Chapter 1: Nerve Cells and Nerve Impulses - flashcards

A comprehensive set of vocabulary flashcards covering the structures and functions of neurons and glia, the blood-brain barrier, and the mechanics of nerve impulses based on Chapter 1 of Kalat's Biological Psychology.

Neurons

Cells that receive information and transmit it to other cells.

Glia

Cells of the nervous system that serve many functions but do not transmit information like neurons.

Santiago Ramón y Cajal

A pioneer of neuroscience who used staining techniques to show that a small gap separates neurons, proving that the brain consists of individual cells.

Membrane (Plasma membrane)

A structure that separates the inside of the cell from the outside environment and controls the flow of chemicals.

Nucleus

The structure in animal cells that contains the chromosomes.

Mitochondrion

A structure that performs metabolic activities, providing the energy that the cell uses for all activities.

Ribosomes

The sites within a cell that synthesize new protein molecules.

Endoplasmic reticulum

A network of thin tubes that transport newly synthesized proteins to other locations.

Dendrites

Branching fibers that narrow near their ends and receive information from other neurons via specialized synaptic receptors.

Dendritic spines

Short outgrowths on dendrites that increase the surface area available for synapses.

Soma (Cell body)

The part of the neuron that contains the nucleus, ribosomes, and mitochondria, where most metabolic work occurs.

Axon

A thin fiber of constant diameter that conveys an impulse toward other neurons, an organ, or a muscle.

Myelin sheath

An insulating material composed of fats and proteins that covers many vertebrate axons.

Nodes of Ranvier

Interruptions in the myelin sheath along an axon.

Presynaptic terminal

The swelling at the end of an axon branch where chemicals are released to cross the junction to another cell.

Afferent axon

An axon that brings information into a structure.

Efferent axon

An axon that carries information away from a structure.

Intrinsic neuron (Interneuron)

A neuron whose dendrites and axon are entirely contained within a single structure.

Astrocytes

Star-shaped glia that wrap around synapses, shield them from circulating chemicals, and help synchronize the activity of functionally related axons.

Microglia

Cells that act as part of the immune system, removing viruses, fungi, dead neurons, and weak synapses from the brain.

Oligodendrocytes

Glia cells in the brain and spinal cord that build the myelin sheaths for certain vertebrate axons.

Schwann cells

Glia cells in the periphery of the body that build myelin sheaths for vertebrate axons.

Radial glia

Glia that guide the migration of neurons and their axons and dendrites during embryonic development.

Blood-brain barrier

The mechanism that excludes most chemicals from the vertebrate brain to minimize the risk of irreparable brain damage.

Active transport

A protein-mediated process that expends energy to pump chemicals like glucose and amino acids from the blood into the brain.

Glucose

A sugar that serves as the primary nutrient for vertebrate neurons; it is the only nutrient that crosses the blood-brain barrier in large quantities.

Thiamine

Vitamin $B_1$, which is necessary for the body to use glucose.

Resting potential

The difference in voltage (typically $-70\,mV$) between the inside and outside of a neuron's membrane when at rest.

Electrical gradient (Polarization)

A difference in electrical charge between the inside and outside of a cell.

Selective permeability

A property of the cell membrane that allows some chemicals to pass through more freely than others.

Sodium-potassium pump

A protein complex that repeatedly transports three sodium ions out of the cell while drawing two potassium ions into it.

Concentration gradient

The difference in the distribution of ions across the membrane.

Action potential

A rapid depolarization and reversal of the usual electrical charge of a neuron's membrane.

Hyperpolarization

An increase in the negative charge inside a neuron beyond its resting level.

Depolarization

A reduction in the polarization of a neuron toward zero negative charge.

Threshold of excitation

The specific level of depolarization required to produce an action potential.

Voltage-gated channels

Membrane channels whose permeability to certain ions depends on the voltage difference across the membrane.

All-or-none law

The principle that the amplitude and velocity of an action potential are independent of the intensity of the stimulus that initiated it.

Propagation of the action potential

The process by which an action potential is regenerated at each point along an axon without losing strength.

Saltatory conduction

The jumping of action potentials from one node of Ranvier to the next in myelinated axons.

Absolute refractory period

A period during which the membrane cannot produce another action potential, regardless of the strength of the stimulation.

Relative refractory period

A period following the absolute refractory period when a stronger-than-usual stimulus is required to initiate an action potential.

Local neurons

Small neurons without axons that exchange information only with their closest neighbors.

Graded potential

A membrane potential in local neurons that varies in magnitude in proportion to the intensity of the stimulus and decays as it travels.