Question

Describe the physiological effects and mode of action of alcohol, nicotine, cocaine, methamphetamine, heroin, and marijuana. (pages 295-98)

Short answer

Alcohol: Physiological effects include mild euphoria, relaxation, decreased inhibitions, and impaired motor function, memory, and decision-making. Its mode of action involves interacting with GABA receptors and inhibiting the neurotransmitter glutamate. Nicotine: Physiological effects comprise increased heart rate, blood pressure, alertness, and can improve memory/cognitive function. It acts on nicotinic acetylcholine receptors and stimulates neurotransmitter release. Cocaine: It causes increased alertness, energy, euphoria, blood pressure, heart rate, and body temperature. Cocaine inhibits the reuptake of dopamine, norepinephrine, and serotonin, increasing their synaptic cleft levels. Methamphetamine: Produces increased energy, alertness, and euphoria, but also severe physical and neurological damage. Its mode of action involves increasing the release of dopamine, norepinephrine, and serotonin while inhibiting their reuptake. Heroin: Creates euphoria, relaxation, pain relief, and depresses respiratory/nervous systems. It acts as an opioid agonist, binding to mu-opioid receptors, inhibiting pain signals, and releasing dopamine. Marijuana: Leads to relaxation, euphoria, altered perceptions, impaired memory, attention, and coordination. Its primary component, THC, acts on the endocannabinoid system by binding to CB1 and CB2 receptors, modulating neurotransmitter release.

Step-by-step solution

Alcohol: Physiological Effects

Alcohol consumption can lead to a range of physiological effects such as mild euphoria, relaxation, and a decrease in inhibitions. In higher concentrations, alcohol can impair motor function, memory, and decision-making. Long-term excessive consumption of alcohol can damage vital organs, including the liver, brain, and heart.

Alcohol: Mode of Action

Alcohol primarily acts by interacting with the gamma-aminobutyric acid (GABA) receptors in the brain. It enhances the neurotransmitter GABA's inhibitory effects, resulting in decreased neuronal excitability. Alcohol also inhibits the excitatory neurotransmitter glutamate, further contributing to its sedative effects.

Nicotine: Physiological Effects

Nicotine intake can lead to an increase in heart rate, blood pressure, and alertness. It has both stimulant and relaxant effects, and can cause a temporary improvement in memory and cognitive function. However, long-term use of nicotine can lead to addiction and a variety of health issues.

Nicotine: Mode of Action

Nicotine acts on the nicotinic acetylcholine receptors found in the brain and central nervous system. It mimics the neurotransmitter acetylcholine and stimulates the release of various neurotransmitters, such as dopamine, norepinephrine, and serotonin, which contribute to its stimulant and mood-enhancing effects.

Cocaine: Physiological Effects

The primary physiological effects of cocaine include increased alertness, energy, and euphoria. It also causes an increase in blood pressure, heart rate, and body temperature. Chronic use of cocaine can lead to heart damage, stroke, and mental health problems such as anxiety and depression.

Cocaine: Mode of Action

Cocaine's mode of action involves inhibiting the reuptake of certain neurotransmitters, namely dopamine, norepinephrine, and serotonin. This leads to an accumulation of these neurotransmitters in the synaptic cleft, which in turn enhances their effect on the postsynaptic neuron, resulting in increased stimulation and feelings of euphoria.

Methamphetamine: Physiological Effects

Methamphetamine use can lead to increased energy, alertness, and euphoria similar to cocaine. However, its effects last longer and can also cause severe physical and neurological damage, including tooth decay, weight loss, and cognitive decline.

Methamphetamine: Mode of Action

Methamphetamine primarily acts by increasing the release of dopamine, norepinephrine, and serotonin in the brain. It also inhibits their reuptake, which results in higher levels of these neurotransmitters in the synaptic cleft, contributing to its psychoactive effects.

Heroin: Physiological Effects

Heroin intake creates an intense sense of euphoria, relaxation, and pain relief. However, it also depresses the respiratory and nervous systems, which can lead to overdose and death. Long-term use can cause physical dependence and severe health problems such as collapsed veins, infections, and liver and kidney disease.

Heroin: Mode of Action

Heroin's mode of action is complex. It acts primarily as an opioid agonist, binding to the mu-opioid receptors in the brain. This binding results in the inhibition of pain signals and the release of dopamine, which leads to the pleasurable effects associated with heroin use. Heroin also impacts other neurotransmitter systems like serotonin and noradrenaline, contributing to its mood-altering effects.

Marijuana: Physiological Effects

Marijuana use can lead to relaxation, euphoria, and an altered perception of time and space. It can also impair memory, attention, and coordination. Long-term use can cause respiratory issues and may have negative effects on cognitive function and mental health.

Marijuana: Mode of Action

Marijuana's primary psychoactive component, THC (delta-9-tetrahydrocannabinol), acts on the endocannabinoid system in the brain by binding to the CB1 and CB2 receptors. This modulates the release of neurotransmitters, resulting in the various physiological effects observed with marijuana use.