neurons and synaptic transmission

• what are the three types of neurones?

  relay neuron

  motor neuron

  sensory neurone
• nucleus…

  control centre of the cell

  contains chromosomal DNA
• dendrites…

  receives the nerve impulse from the neurons
• axon…

  where the electrical signals pass along
• myelin sheath…

  insulates/protects the axon from external influences
• nodes of ranvier…

  speed up the transmission of the nerv impulse
• terminal buttons…

  sends signals to the adjacent cell
• motor neuron…

  carries messages from the CNS to effectors; such as muscles and glands

  has short dendrites and long axons
• sensory neuron…

  carries messages from the peripheral nervous system to the brain and spinal cord

  long dendrites and short axons
• relay neuron…

  transfers messages from sensory neurons to other relay or motor neurons

  short dendrites and short/long axons
• synaptic transmission…

  the process by which neighbouring neurons communicate by sending chemical signals across the gap (synapse) that separates them
• what happens when an electrical signal reaches the end of a neuron?

  neurotransmitters are released
• neurotransmitters…

  brain chemicals that are released from synaptic vesicles that relay signals across the synapse from one neuron to another
• action potential…

  occurs when a neuron sends information down an atom, away from the cell body

  an explosion of electrical activity
• what two things can synaptic connections be?

  excitatory or inhibitory
• excitatory…

  they make it more likely that the next neuron will fire
• inhibitory…

  make it less likely that the next neuron will fire
• normal brain function…

  depends upon a regulated balance between these two influences