synapses

• what are the two types of synapse


  electrical and chemical
• what is meant by an electrical synapse


  this is a tiny gap that is small enough for an electrical impulse to be transmitted directly across
• how big is a electrical synapse


  3nm
• what is meant by a chemical synapse


  this is when branches of axons lie close to dendrites and the impulses is transmitted across the synaptic cleft chemically as a neurotransmitter
• how does an electrical impulse cross a chemical synapse


  as a neurotransmitter
• what happens when the action potential arrives at the axon terminal


  it causes the voltage gated calcium ion channel to open
• what happens after the calcium ion channel opens because there is a action potential at the axon terminal


  the calcium ions diffuse into the presynaptic knob
• what happens after the calcium ions diffuse into the presynaptic knob


  it causes vesicles containing acetylcholine to fuse with the presynaptic membrane
• give three examples of a neurotransmitter


  acetylcholine , dopamine and serotonin
• after the calcium ions have cause the release of neurotransmitters ,where are they released too and by what process


  into the synaptic cleft by exocytosis
• what happens to the the neurotransmitters after they have reached the synaptic cleft


  they diffuse over the synaptic cleft and bind to specific receptors on the post synaptic membrane
• what happens after the neurotransmitter reaches the post synaptic membrane


  it causes the sodium ions channels to open
• what happens when the sodium ion channels open in the post synaptic membrane


  the sodium ions diffuse in and depolarise the post synaptic membrane
• what needs to happen when sodium ions diffuse into the post synaptic membrane in order to prompt a electrical impulse in the other axon


  it needs to reach the the threshold value
• what is acetylcholine broken down by


  acetylcholinesterase
• What is acetylcholine?


  a neurotransmitter
• what is acetylcholine broken down into


  ethanoic acid and choline
• what happens to the acetylcholine when it is broken down into ethanoic acid and choline in the post synaptic membrane


  it will diffuse back into the axon terminal through the presynaptic membrane
• what is required to re-synthesise and package the neurotransmitters into vesicles


  atp
• what happens to the neurotransmitter to restore the axon back to resting potential


  calcium ions are actively transported back out the synaptic knob