Unit 4 Day 3

Psychoactive or psychotropic drugs alter nervous system function, regardless of whether they are street drugs or prescription medications.
Drug activity takes place within the synapse, which is the fluid-filled space between the pre-synaptic axon terminals and post-synaptic dendrite receptors.

Agonist:
- Binds to dendrite receptor sites by mimicking the shape of natural neurotransmitters (such as nicotine mimicking acetylcholine or catecholamine).
- Agitates the receptor to trigger action potentials, causing an increase in neural and cellular activity.
Antagonist:
- Globs onto or covers dendrite receptor sites without activating them.
- Blocks actual neurotransmitters from connecting to receptors, causing neural activity to decrease.
Reuptake Inhibitor:
- Affects the pre-synaptic axon terminals by blocking the reabsorption ("vacuum") process of released neurotransmitters.
- Allows neurotransmitters to remain in the synapse longer to bind with receptors, causing neural activity to increase.

Drug classifications are determined by systemic effects on the Central Nervous System (CNS) and body, not by their specific synaptic mechanism.
Stimulants:
- Increase activity in the CNS, resulting in elevated heart rate, increased blood pressure, faster breathing, and reduced digestion.
- Examples: Caffeine (antagonist blocking adenosine), Nicotine (agonist), Cocaine (reuptake inhibitor), Amphetamines like Adderall, and Methylphenidate.
Depressants:
- Slow down CNS activity and body functions.
- Examples: Alcohol, Benzodiazepines (Xanax, Valium, Klonopin), and Barbiturates (commonly prescribed for seizures).
Opioids:
- Depress CNS activity at a higher intensity by targeting specific areas like the brainstem.
- Provide pain relief and euphoria.
- Examples: Heroin, Morphine, and Oxycodone.
Hallucinogens and Dissociatives:
- Alter perception of reality, time, and sense of self, and can remain in the system for long periods (e.g., causing flashbacks up to 30 years later).
- Examples: LSD, Psilocybin, PCP, and Ketamine.
Cannabis (THC):
- Categorized in its own distinct class due to highly concentrated modern forms that produce a mix of stimulating, depressing, or hallucinogenic properties.

Development of Dependence:
- Starts with behavioral dependence, where repeated thoughts and associations strengthen neural pathways via neuroplasticity.
- The brain's dopamine reward center reinforces the behavior each time a substance is used to solve a problem or relieve discomfort.
Tolerance and Physical Dependence:
- Extended drug use prompts the body to decrease its natural production of neurotransmitters to maintain equilibrium.
- Tolerance occurs when larger doses are required to achieve an equal baseline effect.
- Returning natural neurotransmitter production to baseline after stopping a substance typically takes about two years.
Definition of Addiction:
- Defined as continuous drug-seeking behavior despite severe negative life consequences.
- Driven by incentive sensitization, where neural pathways and cravings compel drug use even when the individual no longer desires the drug.

Question: Why does caffeine assist individuals diagnosed with ADD or ADHD?
- Response: Caffeine blocks rising adenosine levels to increase alertness and focus. As a side effect, it also elevates dopamine levels, helping compensate for natural neurotransmitter deficiencies related to executive functioning and attention.
Question: Why has the classification of cannabis changed over time?
- Response: Historically classified as a hallucinogen or depressant, cannabis is now placed in its own category because modern high-potency strains (e.g., up to 40% concentration compared to older 2% forms) produce varied effects across users.
Question: What synaptic mechanism allows Narcan to reverse an opioid overdose?
- Response: Narcan functions as an antagonist by physically blocking opioid receptors, preventing opioid molecules from binding and continuing their progression.