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HSCI 100 (134)
Lecture 4

Week 4.docx

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Department
Health Sciences
Course Code
HSCI 100
Professor
Nienke Van Houten

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CHAPTER 19A: STEM CELLS STEM CELLS: - Unspecialized cells that divide continually to create a pool of undifferentiated cells for possible use - Categorized by degree of flexibility in developmental path o Multipotent: can specialize to be many types of cells o Unipotent: can specialize to be one type of cell o Totipotent:can specialize to be any cell type (e.g. fertilized egg) o Pluripotent: can specialize to be nearly every type of cell (in early embryo) SOURCES OF HUMAN STEM CELLS - Adult stem cells: unipotent & multipotent o More difficult to locate o In bone marrow, brain, skin, liver o Ready to generate new cells for repair/replace old o Identity will depend on extrinsic (niche) & intrinsic factors (gene expression program) o Difficult to work with & present in small amounts  E.g. bone marrow - Umbilical cord stem cells: multipotent o Treat leukemia o Stem cells on umbilical cord = immature. Less likely for body to reject o Easier to extract than from bone marrow o Less likely to carry infections o Can produce endless supply of blood cells - Embryonic stem cells: pluripotent o Can divide continually & specialize in nearly any cell type o UNUSED EMBRYOS FROM FERTILITY CLINICS  Blastocyst: sphere of cells containing cluster of 20-30 cells (inner cell mass) adhering to one side of sphere. Stem cells are main cell mass  Easy to harvest, divide for years, create stem cell line Somatic cell nuclear transfer (SCNT) - Nucleus from somatic body cell transferred to an egg from which the egg nucleus has been removed - Stimulated to begin embryonic development Therapeutic cloning – produce clone of “replacement cells” having same genetic makeup as given patient so that they could be used in patient’s medical therapy w/o concern of being rejected by immune system Reproductive cloning – production of new individual with a known genetic makeup Induced pluripotent stem cells - Creation of pluripotent stem cells w/o need to destroy embryo POTENTIAL USES FOR STEM CELLS - Replacement for damaged cells - Growing new organs – regenerative medicine o Coax stem cells to grow and fill in tissue scaffolds that were engineered in lab Describe possible therapeutic uses of stem cells Differentiate between embryonic & adult stem cells ADULT TISSUE STEM CELLS - Present in wide variety of adult tissues - Multipotent - Used to regrow new tissues ideally compatible - Identity will depend on extrinsic (niche) & intrinsic factors (gene expression program) - Difficult to work with & present in small amounts - E.g. bone marrow EMBRYONIC STEM CELLS - Pluripotent - In vitro can be guided to specific cell type Discuss the ethical and political controversy surrounding embryonic stem cell research - Removing stem cells destroys embryo, putting an end to its ability to become a fetus DISEASES THAT MAY BE TREATED WITH STEM CELLS - Test new drugs in vitro - Cell based therapies o Repair organs o Treat Alzheimer’s, spinal cord injury, stroke, burns, heart disease, diabetes, osteoarthritis, rheumatoid arthritis - To make treatments consistent we need to: o Proliferate extensively & generate sufficient quantities of tissue o Differentiate into the desired cell type o Survive in the recipient after transplant o Integrate into the surrounding tissue after transplant o Function appropriately for the duration of the recipient’s life o Avoid harming recipient in any way Embryonic stem cells – available in more quantity Stem cells differentiate because certain genes are turned on and off Controversy - Some people believe that an embryo is a human life and therefore should not be subjected to experimentation - Playing god - Concerns that stem cell will go to human cloning CHAPTER 4: BODY ORGANIZATION & HOMEOSTASIS Define a tissue, organ, organ system + give example Tissue: collection of cells of the same type that perform a common function - 1)*Connective - Functions: storage site for fat, immunity, protection and support for body and organs - Connective-tissue matrix has 3 protein fibers PRODUCED BY FIBROBLASTS: o Collagen fibers – strong + rope like, can withstand pulling o Elastic fibers – random coils and can stretch and recoil like a spring (skin,lungs,blood vessels) o Reticular fibers – thin strands of collagen that branch extensively forming interconnecting networks for supporting soft tissues (liver/spleen) o Fibrous/Connective tissue proper  Loose vs. dense  Both contain fibroblast cells with matrix of collagen & elastic fibers  E.g. loose – support epithelium & internal organs o Adipose tissue – where fat is stored, areolar connective tissue  E.g. dense – makes up ligaments, tendons, collagen fibers packed together o Supportive/specialized connective tissue  Cartilage - provides flexible support, cushions  Cells in chambers – lacunae  Matrix = solid but flexible  Low blood supply – heals slower than bone, lacks blood vessels and nerves  1. Hyaline cartilage – fine collagen fibres o Location: nose, end of long bones, fetal skeleton  2. Elastic cartilage – more elastic fibers than cartilage fibers o More flexible. Location – outer ear  3. Fibrocartilage – strong collagen fibers, @areas with high tension/pressure  Location – disks between vertebrae  Bone – provides support + protection by enclosing and levers for muscles to act on  Cells in chambers – lacunae  Matrix – solid+rigid, made of collagen (Flex) + calcium salt(rigid)  Vascularized  1. Compact – repeating circular units (osteons) containing hard matrix and living cells + blood vessels o Location – shafts of long bones  2. Spongy – open, latticework with irregular spaces surrounds bone marrow cavity o Location – ends of long bones CARTILAGE BONE Location of cells Lacunae Lacunae Density of matrix Solid but flexible Solid but rigid Composition of matrix Collagen and elastic fibers Collagen and calcium salts vasculature Low blood supply yes o Fluid – transports o2 and co2, nutrients, hormones, wastes, helps fight infections  Blood (SKIM)  Made of fluid matrix = plasma + formed ele
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