neurons

• 🧠 define neuron

  nerve cells that transmit messages around body in form of electrical and chemical signals
• 3 types of neuron

  1. sensory
  2. relay
  3. motor
• function of sensory neurons

  carry messages from sensory receptors to the CNS
• 🔄 direction of sensory neurons

  PNS to CNS
• 🧱 structure of sensory neurons

  • short axon
  • long dendrites
• 🔑 function of relay neurons

  connect sensory neurons to motor neurons
• 🔄 direction of relay neurons

  within the CNS
• 🧱 structure of relay neurons

  • short dendrites
  • short axons
• 🔑 function of motor neurons

  carry messages from CNS to effectors
• 🔄 direction of motor neuron

  from CNS to the body
• 🧱 structure of motor neuron

  • long axon
  • short dendrites
• what is synaptic transmission?

  nerve impulse reaches end of neuron so transmitted chemically across a synapse
• 🪜 step-by-step of synaptic transmission

  1. electrical impulse travels down the axon to presynaptic terminal
  2. release of neurotransmitters from vesicles
  3. released into synaptic cleft
  4. bind to receptors on postsynaptic neuron
  5. triggers new electrical impulse
  6. reuptake
• define neurotransmitters

  chemical messengers that affect if next neuron will fire an impulse
• 2 effects of neurotransmitters

  1. excitation
  2. inhibition
• what determines if a neuron fires?

  net effect of all excitatory and inhibitory neurotransmitters
• 🎉 excitation

  • makes postsynaptic neuron more likely to fire
  • depolarisation

  e.g. glutamate or adrenaline
• 🧱 structure of neuron

  • Dendrites - receive messages
  • Cell Body - contains nucleus to keep neuron functioning
  • Axon - transmits electrical impulse
  • Myelin Sheath - fatty layer insulating axon to speed up transmission
  • Nodes of Ranvier - gaps to allow impulses to jump
  • Axon Terminals - pass signal to next neuron or effector

  
• 🚫 inhibition

  • makes postsynaptic neuron less likely to fire
  • hyperpolarisation

  e.g. GABA or serotonin
• ✅ neurons

  medical treatments

  • SSRIs treat depression by increasing serotonin levels
  • targeted medical interventions by altering neurotransmitter activity
  • practical benefits
• ✅ neurons

  scientific rigor and objectivity

  • use of EEG, fMRI and brain imaging provide objective data
  • findings are replicable
  • increases credibility
• ❌ neurons

  oversimplification

  • ignores the social, environmental and psychological factors
  • too reductionist