muscles that contain skeletal muscle tissue are usually attached to bones
            1. Each cell has many nuclei -> multinucleate
         2. voluntary muscle tissue
            1. Contract when stimulated by a nerve cell, then relaxed when it is no long stimulated
         3. The cells are long, threadlike

            Annotations:

            • About 40 mm in length and less than .1 mm in width 
            1. Contain striations

               Annotations:

               • Alternating light and dark cross-markings
      2. Smooth
         1. No striations
         2. Cells are short and spindle shaped
            1. Found in the walls of hollow internal organs

               Annotations:

               • Stomach, intestines, bladder, uterus, blood vessels 
         3. One central nucleus per cell
            1. Involuntary control

               Annotations:

               • Moves food through digestive tract, constricts blood vessels, and empties the bladder 
      3. Cardiac
         1. One nucleus per cell
         2. Involuntary control

            Annotations:

            • Pumps blood through the heart and into the blood vessels
         3. Cells are striated, branched, joined end-to-end and interconnected
            1. Specialized intercellular junction -> intercalated disc

               Annotations:

               • Connection b/w cardiac muscle cells 
         4. Function w/o nervous stim.

1. Classified according to cell shape and the number of cell layers
   1. Simple Squamous

      Annotations:

      • -One layer of flat cells -Diffusion, filtration, secretion  -alveoli of lungs, ithe kidney, the lining of the heart, blood vessels, and ventral cavities 
   2. Simple Cuboidal

      Annotations:

      • -One layer of cuboidal cells -Secretion and absorption -Small glands, kidney tubules, and ovary surface
   3. Simple Columnar

      Annotations:

      • -one layer of columnar cells -Non ciliated: absorption of digested food, secretion of mucus  -digestive track -Ciliated: secretion, moving mucus  -small bronchi, uterus
   4. Pseudostraified Columnar

      Annotations:

      • -One layer of cells, all on basal membrane  -Secretion and propulsion of mucus -Nonciliated: male urethra and ducts of large glands -Ciliated: found on trachea, primary bronchi, and upper respiratory 
   5. Stratified Squamous

      Annotations:

      • E-has several layers, with a surface of flat cells -protection..may contain keratin that repels bacteria  Keratinized: epidermis of skin Non-keratinized: lines wet surfaces, such as mouth, esophagus, tongue 
   6. Stratified Cuboidal

      Annotations:

      • -Several layers, but the surface is cuboidal  -Protection  -largest ducts of sweat glands, mammary glands, salivary glands
   7. Stratified Columnar

      Annotations:

      • -Several layers, with columnar surface -Protection and secretion -Very rare: lines parts of the urethra, large ducts of glands, conjunctiva of eye
   8. Transitional

      Annotations:

      • -shape at surface us transitory..will look like stratified squamous when stretched, stratified cuboidal when not.  -distension of urinary organ  -on surface of stretchy organs, like the bladder and uterus. 
   9. Glandular

1. Basement membrane
   1. Anchors epithelium to connective tissue
   2. Cancer cells dissolve the membrane or produce fewer adhesion proteins

1. Cell types
   1. Fibroblasts

      Annotations:

      • Produce collagens and elastic fibers 
   2. Macrophages

      Annotations:

      • Are phagocytes (eat cells)
   3. Mast cells

      Annotations:

      • Release heparin and histamine 
2. Tissue fibers
   1. Collagen

      Annotations:

      • Great tensile strength
   2. Elastic

      Annotations:

      • Composed of elastin, are stretchy 
   3. Reticular

      Annotations:

      • Fine collagen fibers 

1. Categories of Tissue
   1. Loose
      1. Areolar

         Annotations:

         • Description: membranes between organs that bind them together  Location: Beneath skin and surrounds organs
      2. Adipose

         Annotations:

         • Function: stores fat, cushions, insulates Location: beneath skin, in certain abdominal membranes, and around kidneys, heart, and various joints
      3. Reticular

         Annotations:

         • Description: thin branched reticular fibers Function: supports the walls of the liver and spleen
   2. Dense
      1. Regular

         Annotations:

         • Description: strong collagen fibers that bind structures as parts of tendons and ligaments 
      2. Irregular

         Annotations:

         • Description: thicker, randomly distributed collagen fibers  Location: found on dermis 
      3. Elastic

         Annotations:

         • Description: make up hollow internal organs  Location: line the lungs and blood vessels
   3. Specialized
      1. Cartilage

         Annotations:

         • Description: provides support -fibers and a gel-like substance  -lacks direct blood supply, slow to heal Location: ends of various bones, in ear, in the larynx, in b/w spinal column, pelvic girdle, knees
      2. Bone

         Annotations:

         • -Matrix consists of mineral salts and collagen -Compact and spongy bones -Heals rapidly 
      3. Blood

         Annotations:

         • Description: composed of cells suspended in fluid Location: produced in tissue of hollow parts of certain bones 

1. Consists of fibers and a ground substance (gel-like)