IV. Neurotransmitters
So far, researchers have discovered about 15–20 different neurotransmitters, and new ones are still being identified. The nervous system communicates accurately because there are so many neurotransmitters and because neurotransmitters work only at matching receptor sites. Different neurotransmitters do different things. |
Neurotransmitter Acetylcholine _______________ Dopamine _______________ Serotonin _______________ Endorphins _______________ Norepinepherin _______________ GABA _______________ Glutamate _______________ |
Major Functions Muscle movement, attention, arousal, memory, emotion ______________ Voluntary movement, learning, memory, emotion ______________ Sleep, wakefulness, appetite, mood, aggression, impulsivity, sensory perception, temperature regulation, pain suppression ______________ Pain relief, pleasure ______________ Learning, memory, dreaming, awakening, emotion,stress-related increase in heart rate, stress-related slowing of digestive processes ______________ Main inhibitory neurotransmitter in the brain ______________ Main excitatory neurotransmitter in the brain ______________ |
Excess is Associated with
______________ Schizophrenia ______________ ______________ ______________ ______________ ______________ Multiple Sclerosis ______________ |
Deficiency is Associated with
Alzheimer's Disease ______________ Parkinsons ______________ Depression ______________ ______________ Depression ______________ ______________ ______________ |
Vocabulary to Learn Today
Agonist Antagonist |
Agonists and Antagonists
Agonists are chemicals that mimic the action of a particular neurotransmitter. They bind to receptors and generate postsynaptic potentials.
Example: Nicotine and Receptors
Nicotine is an acetylcholine agonist, which means that it mimics acetylcholine closely enough to compete for acetylcholine receptors. When both nicotine and acetylcholine attach to a receptor site, the nerve fibers become highly stimulated, producing a feeling of alertness and elation.
Antagonists are chemicals that block the action of a particular neurotransmitter. They bind to receptors but can’t produce postsynaptic potentials. Because they occupy the receptor site, they prevent neurotransmitters from acting.
Example: Paralysis and Poison Arrows
Curare is a drug that causes paralysis. As an acetylcholine antagonist, it binds to acetylcholine receptors at nerve-muscle junctions, preventing communication between nerves and muscles. Doctors sometimes use curare to immobilize patients during extremely delicate surgery. South American tribes have long used curare as an arrow poison.
Agonists are chemicals that mimic the action of a particular neurotransmitter. They bind to receptors and generate postsynaptic potentials.
Example: Nicotine and Receptors
Nicotine is an acetylcholine agonist, which means that it mimics acetylcholine closely enough to compete for acetylcholine receptors. When both nicotine and acetylcholine attach to a receptor site, the nerve fibers become highly stimulated, producing a feeling of alertness and elation.
Antagonists are chemicals that block the action of a particular neurotransmitter. They bind to receptors but can’t produce postsynaptic potentials. Because they occupy the receptor site, they prevent neurotransmitters from acting.
Example: Paralysis and Poison Arrows
Curare is a drug that causes paralysis. As an acetylcholine antagonist, it binds to acetylcholine receptors at nerve-muscle junctions, preventing communication between nerves and muscles. Doctors sometimes use curare to immobilize patients during extremely delicate surgery. South American tribes have long used curare as an arrow poison.