Review for anatomy

Review for anatomy - Basement Membrane Anchors epithelium...

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Basement Membrane – Anchors epithelium to the underlying connective tissue GENERAL CHARACTERISTICS OF EPITHELIUM Display Polarity – displaying sidedness (nucleus present on one end of cells) o Bottom = Basal, Top = Apical o Refer to figure 4.5 of text book (T to B: nucleus, endoplasmic reticulum, golgi apparatus, secretory vesicles, microvilli) Epithelium is Avascular – contain NO blood vessels Regenerate very quickly – able to recover rapidly after being damaged o Over %90 of cancers are epithelial in origin because they divide so rapidly o Carcinoma – uncontrollable growth of epithelial cells FUNCTIONS OF EPITHELIAL CELLS 1. Absorption – selective permeability of certain nutrients, ions, etc…… a. Important in small Intestines (absorbing food, nutrients, etc….) 2. Secretion – Epithelial cells produce their own products which they secrete in order for the body to utilize a. Important in glands 3. Excretion and Filtration – two processes are closely coupled, take waste or damaged products from inside of body to outside of body (EXCRETION), epithelial cell selectively allows certain molecules to stay in or stay our (FILTRATION) a. Important in the kidneys 4. Protection – lines surfaces of body cavities, linings, and coverings. Present to help protect from outside environment and to separate the internal order of the body. CLASSIFICATION OF EPITHELIUM 1. By number of layers – Simple vs. Stratified a. Simple – Only one layer of Epithelium Cells b. Stratified – Multiple layers of Epithelium Cells 2. By shape – Squamous, Cuboidal, or Columnar a. Squamous – flattened and spindly b. Cuboidal – Cube like shape where it is as tall as it is wide c. Columnar – Taller then it is wide SIMPLE EPITHELIUM Simple Squamous – One layer of very flat cells in which every epithelial cell is in contact with basement membrane. Thinnest kind of epithelium. Capillaries, air sacs in lungs, Simple Cuboidal – single layer of cells that are a little thicker then Squamous, both do not offer a whole lot of protection. Used for secretion, found in most secretory glands Simple Columnar – Single layer of fairly tall cells, 1. Contain Microvilli (which increase surface area). This helps with absorption, mainly found in digestive tract.
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2. Shaped like a wine glass or goblet (narrow basal side with a wide apical cells), this helps with the secretion of mucus and also secretion in respiratory tract. 3. These cells also contain cilia (made up of tubulin). Used to propel the environment around the cells so nutrients can pass by and be absorbed. Present in oviduct. Pseudostratified (fake stratified) – Cells of varying heights, types, and sizes which give it the appearance of being stratified but is actually simple 1. Ciliated – Repiratory tract, STRATIFIED EPITHELIUM Stratified Squamous – many thin cell layers built one on top of the other. These are the thickest, most resistant type of epithelium. Although a single layer is not very strong, after the layers build up
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Review for anatomy - Basement Membrane Anchors epithelium...

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