NeurotransmittersAP Psychology

Neurons

Neurons don’t actually touch Separated by a tiny fluid-filled gap

called a synapse Neural impulses must be ferried

across the synapse by chemical messengers called neurotransmitters.

NeurotransmittersBiochemical substances that are released into the synaptic cleft to stimulate or suppress other neurons.

Dozens of neurotransmitters have been identified.

Each type of (NT) has a three-dimensional shape.

The journey across the synapse takes only a thousandth of a second.

Neuron PotentialNeurons are electrically chargedResting potential – the state of the neuron when not firing

a neural impulse.Action potential – the release of the neural impulse

consisting of a reversal of the electrical charge within the axon. During this state inside of a neuron is positive and outside is

negative. Allows impulses (messages) to transfer.

Excitatory or InhibitoryChanges the neurotransmitter makes to the

neuron have either an excitatory effect or an inhibitory effect.

Excitatory Activates the next cell Makes an action potential more likely to occur in

receiving neuron Hooked to a positive ion channel

Inhibitory Less likely that the cell will fire Hooked to a negative ion channel

NT

Some NT have only Excitatory effectsSome NT have only Inhibitory effectsSome NT have both

Preventing the ENT from stimulating a receiving cell

Reuptake: NT not taken up by the receiving cell are reabsorbed by their vesicles to be used again. Nature’s own version of recycling.

Enzymes: organic substances in the synapse break down NT, which are then eliminated from the body in the urine.

How do drugs impact NTs NT originate in the body Drugs originate outside of the body. Antagonists: drugs or chemicals that block the actions of

NTs by occupying their receptor sites. Antagonists prevent transmission of the messages carried by

the NT Compete with NTs at the same receptor sites

How do drugs impact NTs

Agonists: drugs that either increase the availability or effectiveness of NT or mimic their actions.

5 NT that students need to KNOW1. Acetylcholine (ACh): NT that enables motor function in the body. Ex. Wiggle my fingers.

makes muscles contract (motor cortex)Role in learning and memory. If ACh transmission is blocked, the muscles cannot contract.

AChUnderproduction of ACh is an important factor in Alzheimer’s disease

Reductions in ACh weaken or deactivate neural circuitry that stores memories.

AChAbsence: ParalysisOversupply: violent muscle contractionsCertain spider bites/Black widow

5 NT that Students need to KNOW2. Endorphins: natural chemicals released in the brain that have pain-killing and pleasure-inducing effects. Blocks pain.

Inhibitory NT

EndorphinsLocated in the Brain, pituitary gland, and spinal cord.

“runners high”Morphine and heroin are agonists since they mimic the effects of endorphins.

5 NT that students need to KNOW3. Serotonin: affects mood, hunger, temp regulation and sleep. Inhibitory or excitatory

Located in the brain stem, cerebellum, pineal gland, and the spinal cord.

Undersupply may lead to depression, sleeping and eating disorders.

Oversupply linked to OCD

SerotoninProzac acts as a agonistProzac elevates serotonin levelsBest selling antidepressant! 40 million patients

Some other antidepressant drugs raise serotonin levels

5 NT That students need to KNOW 4. Dopamine: influences body movement, learning, attention, reward experiences, and emotion.

Located in the brain and the peripheral nervous system.

excess dopamine receptor activity linked to schizophrenia.

Antipsychotic drugs like Theorize are antagonists that block receptor sites for dopamine.

DopamineParkinson’s Disease: a degenerative brain disease that leads to a progressive loss of motor function. Experience tremors, shakiness, rigidity, and difficulty in walking.

Lack normal levels of dopamine.Ex. Michael J. FoxMuhammad Ali

5 NT that students need to KNOW

5. Gamma-aminobutyric acid (GABA): a major inhibitory NT.

Regulates nervous activity by preventing neurons from overly exciting their neighbors.

Located in the retina, spinal cord, hypothalamus, and cerebellum.

Exists in as many as a third of all synapses.Drugs that boost GABA’s effects have a calming or relaxing effect.

Reduced levels of GABA may play a role in emotional disorders in which anxiety is a core feature.

GABAAlcohol and anti-anxiety drugs like Valium, act as agonists

GABARohypnol (roofies): suppress general neural activity by enhancing the action of GABA. Rohypnol is 10 times more potent than Valium.

Coma, amnesia, respiratory depression, and death.