Neuron structure and function

• Neurones

  • Cells that send messages through electrical and chemical signals throughout the nervous system
  • Three types: Sensory, relay and motor
• Nucleus

  • Contains genetic material
• Soma

  • Carries the nucleus
• Dendrites

  • Carry electrical signals to nearby neurones
• Axon

  • Carries the message through the neurone
• Myelin sheath

  • Protects axon and speeds up electrical signal
• Node of Ranvier

  • Speeds up electrical signal
• Terminal buttons

  • Communicates to a nearby neurone
• Synpatic transmission

  • When a neuron is resting, the inside is negatively charged
  • When a neuron fires, the electrical charge changes which causes an action potential
  • This creates an electrical signal which travels down the axon, ready to be passed on to another neuron.
• Sensory neurons

  • Carries messages from receptors to CNS
  • Long dendrites
  • Short axons
• Relay neurons

  • Carries messages from sensory neurons to motor neurons
  • Short dendrites
  • Short axons
• Motor neurons

  • Carries messages from CNS to effectors (Muscles)
  • Short dendrites
  • Long axons
• Synaptic transmission definition

  • The way that neurons communicate with each other.
  • Involves a message being passed chemically
• Synaptic transmission (1)

  • Electrical signal reaches the end of the presynaptic neuron and it arrives at the terminal buttons to be passed on to the postsynaptic neuron
• Synaptic transmission (2)

  • Electrical signals cause the vesicles to release neurotransmitters to the synaptic cleft
• Synaptic transmission (3)

  • Neurotransmitter crosses the synaptic cleft and makes its way to the postsynaptic neuron
  • Can only enter if it fits into receptor site on the postsynaptic neuron
  • E.g, dopamine can only fit into the dopamine receptor sites
• Synaptic transmission (4)

  • Neurotransmitter enters the receptor site and causes an electrical message in the postsynaptic neuron
  • Neurotransmitters left in the synaptic cleft might be reabsorbed by the presynaptic neuron by reuptake channels