Brain, Nervous System, and Drugs

Vocabulary practice flashcards covering brain anatomy, neuronal function, action potential electrophysiology, neurotransmitters, drug action, and nervous system divisions based on Chapter 4 and 6 notes.

Grey Matter

Nervous tissue composed of neuron cell bodies, dendrites, and synapses that plays a crucial role in processing information.

White Matter

Nervous tissue composed of nerve fibers (axons), many surrounded by insulating myelin, that connects different areas of the nervous system together.

Central Nervous System (CNS)

The major control system consisting of the brain and spinal cord, where the spinal cord acts as the main pathway connecting the brain to the rest of the body.

Peripheral Nervous System (PNS)

The structural division of the nervous system outside the CNS, consisting of neurons with long axons and dendrites extending from the spinal cord to reaching the extremities.

Neuron

The fundamental building block of the nervous system responsible for transmitting information using a combination of electrical and kjemisk (chemical) signals.

Glial Cells

Non-neuronal cells in the nervous system that provide structural support, nutrient supply, and toxin removal for neurons, communicating through a separate network.

Dendrites

Specialized receiving structures on a neuron that collect incoming impulses and conduct them toward the cell body.

Soma (Cell Body)

The central part of a neuron containing the nucleus and biological machinery that keeps the cell alive and determines whether an electrical impulse will be generated.

Axon

A long nerve fiber that conducts electrical impulses away from the cell body toward other neurons, muscles, or glands.

Axon Terminals

Structures located at the end of an axon that send signals across synapses to target cells.

Myelin Sheath

A fatty layer produced by glial cells that wraps around and insulates the axon to speed up electrical message transmission; its degradation is seen in multiple sclerosis.

Resting Potential

The polarized membrane potential of a non-firing neuron, typically around $-70\,mV$, maintained by a higher concentration of sodium ions ($Na^+$) outside and potassium ions ($K^+$) inside.

Action Potential

A rapid, brief change in the neuron's electrical charge that propagates along the axon once the membrane potential reaches the threshold of approximately $-55\,mV$.

Depolarization

The phase of an action potential where $Na^+$ channels open and sodium ions flood into the cell, making the inside of the cell membrane briefly positive relative to the outside.

Repolarization

The phase of an action potential where $Na^+$ channels close and $K^+$ channels open, allowing potassium ions to exit the cell and restoring negative membrane potential.

Refractory Period

A brief recovery period following an action potential during which the neuron membrane is hyperpolarized and requires a short pause before it can fire another impulse.

Synaptic Cleft

The narrow gap separating the axon terminal of a presynaptic neuron from the dendrite or membrane of a postsynaptic neuron through which neurotransmitters diffuse.

Glutamate

The main excitatory neurotransmitter in the central nervous system, acting as an accelerator ("gas") for neural impulse generation.

GABA (Gamma-Aminobutyric Acid)

The primary inhibitory neurotransmitter in the central nervous system, serving as a brake to suppress nerve impulse firing.

Dopamine

A major neurotransmitter involved in regulating movement, reward processing, and motivation.

Serotonin

A key neurotransmitter involved in regulating sleep, appetite, and mood stability.

Norepinephrine

A neurotransmitter associated with physiological arousal, activation levels, and sustained attention.

Acetylcholine

A neurotransmitter involved in muscle contraction, as well as cognitive processes like learning and memory.

Endorphins

Endogenous neurotransmitters responsible for modulating pain perception and inducing feelings of pleasure or reward.

Agonist

A substance or drug that mimics or enhances the normal chemical activity of a neurotransmitter at its receptor site.

Antagonist

A substance or drug that blocks or decreases the biological effect of a neurotransmitter by binding to its receptor site without activating it.

Somatic Nervous System

The division of the peripheral nervous system responsible for voluntary muscle activation and somatic reflexes.

Autonomic Nervous System

The involuntary division of the peripheral nervous system controlling smooth muscle, cardiac muscle, and internal glands.

Sympathetic Nervous System

The branch of the autonomic nervous system that mobilizes the body for action during stress ("fight or flight"), dilating pupils, accelerating heartbeat, and inhibiting digestion.

Parasympathetic Nervous System

The branch of the autonomic nervous system responsible for calming the body and restoring homeostasis ("rest and digest"), slowing heart rate and stimulating digestive processes.

Endocrine System

A regulatory system of glands that works alongside the autonomic nervous system to release hormones directly into the bloodstream to regulate metabolism, stress, growth, and reproduction.

Contralateral Organization

The functional property of the brain where each cerebral hemisphere controls sensory and motor operations for the opposite side of the body.

Split-Brain Studies

Research conducted by Sperry and Gazzaniga on patients with a severed corpus callosum, demonstrating that the left and right hemispheres perform specialized independent functions.