This week we backtracked from sensory systems to neurotransmitter systems. We got a little more in-depth explanation on functions of different neurotransmitters and -receptors. One type of neurotransmitter is usually used in each synaptic transmission, but it’s not limited to only one. Recently we have learned that ATP can function as a neurotransmitter and it can be stored in vesicles together with some other neurotransmitter. It is also very important to know that same neurotransmitter can effect different receptors and have completely different effect.
We went through life cycle of ACh and learned also what happens after the neurotransmitter has been released to the synaptic cleft. Some of the neurotransmitters are transported back to the presynaptic neuron to clear the synaptic cleft, but this process can be interfered with by using some kind of drug for example and it can greatly affect the excitability of the neuron.
We also had an example of second messenger cascades and the various effects it can have compared to transmitter-gated ion channels. These systems are the brains way to modulate action in the future so that we can ultimately adapt our behavior.
One very interesting thing we learned was how neurons die when they lack energy to keep up the membrane potential. This results in death by excitotoxicity. I would imagine some drugs can also cause this if for example inhibition is prevented (some GABA receptor antagonist maybe).