Histology lab.docx - HISTOLOGY CELLS TISSUES AND ORGANS Readings chapter 5 tissues organs and organ systems chapter 7 p 156 157 In this lab we will

Histology lab.docx - HISTOLOGY CELLS TISSUES AND ORGANS...

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HISTOLOGY: CELLS, TISSUES AND ORGANS Readings: chapter 5 tissues, organs, and organ systems, chapter 7 p. 156 - 157 In this lab we will examine in detail the tissues and cell types we have been discussing in lecture. We also take a cursory look at organs, as a compilation of tissue types. Being animals, humans are multicellular and composed of many different cell types; over two hundred. The great majority of cells are assembled in coherent groupings bound together by cell junctions and extra-cellular matrix to form tissues. As discussed in class each tissue is specialized for a particular function and each has a distinctive pattern of organization. Organs are body structures composed of several different tissues grouped together to form a structural and functional unit. Organs are then grouped together to form organ systems. Remember when examining slides of tissues you must think in three dimensions although the preparations may appear two dimensional. Remember that cells are small. Most of your observations should be made under high power, ask for assistance if you want to use oil immersion. Also keep in mind that many of the preparations are slides of organs and there will be several tissue types on a single slide. Make sure you are looking at the right one. You will need to ‘scan’ the slide to find the right tissue type. Ask for help if you are not certain. There are four basic tissues: epithelium , connective , muscular and nervous . 1: EPITHELIAL TISSUE Generally speaking, epithelia form coverings (the outermost layer of the skin) and linings (single innermost layer of the intestine). Most of these tissues may be categorized by the number of layers of cells and by cell shape . A single layer of cells is referred to as a simple epithelium. A stratified epithelium is made up of more than one layer of cells. The cell shapes may be squamous (flattened) cuboidal (cube-shaped) or columnar (tall with a basally-located nucleus). Epithelia that are stratified are differentiated based on the shape of cells of the outermost layer, i.e., stratified squamous epithelium. Some epithelia may appear stratified but actually are made up of a single layer of cells and are called pseudostratified. Basement membrane - At the boundary between epithelial tissue and the underlying tissues is a supporting non-cellular structure called the basement membrane. It is composed of collagen-type filaments and glycoprotein and is secreted by the epithelial cells themselves. This is not to be confused with the cell or plasma membrane. Be able to distinguish between the basement membrane and cell membrane. Exercise: Identify four kinds of epithelial tissue. There are two epithelial slides, one is ‘Epithelium composite sec.’ which has three preps on it. They are simple columnar, simple cuboidal and stratified squamous. Make sure you can identify all three. The other slide shows simple squamous epithelium; it can be found lining the bowman’s capsule of the kidney. It will appear as a circular space in the tissue. Be able to identify the cells types and the basement membrane.
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  • Fall '10
  • EricAlcorn

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