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Neuronal Communication

Maddi Thompson Neuroscience Inglés 42 fichas

Fichas del conjunto (42)

  1. 1Electrical potential (voltage)Force exerted on charged particle
    Greater electrical potential = greater the current
  2. 2Equilibrium potentialvoltage required to balance ionic gradient
  3. 3Electrical conductanceRelative ability an electrical charge has to migrate from one point to another
  4. 4Leakage ion channelsAllows ions to pass through channel ANYTIME, irrespective of membrane potential
  5. 5Voltage gated channelsChannels only open in response to specific voltage
  6. 6Ligand gated channelsonly open in response to binding of ligand to its receptor
  7. 7Resting potential-70mV
    Normal, unstilted conditions
    Neurons always working to maintain resting potential - requires energy
    Leaky channels release K+
    Na+/K+ pump active - removes 3 Na+, takes in 2 K+ (ATP)
  8. 8Voltage gated K+ channelsClosed during resting potential
    Only open when membrane potential reaches +40mV
    Allow K+ out of axon
  9. 9Voltage gated Na+ channelsClosed during resting potential
    Only open when membrane potential reaches -50mV (threshold)
    Allow Na+ into axon
  10. 10Threshold value-50mV
    Stimulates an AP
    Na+ move into
  11. 11DepolarisationAn action potential
    Opening of voltage gated Na+ channels
    Makes inside of axon less -ive
    Continues until membrane potential reaches +40mV
  12. 12RepolarisationClosing of Na+ channels
    Opening of voltage gated K+ channels
    Outflow of K+, membrane potential lowered
  13. 13Hyperpolarisation= too far
    Too many K+ leave cell
    Na+/K+ pump actively pumps Na+ out and K+ in to restore normal intracellular environment
  14. 14Absolute refractory periodTime from depolarisation to repolarisation
    Na+ channels are in an inactivated state and can't reopen again until resting potential restored
  15. 15Propagation of signal from one neuron to anotherNo resistance loss because post-synaptic AP just as large as pre-synaptic AP
    All APs are all-or-nothing
    All neurons have to reach threshold to conduct an AP
  16. 16Synapse= where neurons communicate with each other
    Uses chemical messengers called neurotransmitters
    Integration of signals determines the action of the post-synaptic neuron
    - mainly excitatory = AP
    - mainly inhibitory = no AP
  17. 17Neurotransmission across synapseAP triggers opening of Ca2+ voltage gated channels - influx of Ca2+ at pre-synaptic membrane
    Vesicles filled NTs fuse with pre-synaptic membrane and triggers exocytosis
    NTs diffuse across synaptic cleft
    bind to receptors on post-synaptic cell
  18. 18Graded potentialChange in membrane potential of post-synaptic cell
    Local change in membrane potential
    Sum of the individual actions of the ligand gated channels - if large enough = AP
  19. 19Excitatory synapseReceptor binding causes post-synaptic potential to be more +ive
    Depolarisation
    If it get above threshold, AP results
    EPSP
  20. 20Inhibitory synapseReceptor binding causes post-synaptic membrane to be more -ive
    Hyperpolarisation
    Less likely to reach threshold so no AP
    IPSP
  21. 21Excitatory NTse.g. glutamate
    Make inside of neutrons LESS NEG.
    Closer to threshold (-50mV)
    Increased likelihood of an AP occurring
  22. 22Inhibitory NTse.g. GABA
    Makes inside of neuron MORE NEGATIVE
    Further away from threshold - hyperpolarised
    Less likely for an AP to occur
  23. 23EPSPSynaptic potential that makes a post-synaptic neuron more likely to generate an AP
  24. 24Spatial summationWhen there are enough synapses close together to produce an AP in the next neuron
  25. 25Temporal summationWhen the post-synaptic membrane is depolarised in rapid succession
  26. 26IPSPSynaptic potential that makes a post-synaptic neuron less likely to generate an AP
  27. 27Fates of NTs1. bind to receptors on post-synaptic cell
    2. destroyed by enzymes
    3. re-uptake by pre-synaptic terminal
    4. diffuse away
    5. taken up by glia (astrocytes)
  28. 28Synaptic delay~0.5 sec delay b/w arrival of AP at axon terminal and action at synapse
    If a signal is being sent through many neurons, this delay can add up
    -> use electrical synapse
  29. 29Electrical synapsesWhere neutrons directly connect via gap junctions
    Extremely rare: some brain sites, eye and PNS ganglia
    APs ALWAYS TRANSMITTED TO POST-SYNAPTIC CELL
    Efficient/fast but not versatile
    Used for reflexes
  30. 30Criteria for a molecule to be a NT1. must be synthesised and stored in the pre-synaptic neuron
    2. must be released by the pre-synaptic axon terminal upon stimulation
    3. when experimentally applied, must produce a response in the post-synaptic cell that mimics the response produced by the release of NT from the pre-synaptic neuron
  31. 31Agonist NTstimulates the receptor
  32. 32Antagonist NTblocks/inhibits the receptor
  33. 33Amino acid NTse.g. glutamate (+), GABA (-), glycine (-)
    Fast neurotransmitters
  34. 34Classical/amine NTse.g. ACh (+/-), serotonin (-), NA (+)
    Mainly slow neurotransmission
  35. 35Neuropeptide NTse.g. substance P, opiods
    Slow neurotransmission
  36. 36Other Itse.g. nitric oxide, hydrogen sulfide, CO
    Not packaged in pre-synaptic cell for release
    Still released in activity dependent manner
  37. 37Dale's PrincipleA neuron has a single NT
    Classifies neutrons into groups of NT types
    1. cholinergic (ACh)
    2. catacholminergic (dopamine)
    3. amino acidergic (GABAergic)
    Most neurons release a single a.acid or amine NT
    BUT many peptide neurons violate Dale's Principle - co-transmitters
  38. 38Peptide NT synthesis and storage1. precursor peptide synthesised in rER
    2. precursor protein split in Golgi to form active neurotransmitter
    3. secretory vesicles containing peptide bud off Golgi body
    4. secretory granules are transported down the axon (anterograde transport) to terminal where peptide is stored
  39. 39Amine and amino acid NT synthesis and storage1. enzymes convert precursor molecules into NT molecules in the cytosol
    2. transport proteins loss the NT molecules into synaptic vesicles in the terminal where they are stored
  40. 40Ionotrophic NTFASTER - directly bind to and opens ion channel
    Ligand-gated
    Open and close in response to NT binding
    No second messengers
    Excitatory: glutamate, inhibitory: GABA
  41. 41Metabolic NTSLOWER - acts via secondary messengers to activate effector proteins
    Sense ligand-binding to receptor and activates a signaling cascade within the cell
    G-COUPLED PROTEIN
    Neither excitatory or inhibitory; but regulate the activity of excitatory and inhibitory neurotransmitters
    2 major families of 2nd messengers:
    1.Cyclic AMP (cAMP)
    2. Inositol triphosphate (IP3)
  42. 42—

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Neuroscience Fichas sobre Neuronal Communication, creado por Maddi Thompson el 09/11/2017.
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Maddi Thompson
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