The Nervous System

Comprehensive vocabulary flashcards covering the human nervous system, neuronal physiology, brain anatomy and function, action potentials, synapses, axonal transport, and the endocannabinoid system.

Central Nervous System (CNS)

The major division of the nervous system consisting of the brain (including the retinas) and the spinal cord.

Peripheral Nervous System (PNS)

All neurons situated outside the central nervous system, consisting of 31 pairs of spinal nerves and 12 pairs of cranial nerves.

Neuron

The basic cellular unit of the nervous system, occurring in motor and sensory types, unipolar, bipolar, or multipolar forms, and consisting of axons, dendrites, and a soma or cell body.

Dendrite

The part of a neuron that receives stimuli and carries them to the cell body.

Soma (Cell Body)

The central region of a neuron that serves as the site of cellular activity.

Axon

A neuronal projection that carries nerve impulses away from the cell body toward one or several termini, transmitting an electrochemical signal.

Schwann Cells

A type of glial cell that wraps continuously around the axon of certain neurons, appearing as multiple lipid-protein layers.

Myelin

A protective covering formed by Schwann cells wrapping around axons in multiple lipid-protein layers, functioning to increase the speed of action potential conduction.

Nodes of Ranvier

Gaps located between adjacent Schwann cells along an axon that facilitate rapid conduction by allowing impulses to jump from node to node.

Saltatory Conduction

The mode of nerve impulse transmission along myelinated axons in which the action potential jumps from one Node of Ranvier to the next, increasing conduction speed.

Na+ / K+ Pump

A membrane-bound protein complex that utilizes ATP to move sodium out of the cell and potassium in, maintaining resting membrane potential and establishing ion concentration gradients.

Resting Membrane Potential

The electrical charge difference between the interior and exterior of a cell characterized by greater external $Na^+$ concentration, greater internal $K^+$ and anion concentration, and higher membrane permeability for $K^+$ than $Na^+$.

Irritability

The functional nerve property that enables a neuron to respond to stimuli.

Conductivity

The functional nerve property that enables a neuron to transmit an electrical potential along its axon.

Voltage-Gated Na+ Channel Conformations

The three sequential physical states of the sodium channel during an action potential: closed in the polarized state, open upon depolarization, and inactivated during depolarization before repolarization returns it to closed.

Cerebrum

A major division of the brain consisting of the cerebral cortex (telencephalon) and the diencephalon.

Cerebral Cortex

The gray matter surface of the cerebrum lacking white myelin coating that governs intellectual processes (thought, intelligence) and integrates sensory input with past experience to produce motor responses.

Lobes of the Cerebral Cortex

The four primary functional divisions of the cerebral cortex: the frontal lobe, parietal lobe, temporal lobe, and occipital lobe.

Diencephalon

A core region of the cerebrum composed principally of the thalamus and hypothalamus.

Thalamus

A diencephalon structure that relays sensory stimuli to the cortex, routes cerebral cortex output to appropriate processing areas, and regulates sleep, consciousness, and alertness.

Hypothalamus

A diencephalon structure that helps maintain homeostasis by monitoring temperature, blood glucose, and hormone levels, controlling hunger, fatigue, and sleep, and signaling both the pituitary and lower neural centers.

Hippocampus

A brain structure that plays a vital role in regulating learning, memory encoding, memory consolidation, and spatial navigation, whose function is altered by THC.

Basal Ganglia

Subcortical brain nuclei responsible for the control of movements, learning, habit formation, cognition, and emotion.

Amygdala

A brain structure responsible for processing memory, decision-making, and emotional responses.

Cerebellum

A brain structure located behind the brainstem that monitors movement and integrates postural adjustments, equilibrium, perception of speed, and fine-tuning reflexes.

Brainstem

A brain region composed of the midbrain, pons, and medulla oblongata that mediates autonomic reflexes and maintains vegetative functioning, including respiratory and cardiovascular control centers.

Spinal Cord

A central nervous system structure protected by vertebrae and continuous with the brainstem, featuring white matter surrounding an H-shaped gray matter core from which peripheral nerves exit.

Somatic Afferent Nerves

Sensory nerve fibers that convey sensations (such as pain, temperature, and touch) as well as proprioceptive signals from the periphery back to the spinal cord.

Somatic Efferent Nerves

Motor nerve fibers that communicate impulses from the spinal cord outward to skeletal muscles.

Motor Unit

The functional unit of movement, consisting of a single motor neuron and all of the muscle fibers that it innervates.

Synapse

The junction between the axon terminal of one neuron and the dendrites of another where communication occurs through the release of chemical neurotransmitters.

All or None Law

The principle stating that if a neuron reaches threshold, it fires an action potential that traverses the entire axon without voltage loss, causing all innervated muscle fibers to contract; if threshold is not met, no firing occurs.

Axonal Transport

The bidirectional cellular mechanism by which nerve cells deliver thousands of cargo substances along microtubules between the cell body and the axon terminal.

Anterograde Transport

Axonal transport carrying molecular cargo forward from the cell body toward the axon tip or terminal.

Retrograde Transport

Axonal transport carrying substances backward from the axon terminal toward the cell body.

CB1 Receptors

Abundant brain cell membrane receptors that regulate hunger, temperature, and alertness, serve as traffic cops to control other neurotransmitters, and produce the cannabis high.

CB2 Receptors

Cannabinoid receptors found primarily in immune tissues that help regulate immune functioning, modulate intestinal inflammation, contraction, and pain, and do not cause a high.

Anandamide

The first discovered endogenous cannabinoid (arachidonoyl ethanolamide), derived from the Sanskrit word for bliss (ananda), which acts as a retrograde messenger.

2-AG

The second discovered endocannabinoid (2-arachidonoyl glycerol), synthesized naturally in the body to serve as a retrograde messenger.

Central Nervous System (CNS)

The major division of the nervous system consisting of the brain (including the retinas) and the spinal cord.

Peripheral Nervous System (PNS)

All neurons situated outside the central nervous system, consisting of 31 pairs of spinal nerves and 12 pairs of cranial nerves.

Neuron

The basic cellular unit of the nervous system, occurring in motor and sensory types, unipolar, bipolar, or multipolar forms, and consisting of axons, dendrites, and a soma or cell body.

Unipolar Neuron

A structural class of nerve cell characterized by having only a single process extending from the soma that divides into two functional branches.

Bipolar Neuron

A structural class of nerve cell featuring two distinct processes extending from opposite ends of the cell body: one dendrite and one axon.

Multipolar Neuron

The most common structural class of nerve cell, possessing a single axon and multiple dendrites extending from the soma.