neuron structure & function

• How is activity in the nervous system compared in the chapter?

  To internet "traffic"
• What are neurons?

  Nerve cells that send signals
• How many neurons are in the human nervous system?

  Around 100 billion
• Where do 80% of neurons reside?

  In the brain
• What are the three types of neurons?

  • Sensory neurons
  • Relay neurons
  • Motor neurons
• What do sensory neurons do?

  Carry messages from PNS to CNS
• What is the structure of sensory neurons?

  Long dendrites and short axons
• What do relay neurons connect?

  Sensory neurons to motor neurons
• What is the structure of relay neurons?

  Short dendrites and short axons
• What do motor neurons do?

  Carry messages from CNS to effectors
• What is the structure of motor neurons?

  Short dendrites and long axons
• What is the length range of neurons?

  Less than a millimetre to a metre
• What are the main parts of a neuron?

  • Dendrite
  • Soma
  • Nucleus
  • Terminal button
  • Axon
  • Myelin sheath
  • Node of Ranvier
• What does the soma of a neuron contain?

  The nucleus with genetic material
• What do dendrites do?

  Carry signals to the cell body
• What is the function of the axon?

  Carry signals away from the cell body
• What is the myelin sheath?

  A fatty layer that protects the axon
• What are Nodes of Ranvier?

  Gaps in the myelin sheath
• What happens at the terminal buttons?

  Communicate with the next neuron
• What occurs when a neuron is at rest?

  The inside is negatively charged
• What happens when a neuron fires?

  The electrical charge changes briefly
• What creates the electrical signal in a neuron?

  Action potential
• How do neurons communicate with each other?

  Via synaptic transmission
• What is the synaptic cleft?

  The space between neurons
• What happens when an electrical signal reaches the terminal button?

  Neurotransmitters are released
• What do neurotransmitters do after release?

  Travel across the synaptic cleft
• What happens at the postsynaptic receptor sites?

  The chemical message turns back into an electrical impulse
• What happens to leftover neurotransmitters in the synaptic cleft?

  They are broken down by enzymes
• What effect do excitatory neurotransmitters have?

  Increase the neuron's positive charge
• What effect do inhibitory neurotransmitters have?

  Increase the neuron's negative charge
• What is summation in neuron communication?

  Combining excitatory and inhibitory signals
• What happens if there are enough excitatory signals?

  The neuron will fire
• What does summation cause in a neuron?

  Creation of an electrical impulse
• What is the study tip provided in the chapter?

  • Remember complex terms like "supercalifragilisticexpialidocious"
  • Make difficult words your friends