Chapter 7: Neurons (Vocabulary)

Question 1

Nerve cells involved in intercellular communication. A neuron consists of a cell body, dendrites, and an axon. Neurons are excitable cells in the nervous system specialized to generate and transmit electrochemical signals called action potentials or nerve impulses.

Answer 1

Neurons

Question 2

Cells of the nervous system that support, insulate, and protect nerve cells; also called glial cells.

Answer 2

Neuroglial cell

Question 3

A nerve cell specialized to conduct nerve impulses from the sensory receptors toward the central nervous system.

Answer 3

Sensory (afferent) neuron

Question 4

A neuron specialized to carry information away from the central nervous system to an effector, either a muscle or a gland.

Answer 4

Motor (efferent) neuron

Question 5

A muscle or a gland that brings about a response to a stimulus.

Answer 5

Effector

Question 6

An association neuron. Neurons located within the central nervous system between sensory and motor neurons that serve to integrate information.

Answer 6

Interneuron

Question 7

A process of a neuron specialized to pick up messages and transmit them toward the cell body. There are typically many short branching dendrites on a neuron.

Answer 7

Dendrite

Question 8

A long extension from the cell body of a neuron that carries an electrochemical message away from the cell body toward another neuron or effector (muscle or gland). The tips release a chemical called a neurotransmitter that can affect the activity of the receiving cell. Typically, there is one long one on a neuron.

Answer 8

Axon

Question 9

A bundle of parallel axons, dendrites, or both from many neurons. A nerve is usually covered with tough connective tissue.

Answer 9

Nerve

Question 10

An insulating layer around axons that carry nerve impulses over relatively long distances that is composed of multiple wrappings of the plasma membrane of certain glial cells. Outside the brain and spinal cord, Schwann cells form the _______. It greatly increases the speed at which impulses travel and assists in the repair of damaged axons. The Schwann cells that form the __________ are separated from one another by short regions of exposed axon called notes of Ranvier.

Answer 10

Myelin sheath

Question 11

A type of glial cell in the peripheral nervous system that forms the myelin sheath by wrapping around the axon many times. The myelin sheath insulates axons, increases the speed at which impulses are conducted, and assists in the repair of damaged neurons.

Answer 11

Schwann cell

Question 12

The type of nerve transmission along a delineated axon in which the nerve impulse gums from one node of Ranvier to the next. It greatly increases the speed of nerve conduction.

Answer 12

Saltatory conduction

Question 13

A protein-lined pore or channel through a plasma membrane through which one type or a few types of ions can pass. Nerve cell ion channels are important in the generation and propagation of nerve impulses.

Answer 13

Ion channel

Question 14

A molecular mechanism in a plasma membrane that uses cellular energy in the form of adenosine triphosphate (ATP) to pump ions against their concentration gradients.

Answer 14

Sodium-potassium pump

Typically, each pump ejects three sodium ions from the cell while bringing in two potassium ions.

Question 15

The separation of charge across the plasma membrane of a neuron when the neuron is not transmitting an action potential. It is primarily caused by the unequal distributions of sodium ions, potassium ions, and large negatively charged proteins on either side of the plasma membrane.

Answer 15

Resting potential

The resting potential of a neuron is about -70 mV.

Question 16

A nerve impulse. An electrochemical signal conducted along an axon. A wave of depolarization caused by the inward flow of sodium ions followed by depolarization caused by the outward flow of potassium ions.

Answer 16

Action potential

Question 17

The degree to which the voltage difference across the plasma membrane of a neuron or other excitable cell must change to trigger an action potential.

Answer 17

Threshold

Question 18

The interval following an action potential during which a neuron cannot be stimulated to generate another action potential.

Answer 18

Refractory period

Question 19

A chemical released from the axon tip of a neuron that affects the activity of another cell (usually a nerve, muscle, or gland cell) by altering the electrical potential difference across the membrane of the receiving cell.

Answer 19

Neurotransmitter

Question 20

The junction between a neuron and another cell.

Answer 20

Synapse

Question 21

A phenomenon that results when a muscle is stimulated to contract before it has time to completely relax from a previous contraction. The response to each stimulation builds on the previous one.

Answer 21

Summation (of muscle contraction)

Question 22

A neurotransmitter found in both the central nervous system and the peripheral nervous system. It is the neurotransmitter released at neuromuscular junctions that causes muscle contraction.

Answer 22

Acetylcholine