A03

• What are groups of neurons called?

  Neural networks
• What is the tiny gap between neurons called?

  Synapse
• How are signals transmitted within neurons?

  Electrically
• How are signals transmitted between neurons?

  Chemically across the synapse
• What triggers the release of neurotransmitters?

  Electrical impulse reaching the presynaptic terminal
• What are neurotransmitters stored in?

  Synaptic vesicles
• What happens to neurotransmitters after they cross the synapse?

  They are taken up by postsynaptic receptor sites
• What do dendrites do in relation to signals?

  They take signals away from the synapse
• What is the direction of neurotransmitter travel?

  One-way from presynaptic to postsynaptic neuron
• How many types of neurotransmitters have been identified?

  Several dozen
• What is the relationship between neurotransmitters and receptor sites?

  Each neurotransmitter fits a specific receptor site
• What is the function of acetylcholine (ACh)?

  Causes muscles to contract
• What effect does serotonin have on the receiving neuron?

  It causes inhibition, making it negatively charged
• What effect does adrenaline have on the postsynaptic neuron?

  It causes excitation, increasing positive charge
• What determines whether a postsynaptic neuron fires?

  The process of summation of signals
• What happens if the net effect on the postsynaptic neuron is inhibitory?

  The neuron is less likely to fire
• What occurs when the net effect is excitatory?

  The postsynaptic neuron is more likely to fire
• What triggers the action potential in the postsynaptic neuron?

  When excitatory signals reach the threshold
• What happens to the inside of the postsynaptic neuron when it becomes positively charged?

  An electrical impulse is created