BIPN 100 Active Recall Document Definitions

A collection of vocabulary flashcards based on lecture notes from BIPN 100 that cover key concepts related to neurosciences and muscle physiology.

Action Potential

A rapid, all-or-none electrical signal that travels along the membrane of a neuron.

Resting Membrane Potential

The electrical potential difference across the neuronal membrane at rest, typically -60 to -70 mV.

Nernst Equation

Used to calculate the equilibrium potential for a single ion based on its concentration gradient.

Graded Potential

A variable-strength signal that decays with distance; used to initiate action potentials.

Absolute Refractory Period

A period after the initiation of an action potential during which another cannot be triggered.

Synaptic Transmission

The process by which a neuron communicates with another cell via neurotransmitter release.

Neurotransmitter

A chemical substance released by neurons to transmit signals across synapses.

Isometric Contraction

Muscle contraction that increases tension without changing muscle length.

Isotonic Contraction

Contraction that shortens the muscle to move a load, maintaining constant tension.

CNS

Central Nervous System; includes the brain and spinal cord.

PNS

Peripheral Nervous System; includes all neural tissue outside the CNS.

Sensory Neuron

Carries information from the sensory receptors to the CNS.

Motor Neuron

Carries commands from the CNS to muscles and glands.

Blood Brain Barrier

A filtering mechanism that blocks certain substances from entering the brain.

Ionotropic Receptor

A ligand-gated ion channel that allows ions to flow in response to a neurotransmitter.

Metabotropic Receptor

A G-protein coupled receptor that initiates intracellular signaling cascades.

Equilibrium Potential (Eion)

The membrane voltage where the net flow of a specific ion is zero.

Ohm’s Law

I = G(Vm - Eion), where current depends on driving force and conductance.

EPSP

Excitatory postsynaptic potential – depolarizes membrane, increasing AP likelihood.

IPSP

Inhibitory postsynaptic potential – hyperpolarizes membrane, decreasing AP likelihood.

Temporal Summation

Multiple rapid signals from one presynaptic neuron combine at the axon hillock.

Spatial Summation

Signals from multiple presynaptic neurons combine at the postsynaptic neuron.

Full Fusion vs. Kiss-and-Run

Two mechanisms of vesicle exocytosis – full fusion releases all contents, kiss-and-run is partial.

Slow-twitch Muscle Fibers

Red fibers, fatigue resistant, use oxidative phosphorylation for ATP.

Fast-twitch Glycolytic Fibers

White fibers, high force, fast fatigue, use anaerobic glycolysis.

Voltage-Gated Channels

Ion channels that open or close in response to changes in membrane potential.

Na+/K+ ATPase

A membrane pump that actively transports 3 Na+ out and 2 K+ into the cell using ATP.

Receptor Potential

A graded potential generated by sensory receptors in response to stimuli.

Cerebral Cortex

The outer layer of the cerebrum involved in higher brain functions such as thought and action.

Spinothalamic Tract

A sensory pathway that transmits pain and temperature information to the brain.

Corticospinal Tract

A motor pathway that transmits movement commands from the brain to the spinal cord.

Tetanus (in muscle)

A sustained muscular contraction resulting from high-frequency stimulation.

End Plate Potential (EPP)

The depolarization of skeletal muscle fibers caused by neurotransmitters binding to receptors at the neuromuscular junction.

Myelin

A fatty substance that insulates axons, speeding up action potential conduction.

Nodes of Ranvier

Gaps in the myelin sheath where voltage-gated Na+ channels are concentrated.

Function of the Blood Brain Barrier

Prevents harmful substances in the bloodstream from entering the brain.

Depolarization

The process of making the inside of a neuron less negative compared to the outside.

Hyperpolarization

An increase in membrane potential making the inside more negative than the resting potential.

Relative Refractory Period

A stronger-than-normal stimulus is required to elicit an action potential.

Absolute Refractory Period

No stimulus, regardless of strength, can trigger an action potential.

Summation at Axon Hillock

Integration of multiple PSPs to determine if threshold is reached for AP.

Role of Ca2+ in NMJ

Triggers vesicle fusion and neurotransmitter release upon entering the presynaptic terminal.

Type I Muscle Fibers

Slow-twitch, fatigue-resistant, rich in mitochondria and myoglobin.

Type IIX Muscle Fibers

Fast-twitch, glycolytic, quickly fatigued, large diameter.

Function of Astrocytes

Support neurons, maintain blood brain barrier, regulate extracellular ion balance.