Neurotransmitters in the Nervous System -----TYPES OF NEUROTRANSMITTERS Flashcards
Causes skeletal muscle contraction (excitatory)
Acetylcholine (ACh)
Controls sympathetic effects on organs— Effects are either excitatory or inhibitory based on
whether the organ contains more alpha or beta receptors.
Noradrenalin/Norepinephrine (NA/NE)
Inhibits/suppresses skeletal muscle contractions
Dopamine
Controls Sleep/Wake Cycle
Serotonin
Excitatory NT used solely within the CNS
Glutamate
Inhibitory NT used solely within the CNS
GABA (gamma-aminobutyric acid)
Action potentials caused by this NT are interpreted by the brain as pain
Substance P
Natural painkillers that block pain sensations
Endorphins and Enkephalins
Excitatory in ganglia
Acetylcholine (ACh)
Emotions—Low levels can cause clinical depression
Noradrenalin/Norepinephrine (NA/NE)
Emotions—Involved in pleasure, reward, motivation
When released in response to an activity, dopamine reinforces that behavior.
Dopamine
Emotions—Low levels can cause clinical depression, anxiety, obsessions & compulsions
Serotonin
Especially important in learning and memory formation
Glutamate
Epilepsy Treatment—Anticonvulsants ↑ GABA release. This suppresses epileptic seizures
because GABA stops APs from being made.
GABA (gamma-aminobutyric acid)
Opioid Painkillers block its release & also activate natural painkiller pathways
What are some opioids?
Substance P
Opioid PKs: Morphine, Heroin, Oxycodone
Opioid Painkillers bind to their receptors
Endorphins and Enkephalins
Controls parasympathetic effects on organs–Effects are mostly excitatory (but can be inhibitory)
Acetylcholine (ACh)
Adrenergic Receptors, found in all organs, are divided into two types: alpha (α) & beta (β).
Noradrenalin/Norepinephrine (NA/NE)
Dopamine reuptake blocked by drug. Dopamine remains in synapses, flooding brain, stays active
for long periods, causing extreme “high.”
Addiction & Dopamine Dysregulation:
Several antidepressants are SSRIs: Selective Serotonin Reuptake Inhibitors
What are the names of the antidepressants?
Serotonin
Lexapro, Celexa, Zoloft
Excitotoxicity: Is toxic to neurons—literally “excites” them to death
Glutamate
Sedatives enhance GABA’s effects: Alcohol, Benzodiazepines (Valium & Xanax), Barbiturates
GABA (gamma-aminobutyric acid)
Cholinergic Receptors are divided into two types:
Nicotinic receptors are found in both skeletal muscle and in ganglia.
Muscarinic receptors are found in all organs
Major “Feel-Good” NT–Drugs that give a “high” can increase its effects in 3 ways:
1) Increase the amount released from presynaptic knob
2) Inhibit the MAO enzyme (that breaks it down in the synapse)
3) Block reuptake (reabsorption into presynaptic knob)
Brain makes less and less dopamine. (Why bother making any, there’s already too much?)
Addiction & Dopamine Dysregulation:
Hallucinogens often disrupt the serotonin system in the brain
What are some of the hallucinogens?
Serotonin
LSD, magic mushrooms, mescaline
Stroke– Brain damage occurs when a small number of dying neurons release their
glutamate, triggering cell-suicide in the surrounding neurons
Glutamate
Dopamine is depleted (runs out), several weeks are needed to produce enough for normal
functioning. Result is a “crash” of depression & anxiety.
Addiction & Dopamine Dysregulation
Lou Gehrig Disease—Excess glutamate causes death of motor neurons & severe muscle atrophy
Glutamate
Drug use is needed to experience pleasure but using also suppresses dopamine release even
more
Addiction & Dopamine Dysregulation
keep glutamate from binding to its receptors—
Causing “disconnected” feeling from self & reality, memory loss, pain & sensation loss,
hallucinations, trances
What are some of the drugs?
Dissociative Anesthetics
Cough suppressants, PCP, Ketamine
is toxic to neurons—literally ‘excited to death,’ causes ‘cell suicide’
Glutamate
So they not only block pain, they also give a natural “high,” which makes them much more effective pain killers & makes them addictive.
Opioid Painkillers
How does dopamine causes addiction (addictive behaviors).?
Dopamine turns on the ‘pleasure center’ of brain: This means that any activities (even just eating) that trigger the release of dopamine produce a feeling of pleasure that reinforces those activities/behavior.
