Chapter 37: Neurons, Synapses, and Signaling – Key Vocabulary

A comprehensive set of vocabulary flashcards covering the major terms from Chapter 37 on neurons, synapses, and signaling.

neuron

A nerve cell; the fundamental unit of the nervous system that conducts signals by exploiting the electrical charge across its plasma membrane.

cell body

The portion of a neuron that houses the nucleus and most other organelles.

dendrite

A short, highly branched neuron extension that receives signals from other neurons.

axon

A typically long neuron extension that carries nerve impulses away from the cell body toward target cells.

synapse

The junction where a neuron communicates with another cell across a narrow gap via a neurotransmitter or electrical coupling.

neurotransmitters

Molecules released from a neuron's synaptic terminal that diffuse across the synaptic cleft and bind to the postsynaptic cell, triggering a response.

glial cells (glia)

Non-neuronal nervous-system cells that support, regulate, nourish, and insulate neurons and remove pathogens and dead cells.

brain

Organ of the central nervous system where information is processed and integrated.

ganglion

A structure containing a number of nerve cell bodies linked by synapses, often forming a swelling on a nerve fiber.

sensory neuron

A nerve cell that receives information from the internal or external environment and transmits signals to the central nervous system.

interneuron

An association neuron within the CNS that forms synapses with sensory and/or motor neurons and integrates sensory input and motor output.

motor neuron

A nerve cell that transmits signals from the brain or spinal cord to muscles or glands.

central nervous system (CNS)

The portion of the nervous system where signal integration occurs; in vertebrates, the brain and spinal cord.

peripheral nervous system (PNS)

The sensory and motor neurons that connect to the central nervous system.

nerve

A fiber composed primarily of bundled axons of neurons.

membrane potential

The charge difference (voltage) across a cell's plasma membrane.

resting potential

The membrane potential characteristic of a nonconducting excitable cell, with the inside of the cell more negative than the outside.

sodium-potassium pump

A plasma-membrane transport protein that actively transports sodium out of the cell and potassium into the cell.

ion channel

A transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient.

equilibrium potential

The magnitude of a cell’s membrane voltage at equilibrium, calculated using the Nernst equation.

gated ion channel

An ion channel whose opening or closing is controlled, thereby altering a cell’s membrane potential.

voltage-gated ion channel

A specialized ion channel that opens or closes in response to changes in membrane potential.

hyperpolarization

A change in membrane potential that makes the inside of the membrane more negative relative to the outside, reducing the chance of a nerve impulse.

depolarization

A change in membrane potential that makes the inside of the membrane less negative (moves toward zero voltage).

graded potential

A shift in membrane potential with an amplitude proportional to signal strength that decays as it spreads.

action potential

An electrical signal that propagates along a neuron’s membrane as an all-or-none depolarization.

threshold

The membrane potential that an excitable cell must reach to initiate an action potential.

refractory period

The short time after an action potential during which the neuron cannot respond to another stimulus owing to inactivated voltage-gated sodium channels.

myelin sheath

An insulating coat of cell membranes wrapped around an axon by Schwann cells or oligodendrocytes, interrupted by nodes of Ranvier.

oligodendrocytes

Glial cells that form insulating myelin sheaths around axons in the central nervous system.

Schwann cell

Glial cell that forms insulating myelin sheaths around axons in the peripheral nervous system.

nodes of Ranvier

Gaps in the myelin sheath where action potentials are generated, enabling saltatory conduction.

saltatory conduction

Rapid transmission of a nerve impulse along an axon in which the action potential jumps from one node of Ranvier to the next.

excitatory postsynaptic potential (EPSP)

A depolarization of a postsynaptic membrane caused by an excitatory neurotransmitter, making an action potential more likely.

inhibitory postsynaptic potential (IPSP)

A hyperpolarization of a postsynaptic membrane caused by an inhibitory neurotransmitter, making an action potential less likely.

summation

A neural integration phenomenon in which the postsynaptic membrane potential results from combined EPSPs or IPSPs in time or space.

acetylcholine

A common neurotransmitter that binds to receptors and alters postsynaptic membrane permeability, either depolarizing or hyperpolarizing the membrane.

neuropeptides

Relatively short chains of amino acids that serve as neurotransmitters.

endorphin

Hormones produced in the brain and anterior pituitary that inhibit pain perception.