bio-psych

• Neurons


  The basic building blocks of the nervous system, nerve cells that process and transmit messages
• There are over 100 billion neurons in the human nervous system, over 80% of which are in the brain
• Main types of neurons

  • Relay neuron
  • Sensory neuron
  • Motor neuron
• Sensory neuron


  Carries messages from the peripheral nervous system to the central nervous system
• Relay neuron


  Connects sensory receptors/neurons to motor neurons or other relay neurons
• Motor neuron


  Connects the central nervous system to effectors like muscles and glands
• Stimulus to response


  1. Stimulus

  2. Sensory neuron

  3. Relay neuron

  4. Motor neuron

  5. Effector response
• Neuron structure


  • Cell body with nucleus
  • Dendrites carry impulses towards cell body
  • Axon carries impulses away from cell body
  • Axon covered in myelin sheath with nodes of Ranvier
  • Terminal buttons communicate with next neuron across synapse
• Resting state of neuron

  Negatively charged inside
• Action potential


  When neuron is activated, inside becomes positively charged for a split second, causing an electrical impulse
• Electrical to chemical transmission


  1. Electrical impulse reaches presynaptic terminal

  2. Neurotransmitters released from synaptic vesicles into synapse

  3. Neurotransmitters bind to receptors on postsynaptic neuron

  4. Chemical message converted back to electrical impulse
• Neurotransmitters


  Chemical messengers that diffuse across the synapse
• Neurotransmitters can have excitatory or inhibitory effects on neighbouring neurons