Doing Now

• Presynaptic Neuron

  1. Synthesizes neurotransmitters

  2. Stored in synaptic vesicles

  3. AP → voltage-gated Ca2+ channels open

  4. Ca2+ enters

  5. Some vesicles fuse

  6. Release neurotransmitters
• Neurotransmitters

  • Diffuse across synaptic cleft
  • Bond + activate specific postsynaptic receptors
• Postsynaptic Potentials

  • Change in membrane potential of postsynaptic cells
  • Triggered by ligand-gated ion channels
• Types of Postsynaptic Potentials

  • Excitatory Postsynaptic Potential (EPSP): depolarizes
  • Inhibitory Postsynaptic Potential (IPSP): Hyperpolarizes
• Summation of PSP:

  • Amount of EPSP or IPSP being transmitted
  • depends on #, distance, amount
  • stronger when closer to axon
  • Temporal and Spatial
• Temporal:

  • 2+ EPSP at 1 synapse
  • goes one after the other
  • stronger depolarization
• Spatial:

  • 2+ EPSP at different synapses
  • all go at the same time
  • stronger depolarization
  • includes IPSP
• Ven Diagram of EPSP:

  Only Temp: one after another; one one synapse

  Only Spat.: same time; different synapse; IPSP

  Both: 2+ EPSP; strong depolarization
• Summation is how EPSP and IPSP cancel each other out to reach threshold which would allow Ap to happen again, if IPSP are more than EPSP threshold will not be met and AP will not happen again.