The Influence of Drugs on Neurotransmitters

Action potential

Occurs when a neuron sends information down an axon, away from the cell body. Neuroscientists use others words, such as a spike or an impulse. An explosion of electrical activity that is created by a depolarizing current.

Axon terminal

The very end of a branch of a nerve's axon, a long slender nerve fiber that conducts electrical signals to a nerve synapse (the gap between nerve cells). The signal then moves across the synapse to another axon by means of a neurotransmitter.

Neurotransmitters

A chemical substance that is released at the end of a nerve fiber by the arrival of a nerve synapse or junction, causes the transfer of the impulse to another nerve fiber, a muscle fiber, or some other structure.

Synapse

A junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter.

Dendrites

Branchlike parts of a neuron that are specialized to receive information.

Dopamine

A neurotransmitter associated with movement, attention and learning and the brain's pleasure and reward system.

Reuptake

A process in which neurotransmitters are sponged up from the synaptic cleft by the presynaptic membrane.

Agonists

Drugs that increase the action of a neurotransmitter

Morphine

Example of an agonist.

Endorphins

morphine within"--natural, opiate-like neurotransmitters linked to pain control and to pleasure.

Antagonists

Chemical substances that block or reduce a cell's response to the action of other chemicals or neurotransmitters.

Atropine

Example of antagonist

Reuptake Inhibitor

Chemical that binds to the terminal buttons and prevents reuptake, thereby causing an excess of that NT

Cocaine

Example of reuptake inhibitor.

Amphetamine

A central nervous system stimulant that is used in the treatment of attention deficit hyperactivity disorder, narcolepsy, and obesity.

Substance use disorder

Essential feature of a _____________ is a cluster of cognitive, behavioral, and physiological symptoms indicating that the individual continues using the substance despite significant substance related problems.

Synaptic cleft

The space between neurons at a nerve synapse across which a nerve impulse is transmitted by a neurotransmitter. Also called a synaptic gap.

Memories

One of the things that lasts the longest is the ________________ associated with drug use and drug abuse.

100 tillion

# of synapses in the brain

50%

_________ of the risk for addiction is genetic.

Nicotine

Has been shown as a precursor for cocaine and methamphetamine use.

25%-30%

_____ of people who get exposed to heroine will become addicted. This has the highest addiction rate.

21 million

_________ people in the US have the disease of addiction.

15 million

_______ alcohol related addictions.

3 million

_______ opioid related addictions.

Treatments for craving

Lack of dopamine, augentation, buprenorphine and methadone increase dopamine, stabilizes craving, effective behavioral therapy.

ASAM criteria

A collection of objective guideline that gives clinicians a way to standardize treatment planning and where patients are placed in treatment, as well as how to provide continuing, integrated care and ongoing service planning.

Dr. William Silkworth

80 years ago, __________________ suggested that alcoholism (addiction) came from a combination of an obsession of the mind coupled with an allergy/illness of the body.
These observations have been validated by modern neuroscience.
Over the years, drug abu

Psychoactive drugs

Directly affect the neurochemistry and anatomy of the CNS, causing mental, emotional, and physical changes.

Pharmacokinetics

The process by which a drug is absorbed, distributed, metabolized, eliminated, and excreted

Pharmacokinetics

The key factors in _____________:
Route of administration
Speed of transit to the brain
Rate of metabolism
Process of elimination
Affinity for nerve cells and neurotransmitters.

Rapidly

The more ___________ a psychoactive drug reaches its target in the CNS, the greater its reinforcing (Addictive) effect.

Common ways drugs enter the body

Inhalation
Injection
Mucous membrane absorption
Oral ingestion
Contact absorption.

Blood brain barrier

A drug will reach the gateway to the central nervous system.

Bloodstream

Regardless of how a drug enters the system, it is eventually distributed by the ___________ to the rest of the body.

Metabolosim

The body's mechanism for processing, using, and inactivating a substance.

Excretion

The process of eliminating the substance and its metabolites from the body.

Liver

The ________ is the key metabolic organ, it breaks down or alters the chemical structure of drugs.

Kidneys

The ___________ are the primary excretory organs.

Half life

A drug's ___________ is a measure of time it takes for half the dose to be inactivated or eliminated.

Autonomic system

Controls involuntary internal functions such as circulation, respiration, digestion, etc.

Somatic system

Transmits sensory information about the environment and limb and muscle position; transmits instructions from the CNS back to the muscles, allowing the body to respond appropriately.

Central Nervous System

Comprises the brain and spinal cord.

Central Nervous System

Receives messages from the PNS, analyzes them, and then sends responses.

Central Nervous System

Enables us to remember, reason, create, think, to respond.

Central Nervous System

Psychoactive drugs can alter the information sent to the brain from the environment.

Old brain

Consists of brainstem, cerebellum, and mesocortex (mid brain), which contain the limbic system.

Old brain

Regulating physiological functions of the body (respiration, heartbeat, temperature, hormone, release, muscles).
Experiencing basic emotions and cravings (anger, fear, hunger, thirst, lust, pain, pleasure).
Imprinting survival memories (that tastes good,

New brain (neocortex)

Processes information coming from the old brain, from different areas of the new brain, and from senses via the PNS.
Allows us to speak, reason, create, remember, make decisions, and then act, while the old brain simply reacts.
Craving can override the ne

Survival/reinforcement circuit Go Switch

The area of the brain that encourages a human to perform or repeat an action that promotes survival.
Its normal function is to reinforce an action that promotes survival.
This part of the brain is most affected by psychoactive drugs.
This survival/reinfor

Survival/reinforcement circuit Go Switch

Normally, the go switch does three things when activated:
Tells us what we are doing is necessary for survival, giving us a feeling of satisfaction.
Tells us to remember what we did to survive.
Then tells us, "Do more of whatever you did-do it again and a

Stop switch

Located mostly in the new brain.
When the need has been satisfied, the stop switch shuts down the go switch and the do ti again message ceases.
This signals the cells to stop releasing dopamine, which shuts down these messages.

Hijacking

When a psychoactive drug actives this pathway, the result is a feeling of satisfaction, a high, or pain relief, which prompts the go switch to urge the person to do it again, do it again.
For substance abusers who have altered brain chemistry, the go swit

Hijacking

The survival/reinforcement and control circuits have been _________, so the individual continues to use drugs, tricked into sensing that survival depends on it.
As chronic heavy use continues and the neurochemistry changes, the do it again message becomes

Hijacking

The stop switch is often totally disabled by chronic drug use, rendering it useless to stop even a mild craving from turning into drug use.
The overriding message at a subconscious level is if you don't do it again, you will die.

Go switch/stop switch

In a person with addiction, the ________ switch is overactive and the ___________ switch is either underactive or unable to communicate the shut it down message back to the survival/reinforcement circuit, so the brain is stuck in a do it again more.

Fasciculus retroflexus

Due to damage of the _________________, which can occur very early in chronic drug use; young people who drink heavily can damage this nerve pathway after just a few binges.

Reflex

An immediate reaction triggered by the old brain.

Dendrites

Receive signals from other nerve cells and relay them through the cell body.

Cell body

Nourishes the cell and keeps it alive.

Axon

Carries the message from the cell body to the terminals.

Terminals

Relay messages to the dendrites, cell body, or terminals of the next nerve cell.

Vesicles

The neurotransmitters are stored in tiny sacs called ___________ that travel through the neuron to the axon terminals.

Action potential

If enough synapses collectively create enough ______________ in the next nerve cell, the electrical charge can travel to the next synapse where it is again converted into a chemical signal for the next synapse.

Endogenous opioids

Endorphins and enkephalins are called __________, this means they are produced by the body.

Exogenous opioids

Morphine, heroin, and other opium derivatives or synthetics are called _______________, this means they are produced externally from the body.

Monoamines

Includes dopamine, which is the most crucial neurotransmitter involved in both substance and process addictions, the reward chemical.
Includes serotonin, which helps control mood stability.

Opioids peptides

Related to pain

Four groupings of major neurotransmitters

Monoamines
Amino acids
Opioid peptides
Miscellaneous.

Message transmission

Occurs when the incoming electrical signal forces the release of neurotransmitters from the vesicles.
This sends them across the synaptic gap.
On the other side of the gap, the neuro transmitters slot into precise and complex receptor sites.
These recepto

Message transmission

Excitatory neurotransmitters increase cell firings by opening the gate and allowing positive ions into the neuron.
Inhibitory neurotransmitters reduce cell firings by allowing negative ions into the neuron, pushing positive ions out.
When enough excitator

Reabsorbed

As neurotransmitters complete their job, they are released back into the synaptic gap and are _________ by the sending nerve cell reuptake ports and returned to the vesicles, ready to fire again.

Autoreceptors

The amount of neurotransmitters available for message transmission is constantly monitored by _____________ on the sending neuron.

Down regulation

If there are too many neurotransmitters, it retracts many of the receptor sites, slowing down the message transmission. Excessive use can cause a permanent decrease in receptor sites.

Up regulation

If there are too few neurotransmitters available to trigger the message, the receiving neuron will increase the number of receptor sites to provide the few remaining neurotransmitters with more receptors to active.

Agonists

Drugs that bind to receptors and mimic or facilitate the effects of neurotransmitters are called ________.

Antagonists

Drugs that bind to receptors but don't activate them, thereby blocking neurotransmitters are called _________

Partial agonists

Drugs that bind to receptors and partly mimic the effects of neurotransmitters are called ____________

Inverse agonists

Drugs that bind to receptors and stabilize the receptor in its inactive state by hyperpolarizing it so that it cannot react are called_________

Heroin

Block release of neurotransmitters from vesicles.

Cocaine

Force release of neurotransmitters by entering the presynaptic neurons, causing more to be released than naturally.

Antidepressants

Prevent neurotransmitters from being reabsorbed into the sending neuron, causing them to remain in the synapse to slot into receptors agin, inducing more intense effects.

Heart meds

Inhibit enzyme that helps synthesize neurotransmittesr to slow the nerve cell's production of neurotransmitters.

Tissue dependence

Results from biological adaptation of the body due to prolonged use of a drug. The tissues and organs become dependent on the drug simply to stay functional.

Categories to judge a person's level of use

Abstinence
Experimentation
Social/recreational sue
Habituation
Abuse
Addiction

Addictive disease model

Disease of addiction is a chronic, progressive, recurring, incurable, and potentially fatal condition that is generally a consequence of genetic irregularities in brain chemistry and anatomy that may be activated by the particular drugs.

Behavioral/environmental model

Emphasizes environmental and developmental influences.
Environmental factors can change brain chemistry.

Academic model

The body adapts to the substance sin order to achieve homeostasis, which reinforces addiction.

Diathesis-stress theory of addiction

Combination
Predisposition to addiction as a result of genetic and environmental influences, which, when further stressed by the use of substances or engaging in certain behaviors, alters neurochemistry, brain function, and even epigenetics to the point t