synapse

• What is the gap between neurons called?


  Synapse
• What is the chemical that carries nerve impulses across synapses?

  Neurotransmitter
• Where are neurotransmitters stored before being released into the synapse?

  Synaptic vesicles
• What triggers the release of neurotransmitters into the synaptic cleft?

  Calcium ions diffusing into the neuron
• What happens when neurotransmitters bind to receptor sites on the postsynaptic cell?

  Sodium channels open, allowing sodium ions to enter
• What is the resting membrane potential of a neuron?

  -70 mV
• What happens during depolarization of a neuron?

  Voltage-gated Na+ channels open, and the membrane potential rises to +40 mV
• What occurs during repolarization of a neuron?

  Na+ channels close, and K+ channels open, causing K+ to diffuse out
• What is hyperpolarization in a neuron?

  The membrane potential overshoots the resting potential, becoming more negative than -70 mV
• What restores the resting membrane potential after hyperpolarization?

  The sodium-potassium pump
• What are the stages of an action potential in a neuron?


  1. Resting potential: -70 mV maintained by sodium-potassium pump
  2. Depolarization: Na+ channels open, membrane potential rises to +40 mV
  3. Repolarization: Na+ channels close, K+ channels open, K+ diffuses out
  4. Hyperpolarization: Membrane potential overshoots resting potential
  5. Resting potential restored: Sodium-potassium pump resets membrane to -70 mV
• What are the steps of chemical transmission across a synapse?


  1. Action potential arrives at synaptic bulb
  2. Calcium channels open, Ca2+ diffuses into neuron
  3. Synaptic vesicles move toward presynaptic membrane
  4. Vesicles fuse with membrane, release neurotransmitters
  5. Neurotransmitters diffuse across synaptic cleft
  6. Neurotransmitters bind to postsynaptic receptor sites
  7. Sodium channels open, Na+ enters, action potential generated
• What is the name of the gap between the presynaptic and postsynaptic neurons?

  Synaptic cleft
• What role do voltage-gated calcium channels play in synaptic transmission?

  They allow Ca2+ to enter the neuron, triggering neurotransmitter release
• What is the threshold potential required to generate an action potential?

  Approximately -55 mV
• What is the function of the sodium-potassium pump in neurons?

  It maintains the resting membrane potential by moving Na+ out and K+ in
• What is the name of the cell that receives neurotransmitters at a synapse?

  Postsynaptic cell