Chapter 5 (1)

• There are 4 types of tissues: epithelial, connective, muscle, and nervous.
• An Organ is a structure with discrete boundaries that is composed of two or more tissue types. Histology (microscopic anatomy) is the study of tissues and how they are arranged into organs.
• Matrix is extracellular material and it is made up of Fibrous proteins and Clear gel called ground substance that is also known as tissue fluid, extracellular fluid (ECF), interstitial fluid, or tissue gel.
• A fertilized egg becomes an embryo with 3 layers of embryonic tissues; Ectoderm (outer), Mesoderm (middle), and Endoderm (inner). The mesoderm becomes gelatinous tissue called mesenchyme.
• The ectoderm gives rise to skin, hair, nails, teeth, glands, and sensory receptors. It forms the central nervous system and peripheral nerves.
• The endoderm gives rise to the lining of the digestive tract, lungs, liver, pancreas, thyroid, parathyroids, thymus, and urinary bladder.
• Mesenchyme gives rise to bone, cartilage, blood vessels, fat cells, tendons, ligaments, and dermis.
• Tissue sections include; Longitudinal section (l.s.)(divides into front and back), Cross section (c.s. or x.s.) or transverse section (t.s.)(divides into up and down), and Oblique section (divides into a slanted version of cross section).
• When interpreting Tissue Sections smearing means rubbing the tissue across the slide(e.g blood) and spreading means laying down the tissue on the slide (e.g areolar tissue)
• Epithelia are closely packed cells that cover body surfaces and line body cavities, constitute most glands, and are Avascular(but are usually nourished by underlying connective tissue). Epithlia covers body surfaces and lines body cavities.
• Epithelial Tissues have basement membranes which are layers between an epithelium and underlying connective tissue. e.g. Collagen, reticular proteins, glycoproteins. They anchor the epithelium to the connective tissue below it.
• Basal surface—cell surface facing the basement membrane. Apical surface—cell surface that faces away from the basement membrane. Lateral surface—cell surface between the basal and apical surface, “sidewall”.
• Epithelial Tissue has 2 types: Simple epithelia and Stratified epithelia.
• Simple Epithelia has 4 types; Simple squamous (thin, scaly cells). Simple cuboidal (square or round cells). Simple columnar (tall, narrow cells that have goblet cells). and Pseudostratified columnar (has goblet cells too).
• Goblet cells are wine-glass-shaped mucus-secreting cells.
• Stratified Epithelia has four types; Stratified squamous(the most widespread epithelium in the body and can either be Keratinized(e.g palms or soles of feet) or Nonkeratinized(e.g. vagina)), Stratified cuboidal (likes to gather itself in a circle), Stratified columnar (rare), and Urothelium(the transitional epithelium).