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Neurotransmitters and the Synapse What are ways in which you communicate with your friends? Neurotransmitters are the means of communication for neurons. However, they can illicit action or stop all communication. How are neurotransmitters and the neuron linked to psychology? What is their importance? Quick review of the Neuron parts Lecture Covering neurotransmitters Activity http://www.youtube.com/watch?v=HXx9qlJe tSU What neurotransmitters do Neurotransmitters are central to memory, learning, mood, behavior, sleep, pain perception and sexual urge. They operate at the junctions between neurons, allowing communication between cells. involved in voluntary movement, learning, memory, and sleep Too much acetylcholine is associated with depression, and too little in the hippocampus has been associated with dementia. inhibits excitation and anxiety Major inhibitory neurotransmitter in Brain Too little GABA is associated with anxiety and anxiety disorders. Some anti-anxiety medication increases GABA at the receptor sites. Common neurotransmitter in the brain Always excitatory and driven by the SodiumPotassium pump Receptors concentrated in the Cerebral Cortex especially the hippocampus Reabsorption of Glutamate is affected during mercury poisoning plays a role in mood, sleep, appetite, and impulsive and aggressive behavior Too little serotonin is associated with depression and some anxiety disorders, especially obsessive-compulsive disorder. Some antidepressant medications increase the availability of serotonin at the receptor sites. involved in energy, and glucose metabolism Too little epinephrine has been associated with depression. associated with eating, alertness § Too little norepinephrine has been associated with depression, while an excess has been associated with schizophrenia. • correlated with movement, attention, and learning – Too much dopamine has been associated with schizophrenia, and too little is associated with some forms of depression as well as the muscular rigidity and tremors found in Parkinson’s disease. involved in pain relief and feelings of pleasure and contentedness PERIPHERAL NERVOUS SYSTEM Only two neurotransmitters Acetylcholine (Ach) Norepinephrine CENTRAL NERVOUS SYSTEM Many Neurotransmitters Why? ▪ Brain functions are not as uniformed ▪ Many neurotransmitters to perform many different tasks http://www.youtube.com/watch?v=90cj4NX8 7Yk Many drugs and chemicals influence synaptic transmission Drugs can be agonistic or antagonistic But not all drugs increase dopamine levels in the brain in the same way. Some substances imitate natural neuromediators and take their place on their receptors. Morphine, for example, binds to the receptors for endorphin (a natural "morphine" produced by the brain), while nicotine binds to the receptors for acetylcholine. • Other substances increase the secretion of natural neuromediators. Cocaine, for example, mainly increases the amount of dopamine in the synapses, while ecstasy mainly increases the amount of serotonin. • Still other substances block a natural neuromediator. Alcohol, for example, blocks the NMDA receptors. • • • • • Increase synthesis of neurotransmitter Increase release of neurotransmitter Activate receptors, mimic neurotransmitter Inhibit reuptake of neurotransmitter Interfere with release of neurotransmitter Occupy and block neurotransmitter sites Cause neurotransmitter loss from vesicles. Agonists mimic the neurotransmitter by binding to the receptor sites just as the neurotransmitters do and having the same effect on the receiving neuron. Agonists are used when it is believed that there is not enough neurotransmitter • Antagonists BLOCK the neurotransmitter by binding to the receptor sites without affecting the receiving neuron in the same way. Because they “fill” the receptor sites, the neurotransmitters can’t bind to the neuron. Antagonists are used when it is believed that there is TOO much of the neurotransmitter in the body. • • • When there is TOO LITTLE neurotransmitter in the body, drugs may also help by blocking reuptake and thus increasing the amount of neurotransmitter that remains in the synapse Prozac is an example of this sort of drug. Prozac falls in a class of drugs called SSRI’s (Selective Serotonin Reuptake Inhibitor) and by inhibiting reuptake of serotonin, they increase the levels of this neurotransmitter in the brain.