Chapter 23 ID Terms

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Chapter 23 ID Terms
2015-05-03 23:12:13
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  1. epidermis
    forms the outer covering, creating a waterproof barrier that is self-repairing and continually renewed; it is the fundamental, quintessential component of the skin
  2. dermis
    Thick layer of connective tissue, which includes the tough collagen-rich dermis (from which leather is made) and the underlying fatty subcutaneous layer or hypodermis
  3. Interfollicular epidermis
    Regions of less specialized, more or less flat epithelium covering the body surface between the hair follicles and other appendagesStructure: multilayered (stratified) epithelium composed of keratinocytes
  4. Desmosomes
    Site of anchorage for thick tufts of keratin filaments; located in prickle cellsDesmosomes
  5. granular cell layer
    The cells are sealed together to form a waterproof barrierThis layer marks the boundary between the inner, metabolically active strata and the outermost layer of the epidermis, consisting of dead cells whose intracellular organelles have disappeared
  6. terminal cell differentiation
    • The process in which a precursor cell acquires
    • its final specialized characteristics and usually permanently stops dividing;
    • the whole program is initiated in the basal layer; it is here that the fates of
    • the cells are decided
  7. stem cells
    • cells that have the following criteria:
    • 1)      It is not itself terminally differentiated (not the end of the pathway)
    • 2)      It can divide without limit (or at least for the lifetime of the animal)
    • 3)      When it divides, each daughter has a choice. It can remain a stem cell or terminally differentiate
    • Stem cells must be able to divide. However, they don’t have to divide rapidly. 
  8. absorptive cells (brush border/ enterocytes)
    Absorptive cells (brush-border cells_)have densely packd microvilli on their exposed suraces to increase their active surface area for the uptake of nutrients. They both absorn buntrients and secrete hydrolytic enzymes that perform some of the final steps of extracellular digestion, breaking down food molecules in preparation for transport across the plasma membrane
  9. goblet cells
    secrete mucus
  10. paneth cells
    Form part of the innate immune defense system and secrete cryptidins—proteins of the defensing family hta tkill bacteria
  11. Enteroendocrine cells
    more than 15 different subtypes) secrete serotonin and peptide hormones, such as CCK, that act on neurons and other cell types in the gut wall and regulate the growth proliferation and digestive activities of cells of the gut and other tissues. CCK for example is released in enteroendocrine cells in response to the presence of nutrients int eh gut and binds to receptors on nearby sensory nerve endings, which relay a signal to the brain to stop you feeling hungry after you’ve eaten enough
  12. APC
    • Codes for a protein that prevents inappropriate
    • activation of the Wnt signaling pathway, so that loss of APC is presumed to
    • mimic the effect of continual exposure to the Wnt signal
  13. Stem cell niche
    Special environment provided for the stem cells; the crypt provides it for the gut stem cells
  14. hepatocytes
    Cells in the liver that derive from the primitive gut epithelium that are arranged in interconnected sheets and cords, with blood-filled spaces called sinusoids running between them; they synthesize, degrade, and store a vast number of substance; secrete most of the protein found in blood plasma
  15. hepatocyte growth factor
    Stimulates hepatocytes to divide in culture, and its production increases steeply in response to liver damage
  16. Endothelial cells
    Form the linings fo the hblood vessels; have a remarkable capacity to adjust their number and arrangement ot suit local requirements; they create an adaptable life-support system, extending by cell migration into almost every region of the bdoy
  17. granulocytes
    Contain numerous lysosomes and secretory vesicles and are subdivided into three classes according to morphology and staining properties of these organelles
  18. hematopoiesis
    Blood cell formation, which involves complex controls, which regulate the production of each type of blood cell individually to meet changing needs; hematopoietic tissues do not appear orderly and many have a nomadic lifestyle that makes them more accessible to experimental study
  19. stromal cells
    Fat cells and other connective tissue cells, which produce a delicate supporting meshwork of collagen fibers and other ECM components
  20. Blood sinuses
    • The whole tissue is richly supplied with
    • thin-walled blood vessels into which the new blood cells are discharged
  21. Hemopoietic stem cell
    Remain in the marrow when mature and are very large with a highly polyploidy nucleus; normally lie close beside blood sinuses and extend processes through holes in the endothelial lining of these vessels
  22. Colony-stimulating factors
    Glycoproteins that circulate in the blood and act as hormones, while others act in the bone marrow either as secreted local mediators or as membrane-bound signals that act through cell-cell contact
  23. erythrocyte
    Most common type of cell in the blood (red blood cell); when mature, it is packed full of hemoglobin and contains hardly any of the usual cell organelles; cannot grow or divide de to lack of nucleus, ER, ribosomes, and mitochondria; have a limited life span and are phagocytosed and digested by macrophages when damaged
  24. erythropoietin
    Secreted when there is a lack of oxygen or shortage of erythrocytes; Stimulates production of more erythrocytes
  25. interleukin-3
    A CSF that promotes the survival and proliferation of the earlier erythroid progenitor cells; in its presence, such larger erythroid colonies develop from cultured bone marrow cells in a process requiring 7-10 days
  26. satellite cells
    If muscle is damaged or stimulated to grow, they are activated to proliferate, and their progeny can fuse to repair the damaged muscle or to allow muscle growth; the stem cells of adult skeletal muscle, normally held in reserve in a quiescent state but available when needed as a self-renewing source of terminally differentiated cells
  27. connective tissue cells
    Members are related and interconvertible; family includes fibrolasts, cartilate cells, and bone cells, all of which are specialized for the secretion of collagenous ECM and are jointly responsible for the architectural framework of the body; also includes fat cells and smooth muscle cells
  28. cartilage
    Structurally simple, consisting of cells of a single type—chondrocytes—embedded in a more or less uniform highly hydrated matrix consisting of proteoglycans and type II collagen
  29. Bone
    Dense and rigid; it grows by apposition—by deposition of additional matrix on free surfaces
  30. pericytes
    cells of the connective-tissue family, related to vascular smooth muscle cells, that wrap themselves around smallvessels.