MCAT Prep: Consciousness-Altering Drugs

Consciousness-Altering Drugs

aka psychoactive drugs described in four different groups: depressants, stimulants, opiates, and hallucinogens

Depressants

reduce nervous system activity, resulting in a sense of relaxation and reduced anxiety; include alcohol and sedatives

Alcohol

increases GABA receptor activity, can lead to disinhibition, increases dopamine levels; can effect logical reasoning, motor skills, and cause fatigue; alcoholism rates tend to be higher for those of lower socioeconomic status (SES) but they tend to enter recovery sooner and at higher rates

Disinhibition

a notable lack of self control associated with excessive consumption of alcohol, occurs because the centers of the brain that prevent inappropriate behavior are also depressed

Alcohol Myopia

inability to recognize consequences of actions, creating a short-sighted view of alcohol

GABA Receptor

a chloride channel that causes hyperpolarization of the membrane, hyperpolarization causes generalized brain inhibition at the physiological level resulting in diminished arousal at moderate doses

Long-Term Consequences of Alcoholism

include cirrhosis and liver failure, pancreatic damage, gastric/duodenal ulcers, gastrointestinal cancer, and brain disorders (including Wernicke-Korsakoff syndrome)

Sedatives

depress central nervous system, resulting in feelings of calm, relaxation, and drowsiness; increase GABA activity, highly addictive, can lead to coma/death if taken with alcohol and overdosed

Types of Sedatives

barbiturates and benzodiazepines

Barbiturates

historically used as anxiety-reducing (anxiolytic) and sleep medication, include amobarbital and phenobarbital

Benzodiazepines

less prone to overdose, have replaced many barbiturates; include alprarzolam, lorazepam, diazepam, and clonazepam

Stimulants

cause an increase in arousal in the nervous system, increases frequency of action potentials

Amphetamines

cause increased arousal by increasing release of dopamine, norepinephrine, and serotonin at the synapse and decreasing their reuptake, decreases appetite and need for sleep; increase heart rate and blood pressure, cause euphoria, hypervigilance, anxiety, delusions of grandeur, and paranoia, prolonged use of high doses can result in stroke or brain damage

Cocaine

originates from coca plant (grown in high-altitude regions of South America), can be purified from coca leaves or created synthetically; decreases reuptake on dopamine, norepinephrine, and serotonin synapses; has anesthetic and vasoconstrictive properties so is used in surgeries in highly vascularized areas (nose/throat), can lead to heart attacks/strokes when used recreationally; highly addictive

Crack

form of cocaine that can be smoked

Ecstasy (3,4-methylenedioxy-N-methylamphetamine, MDMA)

acts as hallucinogen combined with an amphetamine, causes increased heart rate + blood pressure, blurry vision, sweating, nausea, and hyperthermia; causes feelings of euphoria, increased alertness, and overwhelming sense of well-being and connectedness, club/rave drug, often packaged in colorful pills

Opiates and Opioids

types of narcotics (painkillers); derived from poppy plant, opium, create sense of euphoria, overdose can cause death by respiratory suppression

Opiates

naturally occurring forms of opium, include morphine and codeine

Opioids

semisynthetic derivates of opium; include oxycodone, hydrocodone, and heroin

Heroin

aka diacetylmorphine; once injected, body rapidly metabolizes heroin to morphine, usually smoked/injected, addiction treatment may include use of methadone

Methadone

long-acting opioid with lower risk of overdose

Hallucinogens

drugs which typically cause introspection, distortions of reality + fantasy, and enhancement of sensory experiences; cause increased heart rate + blood pressure, dilation of pupils, sweating, and increased body temperature; include lysergic acid dietyhlamide (LSD)

Marijuana

refers to leaves and flowers of two plant species: Cannabis sativa and Cannabis indica; falls into categories of stimulant, depressant, and hallucinogen

Tetrahydrocannabinol (THC)

active chemical in marijuana; acts on cannabinoid receptors, glycine receptors, and opioid receptors, inhibits GABA activity and indirectly increases dopamine activity; physiological effects include eye redness, dry mouth, fatigue, impairment of short-term memory, increased heart rate, increased appetite, lowered bp

Mesolimbic Reward Pathway

related to drug addiction; includes nucleus accumbens (NAc), ventral tegmental area (VTA), and connection between them called the medial forebrain bundle (MFB); normally involved in motivation and emotional response, activation accounts for positive reinforcement of substance use, activated by all substances that produce psychological dependence; gambling and falling in love activate this pathway