Neurons and synaptic transmission

• What is the central nervous system composed of?

  All the neurons in the body
• What is a neuron?

  A nerve cell
• How do neurons carry messages?

  Electrically and chemically
• What role do neurons play in the body?

  They are the building blocks of communication
• What are the main parts of a neuron?

  • Dendrites
  • Cell body
  • Cell nucleus
  • Axon
  • Myelin sheath
  • Terminal buttons (or boutons)
  • Vesicles
• What is the function of dendrites?

  Receive signals from other neurons
• What does the cell body of a neuron contain?

  The nucleus and organelles
• What is the role of the axon?

  Transmit electrical impulses away from the cell body
• What is the myelin sheath?

  A protective covering that speeds up impulses
• What are terminal buttons?

  They release neurotransmitters into the synapse
• What are vesicles in a neuron?

  Small sacs that contain neurotransmitters
• What happens during action potential?

  The inside of the neuron becomes positively charged
• What triggers an action potential?

  Activation by a signal
• What is the threshold in action potential?

  The level that must be reached to trigger it
• What does "all-or-nothing" mean in action potentials?

  It either occurs fully or not at all
• How many action potentials can myelinated neurons conduct?

  Up to 500 action potentials per second
• What is synaptic transmission?

  • Communication between neurons
  • Involves neurotransmitters
  • Occurs across the synaptic cleft
• How do signals travel within a neuron?

  Transmitted electrically
• How do signals travel between neurons?

  Transmitted chemically
• What initiates synaptic transmission?

  Action potential reaching the terminal button
• What happens to neurotransmitters after they are released?

  They diffuse across the synapse
• What do neurotransmitters bind to after crossing the synapse?

  Postsynaptic receptors
• What is the role of postsynaptic receptors?

  Receive signals from neurotransmitters
• What happens to neurotransmitters that remain in the synapse?

  They are reabsorbed by the presynaptic neuron
• What are neurotransmitters?

  Chemical messengers between neurons
• How many neurotransmitters have been identified in the human brain?

  Several dozen
• What is the key and lock analogy in neurotransmitters?

  Each neurotransmitter fits a specific receptor
• What are the functions of key neurotransmitters?

  • Noradrenaline: Fight or flight response
  • Dopamine: Learning, attention, mood control
  • Serotonin: Mood control, hunger, pain
  • Acetylcholine: Muscle contraction, cognitive functions
  • GABA: Inhibitory function, relaxation
• What is the role of GABA?

  It inhibits messages in the brain
• What happens at low levels of GABA?

  Associated with anxiety
• What is the effect of excitatory neurotransmitters?

  They increase the likelihood of action potentials
• What is the effect of inhibitory neurotransmitters?

  They decrease the likelihood of action potentials
• What is summation in the context of neurons?

  Adding together signals received by a neuron
• What influences the postsynaptic neuron's response?

  The combined effect of excitatory and inhibitory signals