Graded Potentials Lecture Review

Vocabulary flashcards covering key terms related to graded potentials, action potentials, ion channels, and basic nervous system organization.

Gated channels

Membrane proteins that can open and close, regulating the flow of ions across the cell membrane and changing its resistance.

Chemical (ligand) gated channels

Ion channels that open when a specific neurotransmitter or other chemical binds to them.

Mechanical gated channels

Ion channels that open when a physical force deforms the cell membrane.

Voltage gated channels

Ion channels that open when the membrane's electrical potential changes to a critical level (threshold voltage).

Graded (local) potential

A small, localized change in membrane potential that can be depolarizing or hyperpolarizing, and whose strength varies with the strength of the stimulus.

Threshold potential

The critical membrane voltage level that, when reached, triggers the opening of voltage-gated channels and initiates an action potential.

Action potential

Large, regenerative changes in membrane voltage (nerve impulses) that propagate along the membrane without decreasing in strength.

Stimulus (for graded potentials)

A physical force or a chemical binding (e.g., neurotransmitter) that initiates a graded potential by opening gated channels.

Excitatory potentials

Graded potentials that depolarize the membrane, bringing it closer to the threshold for firing an action potential.

Inhibitory potentials

Graded potentials that hyperpolarize the membrane, moving it further from the threshold for firing an action potential.

Depolarization

A decrease in the negativity of the membrane potential (the inside of the cell becomes less negative, moving closer to 0 mV), often due to the influx of positive ions like Na+.

Hyperpolarization

An increase in the negativity of the membrane potential (the inside of the cell becomes more negative), often due to the efflux of K+ or influx of Cl-.

Resistance (membrane)

Anything that hinders the flow of electrical charges (ions) across the cell membrane.

Passive transport

Movement of substances across a cell membrane that does not require cellular energy input, including simple and facilitated diffusion.

Simple diffusion

Movement of lipid-soluble solutes directly through the plasma membrane without the aid of membrane proteins.

Facilitated diffusion

Movement of substances across a cell membrane with the help of membrane proteins (channels or carriers) but still down their concentration gradient.

Channel proteins

Integral membrane proteins that form pores or passageways through the lipid bilayer, allowing specific small water-soluble molecules and ions to diffuse.

Open/Leak channels

Type of channel protein that remains open all the time, allowing continuous ion flow across the membrane.

Carrier proteins

Membrane proteins involved in facilitated diffusion that bind to a specific solute and change conformation to transport it across the membrane, typically only open to one side at a time.

Neural circuits

A network of neurons consisting of afferent, inter-, and efferent neurons that work together for communication and regulation within the nervous system.

Afferent (sensory) neurons

Neurons that transmit signals from sensory receptors to the Central Nervous System (CNS).

Interneurons (association neurons)

Neurons located entirely within the Central Nervous System (CNS) that integrate information and connect afferent and efferent neurons.

Efferent (motor) neurons

Neurons that transmit signals from the Central Nervous System (CNS) to effector organs, such as muscles and glands.

Ligand

A molecule, such as a neurotransmitter, that binds to a specific receptor site on a protein (e.g., a ligand-gated channel) to elicit a response.