Neurotransmission Systems

This flashcard set covers the neurotransmission systems, including definition criteria, life cycles, classifications of neurotransmitters (Amines, Amino Acids, Neuropeptides, Lipids), and their specific functions and associated disorders.

Neurotransmitter

Chemical messengers synthesized inside the presynaptic neuron and released in response to $Ca^{2+}$ depolarization upon the arrival of an action potential.

Reuptake process

A method of removing neurotransmitters from the synaptic cleft where the presynaptic neuron reabsorbs molecules through special transporter proteins to be stored back in vesicles or broken down.

Inactivating process

A removal method where neurotransmitter molecules remaining in the synaptic cleft are just destroyed.

Acetylcholine (ACh)

The main neurotransmitter of efferent axons of the PNS with facilitating effects; it is involved in movement, learning, and memory.

Alzheimer

An associated pathology characterized by decreased $ACh$ level, treated with anti-acetylcholinesterase inhibitors.

Myasthenia Gravis

A condition characterized by skeletal muscle weakness that is treated with anti-acetylcholinesterase inhibitors.

Neuromodulators

Substances, such as those highlighted in yellow in the notes, whose function is to modify how neurons respond to other neurotransmitters.

Monoamines

A group of neurotransmitters derived from amino acids containing an amine ($-NH_2$) group; it includes catecholamines and indolamines.

Dopamine (DA)

A catecholamine that travels through four pathways: nigrostriatal, mesocortical, mesolimbic, and tuberoinfundibular.

Parkinson

A disorder related to the degradation of the nigrostriatal dopaminergic pathway.

Schizophrenia

A disorder related to the degradation of the mesolimbic dopaminergic pathway.

Axonal varicosities

Small bulges along the axon that release neurotransmitters like Noradrenaline and Serotonin from many swellings rather than a single terminal ending.

Noradrenaline (NA)

A neurotransmitter released from axonal varicosities that increases vigilance and regulates sleep, hunger, and motor activity.

Adrenaline (A)

A neurotransmitter synthesized in the sequence Tyrosine $\rightarrow$ L-DOPA $\rightarrow$ Dopamine $\rightarrow$ Noradrenaline $\rightarrow$ Adrenaline; it prepares the body to react to stress.

Serotonin (5-HT)

An indolamine, with 90\text{ %} located in the digestive system, that regulates mood, impulsive behavior, and pain.

Histamine (H)

A monoamine synthesized from Histidine that functions in attention and memory within the CNS and controls allergies and cell damage in the PNS.

Glutamate

The main excitatory neurotransmitter of the CNS; it is abundant in the cerebral cortex and converted into glutamine inside glia cells for safety.

Excitotoxicity

A pathology associated with overexcitation caused by Glutamate.

Chinese food syndrome

A condition related to Glutamate characterized by vertigo, nausea, tachycardia, and temporary paralysis.

GABA

The main inhibitory neurotransmitter of the CNS; its lack of inhibition is associated with epilepsy and anxiety.

Glycine

An amino acid neurotransmitter with inhibitory functions regulating motor behavior and tissue regeneration; associated with tetanus and the toxic antagonist strychnine.

Neuropeptides

A class of neurotransmitters including endogenous opioid peptides like Enkephalins, Endorphins, and Dynorphins that have hormonal and neuromodulatory functions.

Endocannabinoids

Lipid neurotransmitters like 2-AG that are produced and diffused immediately when the postsynaptic neuron is active and act on presynaptic receptors in a retrograde synapse.

CB1 and CB2

The two kinds of receptors for endocannabinoids, found in the brain and the immune system respectively.