neurons + synaptic transmission

• what is a neuron

  cell in CNS allow messages to be transferred, allow us to function and respond to stimuli
• function of cell body

  • contains cell nucleus which holds genetic material for the neuron
  • contains mitochondria giving the cell energy
• function of myelin sheath

  • fatty deposits provide insulating layer & speeds up transmission
• function of dendrites


  • receive messages from other neurons to trigger action potential ( electrical impulse )
• functions of nodes of ranvier

  • break along myelin sheath on cell body, helps speed up transmission
• functions of axon


  • extensions of cell body which electrical impulse passes down towards axon terminals
• function of axon terminals

  • end of neuron that makes a synaptic connection with another neuron in body
  • they contain neurotransmitters
• describe neurotransmitters


  - chemical messengers that act between the neurons in the brain

  - neurotransmitters are released into the synaptic gap and taken up by the receptors of dendrites of another neuron, to send or inhibit a message

  -these N.T then remain in synaptic gap where they are either reabsorbed by pre-synaptic neuron or destroyed by enzymes
• explain the 2 things that can happen once N.T binded to receptor of dendrites

  1 - excitatory transmission = speeds up action potential in the post synaptic cell ( e.g dopamine )

  2 - inhibitory transmission = slows down the action potential ( electrical impulse ) in the post-synaptic cell ( e.g serotonin GABA )
• describe dopamine


  - excitatory transmitter

  - related to emotion, cognitive functioning, posture and control of movements and addictions ( people get addicted to feeling of euphoria )
• describe serotonin


  - inhibitory transmitter

  - deals with mood control, feeling pain, sleep, hunger and regulation of body temperature
• GABA


  - inhibitory transmitter

  - it reduces activity of any neuron it binds to
• the process of synaptic transmission

  1 - electrical impulse ( action potential ) is triggered due to change in charge in the neuron

  2 - when the electrical impulse signal reaches the terminal button, it changes into a chemical message

  3 - chemical message is a neurotransmitter which is released from vesicles

  4 - N.T diffuses across the synapse to the next neuron

  5 - N.T binds with receptors on the next neuron to pass the message on

  6 - N.T is then either reabsorbed or is destroyed by enzymes in synapse returning the neuron to resting state
• supporting evidence of neuro transmission

  • Dee Higley studied rhesus monkeys in wild and found those killed or injured in reckless fights with older, larger monkeys were more likely to have low serotonin levels (serotonin inhibits aggression). This shows that neurotransmitters like serotonin affect behaviour such as aggression.​
  • Brisch - Irregularities in dopamine system found in amygdala, pre-frontal cortex and the hippocampus overactive in sz patients, supports role of dopamine in disorders such as schizophrenia. ​
• critical evidence of neurotransmission

  • Depatie found giving people drugs increase their dopamine does not create symptoms of sz as would be expected if excess dopamine caused it, suggests neurochemicals such as dopamine may not be the only explanation of the causes of schizophrenia. ​