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Chapter 4

Chapter 4 - Histology.docx

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NUR 0012
Jake Dechant

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Fall 2013 Nur 0012 Chapter 4: Histology 1. What are the major characteristics of epithelial tissue? 2. Know the structure, functions, and locations of the epithelial tissues we discussed in class (squamous, cuboidal, columnar, transitional, pseudostratified). Know examples of  Simple squamous, Simple cuboidal, Simple columnar, Pseudostratified  Stratified squamous, Stratified cuboidal, Transitional 3. Know what functions simple and stratified epithelium serve in the body. 4. Name the 3 characteristics of all connective tissues  The cell types found in different connective tissues.  Know the three types of proteins found in connective tissue.  Know the different ground substances we discussed. 5. Know the structure, function and location of the different types of fibrous connective tissues. Know examples of  The loose connective tissues – adipose, areolar  The dense connective tissues – regular and irregular. 6. Know the different types of cartilage and what their structure, functions, and locations are.  Hyaline, elastic, and fibrocartilage  Cartilages are avascular  Know the purpose of Proteoglycans (hyaluronic acid, chondroitins) 7. Know the basic properties of bone and blood, and how all connective tissues are related. 8. Know the basic properties of both muscle and nervous tissue. 9. The three embryonic tissues and what they become. 10. The three epithelial membranes: mucous, serous, and cutaneous.  Think of where they are found. 11. Tissue Repair – Go over the 3 steps from my powerpoints. 1 Chapter 4: Histology I. Introduction  Tissues are composed of groups of specialized cells working together to perform specific functions.  Tissues are grouped into 4 categories Epithelial, Connective, Muscular, and Nervous.  Structure and function of tissues are closely related.  All Tissues arise from 3 primary germ layers in the developing embryo 1. Ectoderm – Epidermis and nervous system 2. Mesoderm – Muscle, bone, blood 3. Endoderm – Linings of digestive and respiratory tracts. Sectioning Longtitudinal: down the middle in half Cross Section: across, horizontal, luman: inside of cut Oblique: cut through at an odd angle II. Epithelial : has basement membrane: attaches epithelium to underlying tissue, thin layer of connective tissue glues epithelia tissue to another type of tissue Tight junctions keep it together Usually have free surface: exposed side A. Characteristics 1. Cellularity – very cellular, easy to distinguish between cells, very close to one another, like a quilt 2. Special cell contacts –supported by connective tissue 3. Polarity –  Free surface  Basement Membrane  Basal lamina 4. Supported by connective tissue – 5. Avascular but innervated – don’t have good blood supply, nerve endings throughout  All gases and nutrients carried in the blood must reach the cells by diffusing across the basement membrane.  In cells with many layers, the most active cells are nearest the basement membrane. 6. Regeneration – replace itself every 1-2 days deep layers 7. Where it’s found – stomach, digestive tract, mouth, olfactory epithelium (between the eyebrows), covers surfaces, skin, outside of tubing, can form glands when clumped together B. Classification of Epithelium 1. Classification based on number of cell layers 2 Fall 2013 Nur 0012  Simple - one cell layer, with each cell extending from basement membrane to free surface.  Stratified - more than one layer of cells with only one layer that is adjacent to the basement membrane  Pseudostratified - all cells are attached to basement membrane, but only some of the cells reach the free surface, and the folding of the others gives the appearance of stratification.  Transitional - a special type of stratified epithelium found only in the bladder, and ureters. 2. Classification based on cell shape  Squamous – flat, or sheet-like, thin  Cuboidal - cube-like, same height and width. Rounded edged squares  Columnar - tall and thin., nucleus at bottom,  * hexagonal most surface area* C. Functions of Epithelium 1. Based on cell layers Simple - found in organs whose principle functions are:  diffusion, filtration, secretion, absorption  Since simple is only one cell layer thick it is ideally adapted to areas in which substances must be able to move easily across cell membranes. Stratified - found in areas where protection is important  Stratified is well adapted to protection because as outer layers are damaged, new layers are being produced to replace it. 2. Based on Cell Shape  Squamous - are thin and flat and therefore allow substances to diffuse through them or act as filters.  Cuboidal or Columnar - are generally cells that secrete or absorb substances because they have a greater cytoplasmic volume than squamous cells. D. Types of Epithelia 1. Simple Simple Squamous: has to be thin so things can be diffused easily Structure - flat or oval with central nucleus. Location - places with little wear and tear and also in places where substances are diffused and filtered. Function - diffusion, filtration, secretion Body – alveoli, kidney capillaries, lining of heart and blood vessels ( when torn, causes blood clotting) Simple Cuboidal: often form tubes or ducts Structure - cube shaped with a central nucleus. Location - in tubules where they can reabsorb substances. Function - mainly absorption, active transport, secretion Body – kidney tubules, liver, thyroid, 3 Simple Columnar Structure - nucleus near bottom of column shaped cells. Location - inside lining of digestive tract, also contain goblet cells. Function - secretion of mucous, absorption. Body – begin in stomach, line digestive tract Pseudostratified: not multiple layers, all attached to basement membrabe, all different lengths Structure - all cells touch basement membrane but not all reach the free surface. Location - respiratory tract Function - specialized goblet cells release mucous that coat passageways. Body - lower respiratory tract 2. Stratified Stratified Squamous : cells get flatter as you move closer to surface, layers darker are more active Structure - many layers with outermost layer being flat and scale – like. Underlying layers are more cuboidal or columnar. Location - anywhere the outer layers can be abraded and generally wherever protection is needed. Function - protection against abrasion. In epidermis the keratin also acts as a waterproofing agent to fight water loss. Body – epidermis,  Keratin impregnantes into cells Nonkeratinized wet stratified, lines esophagus, retum, vaginal v. keratinized: dry Stratified Cuboidal - rare Structure - Cuboidal cells, but in layers. Location - wherever protection is needed. Function - protection and secretion. Body – sweat glands, ovarian follicles( secretes estrogen and progesteron) , Stratified Columnar - rare Structure - layers of columns - only outer layer is columnar. Location- male urethra. Function - protection and secretions. Body - Transitional 4 or 5 layers of cubes Structure - looks like stacks of cuboidal cells when in relaxed state, layers closest to apical surface can distend as bladder fills. Location - bladder, urethra, ureters Function - allows stretching of urinary bladder as it fills. Body - bladder, urethra E. Glands and membranes formed by epithelial cells in clumps 4 Fall 2013 Nur 0012 1. Endocrine - Have no ducts. Ducts were separated during development. Secrete hormones directly into blo
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