Lecture 18 Flashcards
What is the chemical synapse
The junction between nerve cells were an action potential is transferred from on neuron to another or to a muscle.
What can acetyl choline do to affect membrane potential?
Can open the gate/ ion channel, by binding to the protein causes the channel to open. Basically turning on the membrane potential.
What can a presynaptic neuron attach to?
A postsynaptic neuron or a muscle fibre.
What do synaptic vesicles carry?
The neurotransmitter
What is in the cleft?
Enzymes
What type of enzyme is in the cleft?
AChE so acetyl choline esterase
What is AChE important for?
Useful for terminating chemical synaptic transmissions.
Why are mitochondria important?
Because they give energy to the synapse.
What is the first step to chemical synaptic transmission?
Action potential triggers the opening of voltage-gated calcium channels.
What is the second step to chemical synaptic transmission?
Calcium ions diffuse into the axon terminal and trigger synaptic vesicles to release ACh by exocytosis.
What is the third step to chemical synaptic transmission?
ACh diffuses across synaptic cleft, binds to ACh-gated sodium ion channels and produces a graded depolarisation, also called EPSP or Excitatory post synaptic potential.
What is the fourth step to chemical synaptic transmission?
Depolarisation ends as ACh is broken down into acetate and choline by AChE.
What is the fifth step to chemical synaptic transmission?
The axon terminal reabsorbs choline from the synaptic cleft and uses it to synthesise new molecules of ACh
What does EPSP stand for?
Excitatory post synaptic potential.
What does IPSP stand for?
Inhibitory post synaptic potential.
How fast are EPSP and IPSP
They are in the order of milliseconds, not as fast as action potentials, usually 5-10 milliseconds for these to appear.
Is there an axon hillock/ decision point in a neural muscular junction?
No otherwise you wouldn’t be able to move your muscles.
What does temporal mean?
In time
Can you add up action potentials?
Yes it helps to get over the axon hillock by adding more EPSP to get over the threshold and cause an action potential to occur!!
What happens when there is enough action potential?
Its called action potential propagation, and it has been allowed to travel down the axon hillock.
Temporal summation is…?
Summating those EPSP in time!!
What does spatial summation mean?
In space or adding up graded potentials in space.
What happens with there is two simultaneous action potentials occurring?
It leads to a large depolarisation as there is twice as much that can get a large action potential to overcome the axon hillock.
