Kaplan MCAT Behavioral Sciences Review, Chapter 1, Lesson 5. Influences on behavior

Kaplan MCAT Behavioral Sciences Review, Chapter 1, Lesson 5. Influences on behavior

Neurotransmitter

There are more than 100 of these chemicals that are used by neurons to send signals to other neurons

Agonist

A drug that mimics the action of some neurotransmitter

Antagonist

A drug that acts by blocking the action of neurotransmitters

Acetylcholine

In the peripheral nervous system, it is used to transmit nerve impulses to the muscles. It is used by the parasympathetic nervous system and a small part of the sympathetic nervous system (in ganglia and for innervating sweat glands). In the central nervous system, it has been linked to attention and arousal. A loss of the neurons that use this neurotransmitter connecting with the hippocampus is associated with Alzheimer’s disease (an illness resulting in progressive and incurable memory loss). It may be either excitatory or inhibitory in cardiac muscle cells. In skeletal muscle cells and in the central nervous system, it is largely an excitatory neurotransmitter.

Epinephrine (Adrenaline)

A neurotransmitter involved in controlling alertness and wakefulness, it promotes the fight-or-flight response. It is often secreted by the adrenal medulla to act systematically as a hormone.

Norepinephrine (Noradrenaline)

A neurotransmitter involved in controlling alertness and wakefulness, it promotes the fight-or-flight response. It acts at a local level as a neurotransmitter. Low levels of it are associated with depression, high levels are associated with anxiety and mania.

Dopamine

High concentrations of this neurotransmitter are found in the basal ganglia, where it helps to smooth movements and maintain postural stability. There is a hypothesis of this neurotransmitter related to schizophrenia, suggesting that the delusions, hallucinations, and agitation associated with schizophrenia arise from too much of this neurotransmitter or from an oversensitivity to this neurotransmitter in the brain. That hypothesis does not account for all of the findings of the disease. Parkinson’s disease is associated with a loss of neurons regarding this neurotransmitter in the basal ganglia.

Serotonin

A neurotransmitter that is thought to play roles in regulating mood, eating, sleeping, and dreaming. Like norepinephrine, it is thought to play a role in depression in mania, with an oversupply producing manic states and an undersupply producing depression.

Catecholamines

Includes epinephrine, norepinephrine, and dopamine

Monoamines / Biogenic amines

Includes catecholamines and serotonin

Gamma-aminobutyric acid (GABA)

A neurotransmitter which produces inhibitory postsynaptic potential (through hyperpolarizing the postsynaptic membrane) and is thought to play an important role in stabilizing neural activity in the brain.

Glycine

A proteinogenic amino acid, it is an inhibitory neurotransmitter in the central nervous system which increases chloride influx into the neuron, and it hyperpolarizes the postsynaptic membrane.

Glutamate

A proteinogenic amino acid, it is an excitatory neurotransmitter in the central nervous system.

Endorphins

Natural painkillers produced in the brain. They are related to enkephalins and have actions similar to morphine and other opioids in the body.

Neuromodulators / Neuropeptides

They include endorphins and involve a more complicated chain of events than regular neurotransmitters.