Neurotransmitters are natural chemicals that transmit signals from a neuron (nerve foot process) to a target nerve (head process=dendrite) across a synapse (gap between nerves) Neurotransmitters are packaged into synaptic vesicles
clustered beneath the membrane in the axon terminal (nerve foot process), on the pre-synaptic
side(nerve before the synapse) of a synapse. They are released into and diffuse across the synaptic cleft (space between the nerves) , where they bind to specific receptors in the membrane on the post-synaptic side (nerve on the other side of the synapse) of the synapse. Release of neurotransmitters usually follows arrival of an action potential (nerve impulse) Neurotransmitters are synthesized from plentiful and simple
precursors, which are readily available from the diet and which require only a small number of biosynthetic steps to convert.
effects of a neurotransmitter system depend on the connections of the
neurons that use the transmitter, and the chemical properties of the
receptors that the transmitter binds to.
is used at the great majority (~90%) of fast excitatory synapses in the brain
and spinal cord. It is also used at most synapses that are “modifiable”,
i.e. capable of increasing or decreasing in strength. Modifiable synapses are thought to be the main memory-storage elements in the brain. Excessive glutamate release can lead to excitotoxicity causing cell death.
is used at the great majority of fast inhibitory synapses in virtually
every part of the brain. Many sedative/tranquilizing drugs act by
enhancing the effects of GABA such as baclofen. Correspondingly glycine is the inhibitory transmitter in the spinal cord.
neurons. It functions to regulate appetite, sleep, memory and learning,
temperature, mood, behaviour, muscle contraction, and function of the cardiovascular system and endocrine (Hormone) system.
distinct systems, where activation of the system affects large parts of the brain, called volume transmission. Major neurotransmitter systems include the noradrenaline (norepinephrine) system, the dopamine system, the serotonin system and the cholinergic system.
I don’t understand the complexity of all this and so don’t worry if you don’t understand it too!The take-home message is that this is all very complex and unravelling it, means that there is a difficult task ahead.