Understanding Drugs: Effects, Types, and Neurotransmission
What are Drugs?
Drugs are substances that can cause dependence, stimulation, or depression of the central nervous system, leading to disruptions in judgment, behavior, or mood. In pharmacology and medicine, “drug” refers to the active ingredient used for treatment or prevention of diseases. However, socially, “drug” often denotes harmful, abused substances.
To be considered a drug, a substance must:
- Be introduced into a living organism and alter its functions.
- Lead to repeated use due to the pleasure it generates.
- Cause somatic or psychological discomfort upon cessation of use.
This term encompasses legal and illegal substances, including therapeutic drugs.
Synapses
A synapse is the communication link between brain cells. It begins with a chemical release causing an electrical discharge in the presynaptic cell. Neurotransmitters are then released into the synaptic space, exciting or inhibiting the postsynaptic neuron.
Synaptic Transmission
Neurotransmitters are diverse chemicals with significant implications for brain functions. Examples include:
- Acetylcholine and Noradrenaline: Key in the peripheral nervous system; noradrenaline also in the hypothalamus.
- Dopamine: Associated with motor activity; deficiency linked to Parkinson’s disease.
- Serotonin: Involved in sleep regulation.
- GABA: A major inhibitory neurotransmitter.
Drug Classifications
Depressants
Depressants, such as alcohol and barbiturates, can cause irritability and violent behavior. Withdrawal symptoms include insomnia, circulatory disorders, fever, convulsions, and potentially death.
Opiates (e.g., Morphine, Heroin)
- Effects: Euphoria, pain reduction, CNS depression, constricted pupils, impaired coordination.
- Risks: Tolerance, physical dependence, seizures, overdose.
Hypnotic-Sedatives (e.g., Barbiturates, Benzodiazepines)
- Effects: Sedation, anxiety reduction, CNS depression, slowed respiration and heart rate, reduced REM sleep.
- Risks: Physical dependence, respiratory depression.
Ethyl Alcohol (Ethanol)
- Effects: Euphoria, relaxation, impaired vision, coordination, and judgment.
- Risks: Physical dependence, organ damage, brain damage.
Inhalants (e.g., Toluene, Butane, Propane)
- Effects: General depression, relaxation, dizziness, headaches, nausea, slurred speech, loss of coordination.
- Risks: Psychological and physical dependence, severe organ damage, death.
Stimulants
Stimulants temporarily enhance physical abilities, behavior, and mood, often causing euphoria.
Cocaine
- Effects: Euphoria, excitement followed by depression, dilated pupils, local anesthesia.
- Risks: Seizures, hallucinations, unconsciousness, overdose.
Caffeine
- Effects: Increased alertness, reduced fatigue, smooth muscle relaxation, cardiac stimulation, diuresis.
- Risks: Seizures at high doses.
Nicotine
- Effects: Stress reduction, sympathetic nervous system stimulation, lipid synthesis in arterial walls.
- Risks: Tolerance, physical dependence, atherosclerosis.
Hallucinogens
Hallucinogens alter psychic functioning, causing sensory distortions and hallucinations.
LSD (Lysergic Acid Diethylamide)
- Effects: Sensory distortions, hallucinations, CNS stimulation, dilated pupils, increased heart rate and blood pressure.
- Risks: Irrational behavior.
Cannabinoids (e.g., Marijuana, Hashish)
- Effects: Euphoria, impaired coordination, altered depth perception and sense of time, eye inflammation, peripheral vasodilation.
- Risks: Sensory distortions, hallucinations, potential decrease in sperm count and testosterone levels.