lesson11 - 11 Transmitters, Drugs, and Disorders Key Terms...

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11 Transmitters, Drugs, and Disorders Key Terms and Concepts o Agonist o Obsessive- compulsive disorder o Antagonist o Acetylcholine o Curare o Serotonin o Reuptake o Catecholamines o Inactivation o GABA o Schizophrenia o Peptides o Dopamine hypothesis o Neuromodulators o Chlorpromazine o Metabotropic o Clozapine o Ionotropic o Parkinson’s disease o Lateralization o Depression o Microtubule The Neurotransmitters After the first discovery of a neurotransmitter, acetylcholine, in the 1920s, many other chemicals have been found that mediate communication between neurons. One estimate puts the total at 100 or more, some of which also have other functions elsewhere in the body. The discovery of new neurotransmitters has been extremely rapid in the past 20 years due to rapidly advancing biochemical and genetic techniques, and to well-funded research programs because of the involvement of these chemicals in health and disease. This area of neurobiology is advancing very rapidly, so instead of attempting an up-to-the-minute review of all these Lesson 11 135
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substances, which could easily fill a book in itself, we will review the better-known neurotransmitters individually and some of the others as groups. The four primary groups of neurotransmitters and some examples are provided in the following table. Acetylcholine Monoamines Serotonin Dopamine Norepinephrine catecholamines Epinephrine Amino acids Glutamate Gamma-amino butyric acid Peptides Vasopressin Oxytocin Substance P The neurotransmitters can be classified according to their chemical structure. One of the most widespread neurotransmitters, acetylcholine (ACh) is used to initiate muscle contraction. ACh is also found throughout the central nervous system where it is excitatory at some synapses and inhibitory at others. The monoamine group contains serotonin or 5-hydroxytryptamine (5HT). Cell bodies of neurons that produce 5HT are restricted to a small area of the brain but their axons extend widely. A subset of the monoamines is the catecholamines such as dopamine, norepinephrine, and epinephrine (adrenalin). Like 5HT, these neurotransmitters are produced by rather small clusters of neurons, but their importance is undeniable due to the widespread extension of catecholamine-releasing axons throughout the brain. Several amino acids, the building blocks of proteins (Lesson 2), have been identified as neurotransmitters. The most widespread of them is gamma-aminobutyric acid (GABA). Although GABA is an amino acid, it is not incorporated into proteins, but instead is found at an estimated one-third of all synapses where it is usually inhibitory. Finally, a large number of peptides influence neuronal communication. Peptides are short chains of amino acids that occur in the brain and in many other organs such as the gut and liver. The neuropeptides occur in small quantities in many parts of the brain, and are the most recently discovered and therefore least understood of the neurotransmitters. In fact, there are so
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This note was uploaded on 05/27/2010 for the course BIOS 373 B02 taught by Professor Dr.danielleger during the Spring '10 term at UNL.

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lesson11 - 11 Transmitters, Drugs, and Disorders Key Terms...

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