Chapter 1: Nerve Cells and Nerve Impulses (Biological Psychology)

Vocabulary flashcards covering key terms and concepts from Chapter 1: Nerve Cells and Nerve Impulses.

Neuron

A nerve cell that receives information and transmits it to other cells; the basic unit of the nervous system.

Glia

Non-neuronal support cells of the nervous system, including astrocytes, microglia, oligodendrocytes, Schwann cells, and radial glia.

Resting potential

The steady electrical charge across a neuron's membrane when it is not firing; inside is negative relative to outside.

Polarization

A state in which there is a difference in charge across the cell membrane; at rest the neuron is polarized.

Sodium–potassium pump

An active transport protein that moves three Na+ out and two K+ in to maintain the resting potential.

Ion concentration gradient

A difference in ion concentrations across the membrane that drives diffusion of ions.

Electrical gradient

A voltage difference across the membrane that drives ion movement.

Action potential

A rapid, stereotyped electrical impulse that travels along an axon when the membrane depolarizes to threshold.

Depolarization

A reduction in the membrane's polarization; the inside becomes less negative.

Hyperpolarization

An increase in polarization; the inside becomes more negative than the resting potential.

Threshold of excitation

The critical level of depolarization required to trigger an action potential.

All-or-none law

Once threshold is reached, the action potential occurs with a standard amplitude and speed; stimulus strength does not change it.

Voltage-gated ion channels

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

Sodium channels

Voltage-gated channels that allow Na+ to enter during an action potential.

Potassium channels

Voltage-gated channels that allow K+ to exit during an action potential.

Nodes of Ranvier

Gaps in the myelin sheath where action potentials are regenerated.

Myelin sheath

Insulating layer around many vertebrate axons that speeds conduction; produced by oligodendrocytes in the CNS and Schwann cells in the PNS.

Saltatory conduction

The jumping of action potentials from node to node in a myelinated axon, speeding conduction.

Propagation of the action potential

The process by which the action potential moves along the axon from one region to the next.

Refractory period

The period after an action potential during which it is difficult or impossible to fire another; includes absolute and relative phases.

Absolute refractory period

The brief period after an AP during which no new AP can be initiated.

Relative refractory period

A period after the absolute phase where a stronger stimulus is needed to trigger an AP.

Local neuron

A neuron without an axon; uses graded potentials to signal nearby neurons.

Dendrite

A branched extension of a neuron that receives information; contains synaptic receptors.

Dendritic spine

Small protrusions on dendrites that increase surface area for synapses.

Soma (cell body)

The metabolic center of the neuron, containing nucleus, ribosomes, and mitochondria.

Axon

Long fiber that transmits impulses away from the soma to other neurons, muscles, or glands.

Presynaptic terminal

The end of an axon where neurotransmitters are released into the synapse.

Axon hillock

The region where the axon originates and where action potentials are typically initiated.

Afferent

Axons or fibers that carry information into a structure (incoming information).

Efferent

Axons or fibers that carry information away from a structure (outgoing information).

Interneuron (intrinsic neuron)

A neuron whose axon and dendrites remain within a single structure, functioning locally.

Astrocyte

A star-shaped glial cell that surrounds synapses, buffers ions, and helps synchronize related neurons; involved in blood flow and possibly tripartite synapse.

Microglia

Glial immune cells in the brain that remove pathogens, damaged neurons, and prune weak synapses.

Oligodendrocyte

CNS glial cells that form myelin sheaths around multiple axons.

Schwann cell

PNS glial cells that form myelin around axons.

Radial glia

Glial cells that guide neuronal migration during embryonic development and often differentiate into neurons or other glia.

Blood–brain barrier

A selective barrier formed by tightly joined endothelial cells that protects the brain from most blood-borne chemicals while allowing essential nutrients to pass.

Endothelial cells

Cells lining the blood vessels that organize the barrier in the brain.

Passive transport

Movement of substances across the barrier without energy; small uncharged molecules and lipid-soluble substances cross easily.

Active transport

Protein-mediated transport that requires energy to move chemicals into the brain.

Glucose transport across BBB

Glucose is actively transported into the brain and serves as its main fuel.

Tripartite synapse

Concept that synapses involve presynaptic neuron, postsynaptic neuron, and astrocyte interactions.

Neurotransmitter

Chemicals released by neurons at synapses that cross the synaptic gap and affect the next neuron.

Golgi stain

A staining method that reveals the detailed structure of individual neurons, supporting the neuron doctrine.

Santiago Ramón y Cajal

Pioneer who showed neurons are discrete cells and helped establish the neuron doctrine.

Neuron doctrine

Concept that the nervous system is composed of discrete cells called neurons.

Nucleus

Membrane-bound organelle containing chromosomes with genetic information.

Mitochondrion

Energy-producing organelle with its own DNA.

Ribosome

Organelle where proteins are synthesized.

Endoplasmic reticulum

Membrane network involved in protein synthesis, folding, and transport.

Synapse

Junction where communication occurs between neurons via neurotransmitters.

Synaptic receptors

Receptors on the postsynaptic membrane that respond to neurotransmitters.