bio 224 theme 7

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Scottygo
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239137
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bio 224 theme 7
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2013-10-06 23:56:51
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bio 224 theme 7
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  1. Convergence of input
    presynaptic inputs to postsynaptic neuron
  2. divergence of output
    presynaptic outputs to postsynaptic neurons
  3. three different types of synapses
    • electrical
    • chemical
    • neuromuscular
  4. neuromuscular synapse
    • •When a motor neuron reaches a skeletal muscle, it divides into many terminal branches, each of which forms a neuromuscular junction with a single muscle cell;
    • •The presynaptic neuron releases a neurotransmitter that binds to receptors located in a muscle cell
  5. motor unit
    • -made up of a motor neuron and the skeletal muscle fibers innervated by that axon.
    • - Groups of motor units often work together to coordinate the contractions of a single muscle
  6. Two types of presynaptic input
    Excitatory-Brings membrane closer to threshold(EPSP)

    inhibitory -Takes membrane farther from threshold potential (usually hyperpolarizes)(IPSP)
  7. when does a synaptic signal end?
    when neurotransmitter broken down by enzymes or taken back into presynaptic cell for reuse.
  8. Synaptic integration
    –Integration of multiple inputs on multiple dendrites
  9. Spatial summation
    • -When two or more EPSPs or IPSPs are generated at one time along different regions of the dendrites and cell body
    • -does not cross threshold
  10. Temporal summation
    • –Two or more EPSPs arrive at same location in quick succession.
    • -Crosses threshold
  11. Epsp-Ipsp cancellation
    simultaneous activation of both inputs resulting in no potential change due to cancellation
  12. Neurotransmitters
    • -Endogenous chemicals that transmit signals from a neuron to a target cell across a synapse
    • -Categorized by size, structure and function–All nervous systems operate with combined excitatory and inhibitory actions of neurotransmitters
  13. What causes release of neurotransmitters
    Release of neurotransmitters usually follows an action potential, but may also follow graded electrical potentials
  14. How to neurotransmitters act in the absence of electrical stimulation?
    Neurotransmitters are secreted at a low level baseline
  15. kinesin
    -purpose
    -structure
    • -walks along microtubule carrying vesicles or other cell structures
    • -two -helical segments used to hold cargo
    • -two Feet comprised of -helices and -strands
  16. How a Kinesin Molecule Walks
    •The feet end has reactive groups that “walk” along a microtubule or microfilament by making an attachment, forcefully swiveling a short distance, and then releasing
  17. Dynein
    A molecular motor used to carry debris from synapse back to cell across a microtubule for degradation in lysosome
  18. three aminos that convert to neurotransmitters
    tryptophan to serotonin

    Histidine to Histamine

    tyrosine to dopamine to norepinephrine to Epinephrine
  19. Neuropeptides
    -Small protein-like molecules (peptides) secreted by neurons as signaling molecules that influence the NS

    involved in: analgesia, reward, food intake, metabolism, reproduction,social behaviors, learning and memory
  20. Neuropeptides vs Peptide Hormones
    -secreted from...
    • •In some cases peptides function in the periphery as hormones also have neuronal functions as neuropeptides
    • •The distinction between neuropeptide and peptide hormone has to do with the cell types that release and respond to the molecule
    • –Neuropeptides are secreted from neuronal cells
    • –peptide hormones are secreted from neuroendocrine cells
  21. Enzymes that synthesize neuropeptides and peptide hormones
    • –Prohormone convertases
    • –Carboxypeptidases that selectively cleave the peptide precursor at specific processing sites to generate the bioactive peptides.
  22. •Electrochemical gradient:
    Combined effect of electrical and chemical gradients.

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