Impulses at synapses (8.4)

Question 1

Describe the sequence of events that takes place at an excitatory synapse when a nerve impulse arrives at a pre-synaptic neuron

Answer 1

An action potential arrives at the end of the pre-synaptic neuron. This causes calcium gated channels to open and calcium flood the pre-synaptic neuron. The increase in calcium ions results in vesicles containing chemicals to leave the pre-synaptic neuron via exocytosis

Question 2

Describe the sequence of events that takes place at an excitatory synapse when a nerve impulse arrives at a pre-synaptic neuron

Answer 2

An action potential arrives at the end of the pre-synaptic neuron. This causes calcium gated channels to open and calcium flood the pre-synaptic neuron. The increase in calcium ions results in vesicles containing inhibitory chemicals to leave the pre-synaptic neuron via exocytosis. These enter the synapse and bind to receptors on the post synaptic preventing an impulse to continue

Question 3

State the role of acetylcholine and acetylcholinesterase

Answer 3

Acetylcholine binds to receptors on the post synaptic and is an excitatory so results in the continuation of a nerve impulse.
Acetylcholinesterase is an enzyme that terminates any remaining acetylcholine in the synapse to prevent it from continuously stimulating the post synaptic neuron