Synaptic Transmission

• Why is understanding synaptic transmission important in biological psychology?

  It helps understand information transfer and drug effects
• What is synaptic transmission?

  • Process of communication between neurons
  • Involves electrical impulses and neurotransmitters
  • Occurs at the synapse
• What are the chemical messages called that transmit information across the synapse?

  Neurotransmitters
• What happens when an action potential reaches the axon terminal?

  It causes vesicles to merge and release neurotransmitters
• What is the gap between two neurons called?

  Synaptic cleft
• How wide is the synaptic cleft?

  About 20 to 40 nanometers
• What do the receptors on the postsynaptic neuron detect?

  Neurotransmitters
• What is the role of transport proteins in the presynaptic neuron?

  They take neurotransmitters back into the cell
• What are the steps of synaptic transmission?

  1. Action potential arrives at axon terminal
  2. Vesicles merge and release neurotransmitters
  3. Neurotransmitters diffuse across synaptic cleft
  4. Summation occurs in postsynaptic cell
  5. New action potential forms if threshold is reached
• What is summation in synaptic transmission?

  It is the net effect of excitatory and inhibitory signals
• What happens during depolarization in the postsynaptic neuron?

  Positively charged sodium ions enter the cell
• What effect do excitatory neurotransmitters have on the postsynaptic neuron?

  They make the electrical charge more positive
• What do inhibitory neurotransmitters do to the postsynaptic neuron?

  They hyperpolarize the neuron, making it more negative
• What is the typical firing rate of a neuron?

  Between 5 and 50 times a second
• What do SSRIs do in the brain?

  They block serotonin reabsorption, increasing levels
• How does cocaine affect neurotransmitter transmission?

  It blocks dopamine reabsorption, increasing its signal
• What is the significance of synapses in brain function?

  • Fundamental for consciousness and memory
  • Enable complex interactions between neurons
  • Essential for all brain functions
• How many neurons are estimated to be in the human brain?

  Around 100 billion neurons
• How many synaptic connections can a single neuron have?

  Up to 15,000 synaptic connections
• How many synapses does an average 20-year-old male have?

  Around 170 trillion synapses
• How long would it take to count all synapses at a rate of 100 per second?


  Just under 5,500 years
• What analogy is used to describe the number of synapses in the brain?

  • Equivalent to 680 Milky Way galaxies
  • Comparison to stars in the Milky Way
• What is the main takeaway about the brain's complexity?

  It is a powerful machine due to synaptic interactions
• What is the communication direction in synaptic transmission?

  It is unidirectional or one-sided
• What happens to neurotransmitters after they are detected?

  They detach, are broken down, or recycled
• What resets the presynaptic cell for the next firing?

  Reuptake of neurotransmitters