How drugs affect the brain’s Central Nervous System

Blocking Neurotransmitters: Other drugs, like antagonists, work by blocking receptors. For example, some anti-anxiety drugs prevent certain neurotransmitters from binding to their receptors, which calms the nervous system.

Altering Neurotransmitter Release or Reuptake: Drugs can also increase the amount of neurotransmitters released into the synapse or block their reabsorption. For instance, stimulants like cocaine block the reuptake of dopamine, a neurotransmitter associated with pleasure. This causes a massive buildup of dopamine in the synapse, overstimulating the neurons and producing the intense feeling of euphoria.

Technical Term from Chapter 3: Synaptic Vesicle

A key technical term to understand is the synaptic vesicle. Synaptic vesicles are tiny, membrane-bound sacs located in the axon terminal of a neuron. Their primary function is to store neurotransmitters. When an electrical signal, or action potential, travels down the neuron, it triggers the synaptic vesicles to fuse with the cell membrane, releasing their neurotransmitters into the synaptic cleft. The neurotransmitters then cross the synapse to bind with receptors on the next neuron, continuing the signal. Drugs can directly target this process; for example, some stimulants cause synaptic vesicles to release neurotransmitters like dopamine and norepinephrine even without a signal, leading to the "rush" associated with their use.

Sample Answer

Drugs affect the brain's Central Nervous System (CNS) by altering the way nerve cells, or neurons, send, receive, and process information. They do this by either mimicking or blocking the actions of the brain's natural chemical messengers, called neurotransmitters. This interference disrupts normal brain function, leading to the effects associated with drug use, from feelings of euphoria to changes in mood and behavior.

How Drugs Interfere with Neurotransmitters

The brain's communication system relies on neurotransmitters, which travel across tiny gaps called synapses to transmit signals from one neuron to another. Drugs can manipulate this process in a few ways:

Mimicking Neurotransmitters: Some drugs, such as opioids and marijuana, are chemically similar to natural neurotransmitters like endorphins and anandamide. They can bind to the brain's receptors and activate neurons in a way that mimics the natural chemicals, often resulting in an exaggerated response, such as intense feelings of pleasure.