Drugs Affecting the Nervous System: Central and Peripheral Nervous System

Comprehensive vocabulary flashcards covering anatomical divisions of the nervous system, neurotransmission mechanisms, and major central and autonomic pharmacology classifications.

Central Nervous System (CNS)

The main control center of the body consisting of the brain and spinal cord, responsible for processing sensory information, controlling voluntary and involuntary responses, and enabling higher functions such as cognition and memory.

Somatic Nervous System

The division of the peripheral nervous system that connects the central nervous system to skeletal muscles, controlling voluntary movements and transmitting sensory information from receptors to the CNS.

Autonomic Nervous System (ANS)

The division of the peripheral nervous system that regulates involuntary bodily functions by controlling smooth muscle, cardiac muscle, and glands to maintain homeostasis.

Sensory Nerves (Afferent Nerves)

Nerves that carry sensory input—such as touch, temperature, pain, and pressure—from receptors throughout the body to the central nervous system.

Motor Nerves (Efferent Nerves)

Nerves that transmit commands from the central nervous system to effector organs like muscles and glands to elicit movement or secretion.

Dendrites

Branch-like extensions of a neuron that receive incoming signals from other nerve cells and carry impulses toward the cell body (soma).

Axon

The long, slender projection of a neuron that conducts electrical impulses away from the cell body toward other neurons, muscles, or glands.

Myelin Sheath

A fatty protective covering around certain axons formed by Schwann cells in the PNS or oligodendrocytes in the CNS that accelerates signal transmission.

Synapse

The functional junction between two neurons (or between a neuron and an effector cell) where neurotransmitters transmit chemical signals across the synaptic cleft.

Glutamate

The primary excitatory neurotransmitter in the central nervous system that stimulates postsynaptic neurons to fire electrical signals.

Gamma-Aminobutyric Acid (GABA)

The primary inhibitory neurotransmitter in the central nervous system that decreases neuronal excitability and prevents postsynaptic action potentials.

Cerebrum

The largest portion of the brain, responsible for higher cognitive functions, sensory perception, voluntary movement, thinking, memory, and language.

Cerebellum

The brain structure that coordinates balance, posture, muscle tone, motor learning, and the fine-tuning of voluntary movements.

Brainstem

The connection between the brain and the spinal cord that regulates vital autonomic life functions, including respiration, heart rate, blood pressure, and arousal.

Ganglia

Clusters of nerve cell bodies situated outside the central nervous system that process and relay neural signals between the CNS and peripheral structures.

Enteric Nervous System

A network of neurons within the gastrointestinal tract wall that independently regulates gut motility, secretions, and local blood flow under autonomic modulation.

Diazepam

A benzodiazepine that enhances the inhibitory action of GABA by binding to the GABA-A receptor, increasing $Cl^-$ influx and hyperpolarizing the neuron to relieve anxiety, spasms, and seizures.

Phenobarbital

A barbiturate that produces central nervous system depression by enhancing GABA-A receptor activity and inhibiting excitatory neurotransmission.

Imipramine

A tricyclic antidepressant (TCA) that blocks the reuptake of norepinephrine and serotonin, thereby elevating their synaptic concentrations to treat depression, panic disorder, and enuresis.

Phenelzine

A monoamine oxidase inhibitor (MAOI) that blocks the enzymatic degradation of norepinephrine, serotonin, and dopamine, requiring strict avoidance of tyramine-rich foods to prevent hypertensive crisis.

Chlorpromazine

A first-generation typical antipsychotic that blocks dopamine $D_2$ receptors in the mesolimbic pathway, reducing psychotic symptoms like hallucinations and delusions.

Clozapine

A second-generation atypical antipsychotic that blocks dopamine $D_2$ and serotonin $5\text{-HT}_{2A}$ receptors for treatment-resistant schizophrenia, requiring regular blood monitoring for agranulocytosis.

Lithium

An antimanic mood stabilizer with a narrow therapeutic index that modulates serotonin, norepinephrine, and dopamine activity to prevent and treat manic episodes in bipolar disorder.

Methylphenidate

A central nervous system stimulant that inhibits dopamine and norepinephrine reuptake via DAT and NET, improving focus and impulse control in ADHD and narcolepsy.

Status Epilepticus

A life-threatening medical emergency characterized by continuous seizure activity or rapidly recurring seizures without recovery of consciousness between episodes.

Phenytoin

A hydantoin antiepileptic drug that inhibits voltage-gated sodium channels to stabilize neuronal membranes and prevent the spread of abnormal seizure discharges.

Ethosuximide

A succinimide antiepileptic medication that specifically treats absence seizures (petit mal) by blocking T-type calcium channels in thalamic neurons.

Valproic Acid

A broad-spectrum antiepileptic agent that elevates brain GABA levels and blocks voltage-gated sodium channels, contraindicated in pregnancy due to teratogenicity.

Parkinson's Disease

A neurodegenerative movement disorder caused by the progressive degeneration of dopamine-producing neurons in the substantia nigra, characterized by tremors, rigidity, and bradykinesia.

Biperiden

An anticholinergic (antimuscarinic) agent that reduces excessive central cholinergic activity relative to dopamine deficiency to alleviate tremors and rigidity in Parkinson's disease.

Levodopa

A metabolic precursor of dopamine that crosses the blood-brain barrier and is converted to dopamine to replenish depleted neurotransmitter stores in the basal ganglia.

Baclofen

A centrally acting muscle relaxant that activates $\text{GABA}_B$ receptors in the CNS to suppress excitatory neurotransmission and reduce muscle spasticity.

Dantrolene

A direct-acting skeletal muscle relaxant that treats spasticity and malignant hyperthermia by inhibiting calcium release from the sarcoplasmic reticulum inside muscle cells.

Morphine

A potent opioid agonist that binds to $\text{mu-opioid}$ receptors in the CNS to alter pain perception and produce analgesia, sedation, and euphoria.

Pentazocine

An opioid agonist-antagonist that acts as an antagonist at mu-opioid receptors and an agonist at kappa-opioid receptors to provide analgesia with reduced respiratory depression.

Naloxone

A pure opioid antagonist that competes for and displaces opioids at mu-opioid receptors, rapidly reversing opioid-induced respiratory depression in overdose.

Bethanechol

A direct-acting muscarinic cholinergic agonist that stimulates bladder detrusor contraction and gastrointestinal motility to treat nonobstructive urinary retention and ileus.

Atropine

A nonselective muscarinic cholinergic antagonist that blocks parasympathetic activity to treat symptomatic bradycardia, decrease secretions, and reverse cholinergic toxicity.

Tubocurarine

A non-depolarizing neuromuscular blocking agent that competitively blocks nicotinic acetylcholine receptors on the motor endplate, preventing muscle depolarization and causing flaccid paralysis.

Succinylcholine

A depolarizing neuromuscular blocker that causes initial receptor depolarization and muscle fasciculations followed by persistent binding that prevents repolarization, causing paralysis.

Lidocaine

An amide-type local anesthetic that blocks voltage-gated sodium channels in nerve fibers to inhibit the initiation and propagation of action potentials for local anesthesia and antiarrhythmic therapy.