Phys Ch5

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Author:
bkheath
ID:
103740
Filename:
Phys Ch5
Updated:
2011-09-30 23:21:25
Tags:
Physiology
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Description:
Cell Signaling
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  1. Type of cell-to-cell communication which is common in smooth and cardiac muscle
    Gap junctions
  2. Substance that has a signaling function
    Chemical messenger
  3. Molec that binds to a biomolec
    Ligand
  4. Chemical that signals & triggers a cellular response by binding to receptor on the cell
    Agonist
  5. Chemical which binds to cell receptor, basically blocking it from other chemicals binding, resulting in no cellular signal/response
    Antagonist
  6. Chemical that serves to signal nearby cell (ex: histamine responsible for inflammation response)
    Paracrine chemical msngrs
  7. Chemical that signals the same cell that secreted it (source cell & target cell are the same)
    Autocrine chem msgnrs
  8. Chem msgnr produced by neurons & released into the ECF of synaptic cleft (short distance)
    Neurotransmitters
  9. Chem msgnr produced by endocrine cells & secreted into blood via interstitial fluid
    Hormones
  10. Chem msngr produced by neurons and secreted into blood via interstitial fluid (ex: antidiuretic hormone (ADH), oxytocin)
    Neurohormones
  11. Chem msgnr which cannot easily pass cell membranes so may need pump or channel; often on cell mem
    Lipophobic Ligands
  12. General action of lipophobic ligands (2)
    • Enzyme activation
    • Membrane permeability chgs
  13. Chem msngr which easily crosses cell mem; receptor located w/in cell
    Lipophilic Ligands
  14. General action of lipophilic ligands
    Gene activation
  15. Ligands move to their target cells by:
    • Diffusion through interstitial fluid
    • Blood-borne transport
  16. In blood-borne transport, lipophobic ligands ________ and lipophilic ligands ________
    • Dissolve in plasma
    • Bind to carrier protein
  17. Messenger Half-life
    time for a chem to decrease concentration in half (half of msngrs are still signaling)
  18. How a chemical signal is translated into a cell action:
    Msngr binds to receptor
    Binding results in cell response
    Signal transduction
  19. Strength of binding
    affinity
  20. Location of binding:
    Lipophobic ligands:
    Lipophilic ligands:
    • Cell mem
    • W/in cell
  21. When receptor number decreases on target cell; may result from excess msngr
    Results in lower sensitivity to msngr b/c of tolerance
    Down-regulation
  22. When receptor number increases on target cell, causing increase of sensitivity to msngr; may result from too little msngr
    Up-regulation
  23. 2 mechanisms of signal transduction
    • 1. Intracellular-mediated responses: responses w/in the cell
    • 2. Membrane-bound receptor-mediated responses
  24. 3 types membrane-bound receptors
    • Channel-linked receptors
    • Enzyme-linked receptors
    • G protein-linked receptors
  25. What kind of ligands are involved in intracellular-mediated response & why
    Lipophilic ligands, b/c they can easily pass thru cell mem, to receptors inside (in cytosol or nucleus)
  26. How does cell respond to a lipophilic ligand coming in and binding to a receptor?
    Gene activation: gene is made via transcription to make whatever specific protein is needed
  27. How do the membrane-bound receptors of the target cell respond to ligand binding? (2 general ways)
    • Mvmt of ions
    • Phosphorylation of enzymes (activation or inactivation of cell signaling pathways)
  28. Type of receptor in which the receptor and channel are the same protein; binding of ligand causes channel to open or close; chg in transport of ions thru channel causes response
    (Binding on outside causes chg on inside)
    Channel-linked receptor
  29. Type of receptor in which the receptor and enzyme are the same protein; the ligand binding activates the enzyme which causes response
    (enzyme is "w/in" protein)
    (picture cell mem protein w/ receptor end on outside, enzyme end on opposite side inside gets chgd at the "active site")
    Enzyme-linked receptor
  30. Type of receptor which involves a regulatory protein that links a receptor to other mem proteins, including ion channels and amplifier enzymes
    G protein-linked receptor
  31. Why are G protein-linked channels called slow ligand-gated channels?
    The receptor and channel are diff proteins (which are linked by G protein)
  32. Type of receptor which is activated by binding of ligand, and then goes on to activate a channel protein, causing target response b/c of chg in transport of ions thru channel (this chgs cell mem permeability b/c ions can now enter or not)
    G protein-linked channel
  33. How do G proteins-linked receptors activate second messengers?
    When ligand binds to G protein-linked receptor, the G protein activates an amplifier enzyme, which activates second msgnr production, which amplifies the ligand's signal
  34. cAMP is a type of _____ that signals that the cell is out of energy
    second msngr
  35. A second msngr is a type of ____
    enzyme

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