CBIO 2200 1nd Edition Lecture 8 Outline of Last Lecture I. Classes of Epithelium and Cell ShapeII. Simple EpitheliaIII. Stratified EpitheliaIV. Connective Tissue FunctionsV. Adipose TissueVI. CartilageOutline of Current Lecture I. Tissue GrowthII. Tissue DevelopmentIII. Stem CellsIV. Tissue RepairV. Tissue Shrinkage (Atrophy) and DeathVI. Programmed Tissue DeathVII. Tissue EngineeringChapter 6I. Integumentary SystemII. Functions of skinIII. The Skin and Subcutaneous TissueThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.IV. Layers of EpidermisCurrent LectureI. Tissue Growtha. Increasing the number of cells or the existing cells grow largerb. Hyperplasia – increase in cell numberc. Hypertrophy – enlargement of the cells that are already thered. Neoplasia – development of a tumor; (neoplasm)i. Benign: don’t grow or grow slowlyii. Malignant: bad tumors; metastatic cancer (when cancer cells break off from primary tumor and start growing somewhere else)II. Tissue Developmenta. Differentiation – undergo changes within certain limitsb. Cells don’t become specific types until some time during fetus development; almost never change cell type once they are specifiedc. Metaplasia:i. Changing from one type of mature tissue to anotherii. Ex: pseudo-stratified column epithelium  stratified squamous epithelium1. Seen when there is exposure to some sort of environmental hazard2. Does not occur under natural/normal circumstancesIII. Stem Cellsa. Stem cells – undifferentiated cells; hasn’t become a certain type yetb. Embryonic stem cellsi. Totipotent – “all powerful” have potential to become any type of cellii. Pluripotent – appear once you get to blastocyst stage; can become many things but are slightly more specific than totipotent c. Adult stem cellsi. Undifferentiated cells in tissues of adults1. Some are multi-potent: in bone marrow, and can become whatever it needs to2. But most are uni-potent: e.g. in muscles, cells can only be muscle cellsIV. Tissue Repaira. Damaged tissue can be repaired in two ways:i. Regeneration: restoration of normal function of the cell (e.g. skin, liver)1. Regeneration occurs in healing cuts in skin; sets up clots and stops the bleeding; blood vessels and capillaries regenerate and form granulation tissue2. Bottom layer of epidermis undergo mitosis and regenerate3. Get some scar tissue in dermis and some regenerationii. Fibrosis: replacement of normal tissue with scar tissue, but does not restore normal function (what happens with heart attacks); most organs undergo this type of repairV. Tissue Shrinkage (Atrophy) and Deatha. Atrophyi. Senile atrophy – shrinkage due to agingii. Disuse atrophy – shrinkage from lack of use (someone in wheel chair)b. Necrosis – traumatic tissue deathi. Infarction – tissue death as a result of a cut off or complete lack of blood supplyii. Gangrene– result of insufficient or lack of blood supply1. Dry gangrenea. Decubitus ulcer – bed sore or pressure sore2. Gas gangrene a. Anaerobic bacterial infection; smells horrible3. Amputate limbs with gangrene because it will spread otherwiseVI. Programmed Tissue Deatha. Apoptosis: programmed cell death; occurs in many of our organs and stem cells replenish the dead cells in organb. Phagocytized by macrophages to get rid of dead cellsc. Built in “suicide program” not fully understoodi. One proposed mechanism: Fas-mediated ii. Fas activates endonucleases that chop up DNA and proteases that destroyproteinsVII. Tissue Engineeringa. Tissue engineering: artificial production of tissueb. Skin grafts already availablei. Human outer ear grown on back of mouse, to use for aesthetic reasonsii. Made a nude mouse so that it’s immune system would not reject the ear because of the foreign stem cells (can replace ears, and skin; can’t replacelimbs or hearts or anything like that, but it is being worked on)Chapter 6 – The Integumentary SystemI. Integumentary systema. Composed of skin, glands, hair, and nailsb. Dermatology: study of skin and skin disordersc. Largest organ and most vulnerable due to exposure to external environmentII. Functions of Skina. Resist trauma and infectioni. Keratin: protein in top layer of epidermis; helps resist against micro-organisms ii. Acid mantle: pH of skin is low (4-6) which resists micro-organismsiii. This is why it’s important to keep cuts coveredb. Vitamin D synthesis: involved in first step of vitamin D synthesis; convert vitamin D from inactive to active form c. Sensation: pain and touch receptors that give us information about our surroundingsd. Thermoregulation: vasodilation/vasoconstrictione. Nonverbal communicationf. Transdermal absorption: rely on the ability of some drugs to be absorbed through our skin (e.g. nicotine patches)III. The Skin and Subcutaneous Tissuea. 1-2mm thickb. Two layersi. Epidermis1. Stratified squamous epithelium2. Keratinized & non-keratinized3. Lacks blood vesselsii. Dermis1. Dense irregular connective tissueiii. Hypodermis1. Where we find large amount of adipose tissue and blood vessels2. Hypodermic needle: called this because it goes down to the hypodermis to reach blood vesselsc. Thick skin: palms of hands and soles of feeti. Contain sweat glandsii. No hair folliclesiii. No sebaceous (oil) glandsd. Thin skin: everywhere elsei. Contain sweat glandsii. Contain hair folliclesiii. Contain sebaceous glandsIV. Layers of Epidermis (KNOW)a. Stratum basale: i. Contains stem cells that give rise to keratinocytesii. Highly mitoticb. Stratum spinosum: i. Keratiniocytes will start to produce keratinii. Contain keratin filamentsiii. Contains dendritic cells (immune cells)c. Stratum granulosumi. Keratin filaments have become keratohyalin granulesd. Stratum lucidumi. Only found in thick skinii. Keratohyalin granules become eleidone. Stratum corneumi. Contain mature keratinf. Epidemolytic hyperkeratosis: cause by keratin clumping together (not flat)i. Causes UV damageii. Causes water