Bio 36: Drugs and the Brain - Exam I Study Guide

Comprehensive practice flashcards for Bio 36 covering neuroanatomy, autonomic and somatic nervous systems, neurotransmission mechanisms, pharmacological history, behavioral paradigms, and synthetic drug trafficking.

What anatomical structures make up the central nervous system (CNS) versus the peripheral nervous system (PNS)?

The central nervous system includes the brain and spinal cord, whereas the peripheral nervous system encompasses all nerves located outside of the central nervous system.

What are the four major lobes of the cerebral cortex and their primary functions?

The four lobes are: the Frontal Lobe (high-level decision-making, motor execution via the primary motor cortex, and speech production); the Parietal Lobe (somatosensory processing for touch, pressure, and taste via the primary somatosensory cortex); the Occipital Lobe (visual processing via the primary visual cortex and association areas); and the Temporal Lobe (hearing, smell, and auditory association).

What are the brain ventricles, what fluid fills them, and why do they have a curved shape?

The ventricles are hollow interconnected cavities filled with cerebrospinal fluid (CSF) that assist in removing waste from the brain's high metabolic activity. They are curved around the brain due to the developmental constraints imposed by the birth canal.

How do the primary motor cortex and primary somatosensory cortex differ in function and cortical location?

The primary motor cortex is situated in the frontal lobe and is responsible for planning, controlling, and executing voluntary muscle movements. The sensory (somatosensory) cortex resides in the parietal lobe and receives and interprets sensory inputs such as touch, pressure, vision, hearing, taste, and smell.

What functional roles are played by the limbic system, the hippocampus, and the amygdala?

The limbic system governs emotions and memory. The anterior cingulate maps to emotions; the amygdala mediates emotionally charged "fight or flight" responses and detects facial expressions; and the hippocampus processes memory and actively inhibits amygdala overactivation.

What is the primary function of the basal ganglia in motor control?

The basal ganglia regulates smooth muscle movements before motor commands are dispatched from the cortex, collaborating with the cerebellum through muscle memory.

How do gray matter and white matter differ compositionally and functionally in the CNS?

Gray matter consists of dense neuronal cell bodies, dendrites, and synapses where neuronal communication occurs, appearing darker in tone. White matter consists of myelinated axon tracts and projections connecting distinct regions and hemispheres, which are insulated by oligodendrocytes (such as the corpus callosum).

What is a brain "nucleus" in the context of neuroanatomy?

A nucleus is a localized cluster of neuronal cell bodies that produce the same type of neurotransmitter and send long axon projections along specific pathways to defined terminal regions.

How do the distribution patterns of dopamine, serotonin, norepinephrine, and acetylcholine compare to GABA and glutamate?

Dopamine, serotonin, norepinephrine, and acetylcholine originate from large, discrete groupings of nuclei that send long projections across the brain, whereas GABA and glutamate are widespread throughout virtually all brain regions.

How do afferent signals differ from efferent signals in the nervous system?

Afferent pathways convey sensory information toward the brain/CNS for processing and interpretation, whereas efferent pathways convey motor signals away from the CNS to control effectors such as skeletal muscles.

How do the somatic and autonomic nervous systems differ in function?

The somatic nervous system controls voluntary skeletal muscle movement and conscious sensory perception (using nicotinic acetylcholine receptors at neuromuscular junctions), while the autonomic nervous system regulates involuntary visceral functions outside conscious awareness, such as smooth muscle, cardiac muscle, and glandular secretion.

What are the two major divisions of the autonomic nervous system and their primary physiological roles?

The sympathetic division drives the "fight or flight" response (accelerating heart rate, dilating pupils, relaxing bronchi, and heightening vigilance), while the parasympathetic division mediates the "rest and digest" state (slowing heart rate, stimulating salivation and digestion, and constricting pupils and bronchi).

What neurotransmitters and receptor types are utilized by the preganglionic and postganglionic fibers of the sympathetic versus parasympathetic nervous systems?

Both sympathetic and parasympathetic preganglionic fibers release acetylcholine ($\text{ACh}$) onto nicotinic receptors ($\text{Nic}$). Parasympathetic postganglionic fibers release $\text{ACh}$ onto muscarinic receptors ($\text{Musc}$), whereas sympathetic postganglionic fibers release norepinephrine ($\text{NE}$) onto adrenergic ($\alpha$ and $\beta$) receptors.

What discovery did Otto Loewi make regarding chemical synaptic transmission?

Otto Loewi discovered chemical neurotransmission by isolating frog hearts and identifying "Vagusstoff" (acetylcholine, which slows cardiac rate) and "Acceleransstoff" (which accelerates cardiac rate).

What sequence of events occurs at the neuromuscular junction to trigger muscle contraction?

An action potential invades the axon terminal, opening voltage-gated $Ca^{2+}$ channels; incoming $Ca^{2+}$ triggers exocytosis of acetylcholine ($\text{ACh}$); $\text{ACh}$ binds to nicotinic receptors on the motor end plate, gating an influx of $Na^+$ to propagate a muscle action potential; acetylcholinesterase subsequently degrades $\text{ACh}$.

What is the function of the vesicular monoamine transporter (VMAT)?

VMAT is a transport protein that pumps monoamine neurotransmitters from the presynaptic cytoplasm into synaptic vesicles, preparing and concentrating them for exocytosis.

What is the biochemical role of monoamine oxidase (MAO)?

MAO is an intracellular enzyme that catalyzes the oxidative degradation and catabolism of monoamines, including dopamine, norepinephrine, and serotonin ($5\text{-HT}$).

What is meant by neurotransmitter release occurring in "quanta"?

Neurotransmitters are pre-packaged within individual synaptic vesicles; upon depolarization and $Ca^{2+}$ influx, vesicles fuse to release standardized, multi-molecular packets called quanta into the synaptic cleft.

How do ionotropic receptors differ fundamentally from metabotropic receptors?

Ionotropic receptors are ligand-gated ion channels composed of multiple interchangeable subunits that exhibit fast, all-or-none on/off kinetics. Metabotropic receptors are monomeric transmembrane proteins coupled to intracellular G-proteins and second messengers that act more slowly, but can amplify or dampen signals and trigger diverse cellular responses.

What is the difference between temporal summation and spatial summation in post-synaptic neurons?

Temporal summation occurs when a single presynaptic neuron fires at high frequency in rapid succession at one synapse, adding EPSPs over time. Spatial summation occurs when multiple presynaptic terminals fire simultaneously at different spatial locations across the postsynaptic neuron's dendrites or soma.

How are anabolism, catabolism, and first-order metabolism defined in pharmacology?

Anabolism is the energy-consuming synthetic phase that builds complex molecules (e.g., proteins, DNA); catabolism is the breakdown phase that degrades nutrients into smaller units to release energy as ATP; first-order metabolism describes the clearance of a constant percentage of a drug per unit of time.

Why is drug classification based strictly on chemical structure problematic?

Subtle changes in chemical structure can completely alter pharmacological profiles (e.g., methamphetamine versus MDMA), while chemically disparate molecules (such as cocaine and amphetamine) can produce very similar stimulant actions and behavioral phenotypes.

What is psychopharmacology, and why are standardized rating scales utilized in human psychopharmacological trials?

Psychopharmacology is the study of how chemical substances alter mind, mood, behavior, and neural function. Rating scales (such as HAM-D for depression and HAM-A for anxiety) are used to convert subjective mental and emotional states into standardized, measurable, and comparable numerical data.

What is Ronald K. Siegel's "universal fourth drive" hypothesis regarding intoxication?

The hypothesis posits that the motivation to seek out substances with mood-altering properties is a universal biological drive found widely throughout the animal kingdom, ranking fourth after hunger, thirst, and sex.

What psychoactive mushroom was historically consumed by Viking Berserkers, and what active compounds does it contain?

Amanita muscaria (fly agaric), which contains the psychoactive compounds muscimol and muscarine.

What three classic plants constitute the anticholinergic ingredients of "Witches' Brew," and which alkaloids do they contain?

Mandrake (containing scopolamine), henbane (containing hyoscyamine), and belladonna (containing atropine).

What plant produces mescaline, and what are its prominent psychological effects?

The peyote cactus; it produces vivid open- and closed-eye colored visual imagery, altered time perception, and mood alteration, historically used in religious and social ceremonies.

What is "Teonanacatl," and what archaeological evidence indicates its historical use in Mesoamerica?

Teonanacatl (Nahuatl for "food of the gods") refers to psilocybin-containing mushrooms. Its sacramental use is evidenced by approximately $200$ carved mushroom stones dating back $3,500$ years in Guatemala, often found alongside metates used for grinding.

What is the earliest recorded civilization to document opium, and what name did they give it?

Ancient Sumeria in approximately $5000\text{ BC}$, where the opium poppy was referred to as the "joy plant."

What archaeological evidence at Göbekli Tepe in Turkey connects drug production with the origin of agriculture?

The discovery of an $11,000$-year-old beer brewing site at Göbekli Tepe suggests that alcohol fermentation and communal consumption may have driven Neolithic agricultural development.

What work did Sigmund Freud publish on cocaine in $1884$, and what applications did he investigate?

Freud published "Über Coca", investigating cocaine's effects on fatigue, clinical depression, physical strength, and its potential as a treatment for morphine addiction.

When was cocaine introduced into Coca-Cola by John Pemberton, and when was it removed?

John Pemberton included cocaine as a main ingredient in $1886$; it was removed and banned from the beverage in $1903$.

What key United States federal drug statutes were enacted in $1906$ and $1914$?

The Pure Food and Drug Act of $1906$ established consumer labeling requirements, and the Harrison Narcotics Tax Act of $1914$ instituted federal taxation and regulation of opiates and cocaine.

How was Chlorpromazine ($4560\text{RP}$) accidentally discovered, and what significance did it have in psychiatry?

Developed in the early $1950\text{s}$ as an antihistamine, chlorpromazine was observed to calm psychotic symptoms in patients with schizophrenia, becoming the first effective antipsychotic medication and igniting the modern psychopharmacological revolution.

Who first synthesized LSD ($\text{lysergic acid diethylamide}$), when, and from what precursor?

Albert Hofmann synthesized LSD in $1938$ from ergotamine, an alkaloid derived from the ergot fungus.

What Harvard experiments led by Timothy Leary and Richard Alpert explored psychedelic compounds before their dismissal?

The Harvard Psilocybin Project, the Concord Prison Experiment, and the Marsh Chapel Experiment.

What four basic operant reinforcement schedules were defined by B. F. Skinner?

Fixed Interval (FI: reinforcement after a fixed duration), Variable Interval (VI: reinforcement after variable average time), Fixed Ratio (FR: reinforcement after a fixed count of responses), and Variable Ratio (VR: reinforcement after an unpredictable, average number of responses, yielding the highest response rates).

What apparatus did B. F. Skinner develop to study operant conditioning and schedule-controlled behavior?

An operant conditioning chamber (or Skinner box), containing manipulanda such as response levers, signal lights, pellet dispensers, and an electric shock grid.

How does the rodent Forced Swim Test evaluate potential antidepressant compounds?

Rats or mice are placed into an inescapable cylinder of water; effective antidepressant drugs significantly prolong active swimming and climbing behaviors while delaying or reducing immobility.

What behavioral assay is depicted here, and how does it index rodent anxiety?

The open field test; it assesses anxiety by measuring the rodent's natural preference for remaining near the periphery/walls (thigmotaxis) versus venturing into the illuminated open center area.

What animal testing paradigm is shown here, and how does it detect anxiolytic drug activity?

The elevated plus maze; anxiolytic medications increase the time rodents spend exploring and entering the open, unprotected arms relative to the sheltered closed arms.

What motor function is assessed using the rotarod apparatus?

Motor coordination, balance, and drug-induced ataxia (incoordination), quantified by the duration an animal balances on a rotating cylinder.

Who discovered in $1949$ that lithium salts effectively control mania in bipolar disorder?

The Australian physician John Cade.

What is the biosynthetic pathway and required enzymes for catecholamine synthesis from phenylalanine?

Phenylalanine $\rightarrow$ L-Tyrosine (via Phenylalanine Hydroxylase) $\rightarrow$ L-DOPA (via Tyrosine Hydroxylase) $\rightarrow$ Dopamine (via L-Aromatic Amino Acid Decarboxylase) $\rightarrow$ Norepinephrine (via Dopamine $\beta$-Hydroxylase) $\rightarrow$ Epinephrine (via Phenylethanolamine N-Methyltransferase).

What is the biosynthetic pathway for serotonin synthesis from dietary tryptophan?

L-Tryptophan is converted to $5\text{-Hydroxy-L-tryptophan}$ ($5\text{-HTP}$) by tryptophan hydroxylase, which is subsequently converted to serotonin ($5\text{-HT}$) by aromatic L-amino acid decarboxylase.

How do synthetic drugs differ fundamentally from naturally occurring drugs in production, cost, and trafficking?

Synthetic drugs are manufactured chemically without relying on agricultural land, specific climates, or multi-year crop growth cycles, requiring minimal space and completing synthesis in hours. This enables lower production costs, higher purity, easy structural modification, and vastly higher potency, making them easier to conceal and traffic.

What are three operational advantages of illicitly trafficking precursor chemicals over finished drugs?

1. Limited regulatory oversight and fewer legal restrictions compared to finished controlled substances; 2. Sourcing through online commercial platforms without alerting authorities; 3. Ready global availability at substantially lower procurement and manufacturing costs.

What is meant by "enhanced synthesis routes" in illicit drug manufacturing?

Simplifying and streamlining chemical reaction steps so that synthetic drugs can be mass-produced with minimal labor by operators who lack formal training in chemistry.

Why does the extreme potency of synthetic drugs like fentanyl make interdiction challenging?

Because fentanyl is approximately $50$ times more potent than heroin, tiny physical quantities fulfill immense consumer demand, allowing the drug to be easily concealed in micro-parcels across normal postal channels or individual couriers.

What are the commercial benefits and health risks of mixing diverse diluents and adulterants into street drugs?

Benefits include altering psychoactive profiles, increasing perceived potency, mimicking brand-name drugs at cheaper costs, and targeting niche demographics; risks include severe, unpredictable toxicities, overdoses, and fatal medical complications due to undisclosed chemical additives.