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2014-01-30 22:29:45
Chapter Four

Neural Conduction and Synaptic Transmission
Show Answers:

  1. What is the charge inside of the neuron compared to the outside and what is this state called ?
    Resting Membrane Potential: Inside the neuron is NEGATIVE (-70mV)
  2. What are the four ions that contribute to the neuron and where are they placed ?
    • Sodium (Na+) Outside
    • Chloride (Cl-) Outside
    • Potassium (K+) Inside
    • Negative Proteins Inside (these are always stuck within the neuron)
  3. What factors contribute to EVEN distribution wihtin the ionic basis of the resting potential ?
    • Random Motion: particles that are in areas of high concentration want to move to areas with low concentration
    • Electrostatic Pressure: like forces repel, opposites attract
  4. What factors contribute to UNEVEN distribution within the ionic basis of the resting potential ?
    • Selective Permeability: Membrane allows selective ions in
    • Sodium-Potassium Pumps: Constantly working (3 NA+ out / 2 K+ in)
  5. The Sodium-Potassium Pumps are a what process ?
    Active Process
  6. Where does the Postsynaptic Potentials (PSP) occur ?
    • Integrated near the Axon Hillox
    • Summation occurs over time and space (adding or combining a number of individual signals into one overall signal)
  7. The Postsynaptic Potentials (PSPs) cause ?
    • Depolarization: making the membrane potential LESS negative (-70 to -67 mV). This is EXCITATORY (more likely a neuron will fire) (EPSP)
    • Hyperpolarization: making the membrane potential MORE negative (-70 to -73 mV). This is INHIBITORY (less likely a neuron will fire) (IPSP)
  8. EPSP and IPSP are ? (Like a rock thrown in the pond with ripples, need more then one small pebble)
    • Graded: the greater the stimulus, the greater the response
    • Decremental: they get smaller as they travel
  9. To fire an Action Potential there needs to be a reach of ?
    • Threshold of Activation (-65 mV)
    • More than one EPSP
  10. The Action Potential is a what name ?
    • All-or-None: when threshold is reached the neuron 'fires' and the Action Potential either occurs or does not
    • When threshold is reached, voltage-activated ion channels are opened (-70 to +50 mV)
  11. What are the two aspects of the Refractory Periods (x1000/sec) ?
    • Absolute: IMPOSSIBLE to initiate another action potential
    • Relative: HARDER to initiate another action potential (High/Supra can cause action potential)
  12. What is the faster conduction than in unmyelinated axons ?
    • Saltatory Conduction: Passive conduction along each myelin segment to next node of Ranvier
    • New action potential generated at each node
  13. What does the Nurotransmitters release when Calcium comes into the cell and the NTs are dumped ?
  14. What are the two classes of Receptors for a given NT ?
    • Ionotropic Receptors: open and close ion channels
    • Metabotropic Receptors: effect function of neuron & open and close channels
  15. What happens within the Ionotrpoic Receptor ?
    • NT binds->associated ion channel opens or closes->PSP
    • NA+ channels open->NA+in->EPSP
    • K+ channels opened->K+ out->IPSP
  16. What happens within the Metabotropic Receptors ?
    NT binds->G protein breaks away->Ion channel opened/closed & 2nd messenger synthesized
  17. What are two ways that the activity in the synaptic cleft is turned off ?
    • Reuptake: scoop up and recycle NT
    • Enzymatic Degradation: NT broken down by enzymes
  18. What are the seven NT and what are their functions ?
    • Serotonin: Mood, temperature regulation
    • Dopamine: Pleasure, reward, motor movement
    • Acetylcholine: Memory, muscle contraction
    • Anandamido: Pain reduction, increase appetite
    • Norepinephrin: Stress hormone, mood, sleep, brain arousal
    • GABA: Main inhibitory NT
    • Glutamate: Main excitory NT, sensory neuron
  19. What are the two classes of NT molecules ?
    • Small: Synthesized in the terminal button and packaged in synaptic vesicles
    • Large: Assembled in the cell body, packaged in vesicles, and then transported to the axon terminal
  20. What are considered the Small-Molecule NT ?
    • Amino Acids
    • Monoamines:DA, NE, EPI, Seretonin
    • Acetylcholine (Ach)
    • Unconventional NT (soluble gases, endocannabinoids)
  21. What Amino Acid NT are Excitatroy and Inhibitory ?
    • Glutamate: Excitatory in CNS
    • GABA: Inhibitory in CNS
  22. What is the Monoamines ?
    • Synthesized from a single amino acid (Tyrosine OR tryptophan)
    • Effects tend to be diffuse
  23. What are the two procedures of Monoamines ?
    • Catecholamines: synthesized from tyrosine (Tyrosine->Dopamine->Norepinephrine->Epinephrine)
    • Indolamines: synthesized from tryptophan (milk, turkey) creates serotonin
  24. Where is Dophamin located and what does it involve ?
    • Basal Ganglia: involved in motor movement
    • Limbic System: involved in reward & pleasure
    • Frontal Lobe: involved in STM & planning
  25. What is the impact of Acetylcholine ?
    • Only NT released at neuromuscular junction (NMJ)
    • Can help with learning and memory
    • In Alzheimer's can be used during low stages to help
  26. What are the different effects on Synaptic Transmission ?
    • Agonists: Increase OR facilitate NT activity
    • Antagonists: Decrease OR inhibit NT activity
    • Drugs may alter NT activity at any point in its 'life cycle'
  27. What are some examples of Agonists drugs ?
    • Cocaine - Dopamine: Blocks reuptake- preventing the activity of the NT from being turned off
    • Benzodiazepines - GABA: binds to the GABA molecule and increases the binding of GABA (glue)
  28. What are some examples of Antagonist drugs ?
    • Atropine - ACH: Binds and blocks muscarinic receptors in CNS (metabotropic)
    • Botox - ACH: Blocks releach of Ach at nicotinic receptors at NMJ (ionotropic)