The Nervous System

Vocabulary practice flashcards covering resting membrane potential, action potential, neuronal synapses, brain regions, meninges, CSF circulation, spinal cord anatomy, and cranial nerves based on lecture notes.

Resting Membrane Potential

The electrical potential difference across a cell membrane when the cell is not actively generating an action potential, characterized by a negative charge inside relative to the outside and a voltage of $-70\text{ mV}$.

PISO

A mnemonic used to remember the direction of active ion transport by the sodium-potassium pump: Potassium In, Sodium Out.

Sodium-Potassium Pump

An active transport protein that maintains resting ion levels across the cell membrane by moving 3 $Na^+$ ions out of the cell and 2 $K^+$ ions into the cell, consuming $70\%$ of a neuron's ATP.

Sodium ($Na^+$)

The major extracellular cation in the body, with a normal resting concentration of $140\text{ mEq/L} \pm 5$.

Potassium ($K^+$)

The major intracellular cation in the body, with a normal resting concentration of $3.5\text{--}5.0\text{ mEq/L}$.

Chlorine ($Cl^-$)

The major extracellular anion in the body, present at a concentration of $100\text{--}110\text{ mEq/L}$.

Leak Channels

Membrane channel proteins that allow passive diffusion of ions; neuronal membranes contain 50 to 100 times more $K^+$ leak channels than $Na^+$ leak channels.

Depolarization

The first phase of an action potential triggered when threshold is reached, causing a massive 600-fold increase in $Na^+$ permeability as $Na^+$ rushes into the cell, making the inside positive relative to the outside.

Repolarization

The phase of an action potential in which $Na^+$ channels close and voltage-gated $K^+$ channels open, allowing $K^+$ to exit the cell and restoring the negative interior charge.

Hyperpolarization

A brief period following repolarization where the membrane potential becomes more negative than the resting state due to continued outflow of $K^+$ or influx of $Cl^-$ or $K^+$ ions.

Continuous Conduction

The slow propagation of an action potential along the entire length of an unmyelinated axon, occurring at speeds of $0.5\text{--}1.0\text{ m/s}$.

Saltatory Conduction

The rapid propagation of an action potential along a myelinated axon, where the electrical signal jumps between unmyelinated gaps called nodes of Ranvier.

Spatial Summation

The integration of postsynaptic potentials originating from different physical locations across a neuron's membrane at the same time.

Temporal Summation

The integration of multiple postsynaptic potentials occurring in rapid succession over time at a single location on a neuron.

Cerebral Lobes

The four main functional divisions of the cerebrum: Frontal (motor and executive), Parietal (somatic sensation), Temporal (hearing and memory), and Occipital (vision).

Basal Ganglia

Deep gray matter nuclei within the cerebrum that influence voluntary motor control and are associated with Parkinson's disease.

Central Sulcus

The anatomical groove on the surface of the cerebrum that separates the frontal lobe from the parietal lobe.

Lateral Sulcus

The deep groove on the cerebral cortex that separates the frontal and parietal lobes above from the temporal lobe below.

Diencephalon

The central core region of the brain consisting primarily of the thalamus (sensory relay) and hypothalamus (homeostasis and temperature regulation).

Midbrain

The most superior section of the brainstem, which gives rise to cranial nerves III (Oculomotor) and IV (Trochlear).

Pons

The middle section of the brainstem that serves as the origin for cranial nerves V (Trigeminal), VI (Abducens), VII (Facial), and VIII (Vestibulocochlear).

Medulla Oblongata

The most inferior part of the brainstem containing vital reflex pathways and giving rise to cranial nerves IX, X, XI, and XII.

Cerebellum

The region located posterior to the brainstem, known as the 'small brain', which coordinates voluntary movement, maintains balance, and supports posture.

Ischemia

A reduction in blood supply to brain tissue causing oxygen deprivation; prolonged ischemia leads to neuronal cell death within $5\text{--}6\text{ minutes}$.

Epidural Space

The meningeal space located between the skull or vertebral column and the outer dura mater layer.

Subarachnoid Space

The fluid-filled meningeal space situated between the arachnoid mater and pia mater through which cerebrospinal fluid (CSF) circulates.

Choroid Plexus

A specialized network of capillaries located within the brain ventricles that produces cerebrospinal fluid (CSF).

Hydrocephalus

A pathological condition caused by an obstruction in CSF flow or drainage, resulting in an abnormal accumulation or pooling of cerebrospinal fluid in the brain.

Spinal Cord Gray Matter

The central butterfly-shaped core of the spinal cord that contains neuronal cell bodies and is organized into dorsal, lateral, and ventral horns.

Dorsal Roots

Posterior nerve root structures attached to the spinal cord that transmit incoming sensory signals; damage to these structures impairs sensation.

Ventral Roots

Anterior nerve root structures attached to the spinal cord that carry outgoing motor impulses; damage to these structures causes motor weakness or paralysis.

Olfactory Nerve (CN I)

Cranial Nerve I; a purely sensory cranial nerve dedicated to the sense of smell.

Optic Nerve (CN II)

Cranial Nerve II; a purely sensory cranial nerve dedicated to vision.

Trigeminal Nerve (CN V)

Cranial Nerve V; a mixed cranial nerve responsible for facial sensation and mastication (chewing).

Vestibulocochlear Nerve (CN VIII)

Cranial Nerve VIII; a purely sensory cranial nerve responsible for hearing and balance.

Vagus Nerve (CN X)

Cranial Nerve X; a mixed cranial nerve providing visceral parasympathetic innervation to internal organs.