CBIO 2200 1nd Edition Lecture 8 Outline of Last Lecture I Classes of Epithelium and Cell Shape II Simple Epithelia III Stratified Epithelia IV Connective Tissue Functions V Adipose Tissue VI Cartilage Outline of Current Lecture I Tissue Growth II Tissue Development III Stem Cells IV Tissue Repair V Tissue Shrinkage Atrophy and Death VI Programmed Tissue Death VII Tissue Engineering Chapter 6 I Integumentary System II Functions of skin III The Skin and Subcutaneous Tissue These 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 Epidermis Current Lecture I II III IV Tissue Growth a Increasing the number of cells or the existing cells grow larger b Hyperplasia increase in cell number c Hypertrophy enlargement of the cells that are already there d Neoplasia development of a tumor neoplasm i Benign don t grow or grow slowly ii Malignant bad tumors metastatic cancer when cancer cells break off from primary tumor and start growing somewhere else Tissue Development a Differentiation undergo changes within certain limits b Cells don t become specific types until some time during fetus development almost never change cell type once they are specified c Metaplasia i Changing from one type of mature tissue to another ii Ex pseudo stratified column epithelium stratified squamous epithelium 1 Seen when there is exposure to some sort of environmental hazard 2 Does not occur under natural normal circumstances Stem Cells a Stem cells undifferentiated cells hasn t become a certain type yet b Embryonic stem cells i Totipotent all powerful have potential to become any type of cell ii Pluripotent appear once you get to blastocyst stage can become many things but are slightly more specific than totipotent c Adult stem cells i Undifferentiated cells in tissues of adults 1 Some are multi potent in bone marrow and can become whatever it needs to 2 But most are uni potent e g in muscles cells can only be muscle cells Tissue Repair a 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 tissue 2 Bottom layer of epidermis undergo mitosis and regenerate 3 Get some scar tissue in dermis and some regeneration V VI VII ii 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 repair Tissue Shrinkage Atrophy and Death a Atrophy i Senile atrophy shrinkage due to aging ii Disuse atrophy shrinkage from lack of use someone in wheel chair b Necrosis traumatic tissue death i Infarction tissue death as a result of a cut off or complete lack of blood supply ii Gangrene result of insufficient or lack of blood supply 1 Dry gangrene a Decubitus ulcer bed sore or pressure sore 2 Gas gangrene a Anaerobic bacterial infection smells horrible 3 Amputate limbs with gangrene because it will spread otherwise Programmed Tissue Death a Apoptosis programmed cell death occurs in many of our organs and stem cells replenish the dead cells in organ b Phagocytized by macrophages to get rid of dead cells c Built in suicide program not fully understood i One proposed mechanism Fas mediated ii Fas activates endonucleases that chop up DNA and proteases that destroy proteins Tissue Engineering a Tissue engineering artificial production of tissue b Skin grafts already available i Human outer ear grown on back of mouse to use for aesthetic reasons ii 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 replace limbs or hearts or anything like that but it is being worked on Chapter 6 The Integumentary System I II Integumentary system a Composed of skin glands hair and nails b Dermatology study of skin and skin disorders c Largest organ and most vulnerable due to exposure to external environment Functions of Skin a Resist trauma and infection i Keratin protein in top layer of epidermis helps resist against microorganisms ii Acid mantle pH of skin is low 4 6 which resists micro organisms iii This is why it s important to keep cuts covered III IV b 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 surroundings d Thermoregulation vasodilation vasoconstriction e Nonverbal communication f Transdermal absorption rely on the ability of some drugs to be absorbed through our skin e g nicotine patches The Skin and Subcutaneous Tissue a 1 2mm thick b Two layers i Epidermis 1 Stratified squamous epithelium 2 Keratinized non keratinized 3 Lacks blood vessels ii Dermis 1 Dense irregular connective tissue iii Hypodermis 1 Where we find large amount of adipose tissue and blood vessels 2 Hypodermic needle called this because it goes down to the hypodermis to reach blood vessels c Thick skin palms of hands and soles of feet i Contain sweat glands ii No hair follicles iii No sebaceous oil glands d Thin skin everywhere else i Contain sweat glands ii Contain hair follicles iii Contain sebaceous glands Layers of Epidermis KNOW a Stratum basale i Contains stem cells that give rise to keratinocytes ii Highly mitotic b Stratum spinosum i Keratiniocytes will start to produce keratin ii Contain keratin filaments iii Contains dendritic cells immune cells c Stratum granulosum i Keratin filaments have become keratohyalin granules d Stratum lucidum i Only found in thick skin ii Keratohyalin granules become eleidon e Stratum corneum i Contain mature keratin f Epidemolytic hyperkeratosis cause by keratin clumping together not flat i Causes UV damage ii Causes water loss