Ch 2: Structure and Functions of Cells of the Nervous System.

Question 1

Sensory Neuron

Answer 1

A neuron that detects changes in the external or internal environment and sends information about these changes to the central nervous system.

Question 2

Motor Neuron

Answer 2

A neuron located within the central nervous system that controls the contraction of a muscle or the secretion of a gland.

Question 3

Interneuron

Answer 3

A neuron located entirely within the central nervous system.

Question 4

Central Nervous System (CNS)

Answer 4

The brain and spinal cord.

Question 5

Peripheral Nervous System (PNS)

Answer 5

The part of the nervous system outside the brain and spinal cord, including the nerves attached to the brain and spinal cord.

Question 6

Soma

Answer 6

The cell body of a neuron, which contains the nucleus.

Question 7

Dendrite

Answer 7

A branched, treelike structure attached to the soma of a neuron; receives information from the terminal buttons of other neurons.

Question 8

Synapse

Answer 8

A junction between the terminal button of an axon and the membrane of another neuron.

Question 9

Axon

Answer 9

The long, thin, cylindrical structure that conveys information from the soma of a neuron to its terminal buttons.

Question 10

Multipolar Neuron

Answer 10

A neuron with one axon and many dendrites attached to its soma.

Question 11

Unipolar Neuron

Answer 11

A neuron with one axon attached to its soma; the axon divides, with one branch receiving sensory information and the other sending the information into the central nervous system.

Question 12

Terminal Button

Answer 12

The bud at the end of a branch of an axon; forms synapses with another neuron; sends information to the neuron.

Question 13

Neurotransmitter

Answer 13

A chemical that is released by a terminal button; has an excitatory or inhibitory effect on another neuron.

Question 14

Membrane

Answer 14

A structure consisting principally of lipid molecules that defines the outer boundaries of a cell and also constitutes many of the cell organelles, such as the Golgi apparatus.

Question 15

Nucleus

Answer 15

A structure in the central region of a cell, containing the nucleolus and chromosomes.

Question 16

Nucleolus (new clee o lus)

Answer 16

A structure within the nucleus of a cell that produces the ribosomes.

Question 17

Ribosome

Answer 17

A cytoplasmic structure, made of protein, that serves as the site of production of proteins translated from mRNA.

Question 18

Chromosome

Answer 18

A strand of DNA, with associated proteins, found in the nucleus; carries genetic information.

Question 19

Deoxyribonucleic Acid (DNA)

Answer 19

A long, complex macromolecule consisting of two interconnected helical strands; along with associated proteins, strands of DNA constitute the chromosomes.

Question 20

Gene

Answer 20

The functional unit of the chromosome, which directs synthesis of one or more proteins.

Question 21

Messenger Ribonucleic Acid (mRNA)

Answer 21

A macromolecule that delivers genetic information concerning the synthesis of a protein from a portion of a chromosome to a ribosome.

Question 22

Enzyme

Answer 22

A molecule that controls a chemical reaction, combining two substances or breaking a substance into two parts.

Question 23

Non-coding RNA (ncRNA)

Answer 23

A form of RNA that does not encode for protein but has functions of its own.

Question 24

Cytoplasm

Answer 24

The viscous, semiliquid substance contained in the interior of a cell.

Question 25

Mitochondrion

Answer 25

An organelle that is responsible for extracting energy from nutrients.

Question 26

Adenosine Triphosphate (ATP) [ah den o seen]

Answer 26

A molecule of prime importance to cellular energy metabolism; its breakdown liberates energy.

Question 27

Endoplasmic Reticulum

Answer 27

Parallel layers of membrane found within the cytoplasm of a cell. Rough endoplasmic reticulum contains ribosomes and is involved with production of proteins that are secreted by the cell. Smooth endoplasmic reticulum is the site of synthesis of lipids and provides channels for the segregation of molecules involved in various cellular processes.

Question 28

Golgi Apparatus

Answer 28

A complex of parallel membranes in the cytoplasm that wraps the products of a secretory cell.

Question 29

Exocytosis

Answer 29

The secretion of a substance by a cell through means of vesicles; the process by which neurotransmitters are secreted.

Question 30

Lysosome

Answer 30

An organelle surrounded by membrane; contains enzymes that break down waste products.

Question 31

Cytoskeleton

Answer 31

Formed of microtubules and other protein fibers, linked to each other and forming a cohesive mass that gives a cell its shape.

Question 32

Microtubule

Answer 32

A long strand of bundles of protein filaments arranged around a hollow core; part of the cytoskeleton and involved in transporting substances from place to place within the cell.

Question 33

Axoplasmic Transport

Answer 33

An active process by which substances are propelled along microtubules that run the length of the axon.

Question 34

Anterograde

Answer 34

In a direction along an axon from the cell body toward the terminal buttons.

Question 35

Retrograde

Answer 35

In a direction along an axon from the terminal buttons toward the cell body.

Question 36

Glia (glee ah)

Answer 36

The supporting cells of the CNS

Question 37

Astrocyte

Answer 37

A glial cell that provides support for neurons of the central nervous system, provides nutrients and other substances, and regulates the chemical composition of the extracellular fluid.

Question 38

Phagocytosis (fagg o sy toe sis)

Answer 38

The process by which cells engulf and digest other cells or debris caused by cellular degeneration.

Question 39

Oligodendrocyte

Answer 39

A type of glial cell in the central nervous system that forms myelin sheaths.

Question 40

Myelin Sheath

Answer 40

A sheath that surrounds axons and insulates them, preventing messages from spreading between adjacent axons.

Question 41

Node of Ranvier

Answer 41

A naked portion of myelinated axon between adjacent oligodendroglia or Schwann cells.

Question 42

Microglia

Answer 42

The smallest of glial cells; act as phagocytes and protect the brain from invading microorganisms.

Question 43

Schwann Cell

Answer 43

A cell in the peripheral nervous system that is wrapped around a myelinated axon, providing one segment of its myelin sheath.

Question 44

Blood-brain Barrier

Answer 44

A semipermeable barrier between the blood and the brain produced by the cells in the walls of the brain's capillaries.

Question 45

Area Postrema

Answer 45

A region of the medulla where the blood-brain barrier is weak; poisons can be detected there and can initiate vomiting.

Question 46

Electrode

Answer 46

A conductive medium that can be used to apply electrical stimulation or to record electrical potentials.

Question 47

Microelectrode

Answer 47

A very fine electrode, generally used to record activity of individual neurons.

Question 48

Membrane Potential

Answer 48

The electrical charge across a cell membrane; the difference in electrical potential inside and outside the cell.

Question 49

Oscilloscope

Answer 49

A laboratory instrument that is capable of displaying a graph of voltage as a function of time on the face of a cathode ray tube.

Question 50

Resting Potential

Answer 50

The membrane potential of a neuron when it is not being altered by excitatory or inhibitory postsynaptic potentials; approximately -70mV in the giant squid axon.

Question 51

Depolarization

Answer 51

Reduction (toward zero) of the membrane potential of a cell from its normal resting potential.

Question 52

Hyperpolarization

Answer 52

An increase in the membrane potential of a cell, relative to the normal resting potential.

Question 53

Action Potential

Answer 53

The brief electrical impulse that provides the basis for conduction of information along an axon.

Question 54

Threshold of Excitation

Answer 54

The value of the membrane potential that must be reached to produce an action potential.

Question 55

Diffusion

Answer 55

Movement of molecules from regions of high concentration to regions of low concentration.

Question 56

Electrolyte

Answer 56

An aqueous solution of a material that ionizes - namely, a soluble acid, base, or salt.

Question 57

Ion

Answer 57

A charged molecule. Cations are positively charged, and anions are negatively charged.

Question 58

Electrostatic Pressure

Answer 58

The attractive force between atomic particles charged with opposite signs of the repulsive force between atomic particles charged with the same sign.

Question 59

Intracellular Fluid

Answer 59

The fluid contained within cells.

Question 60

Extracellular Fluid

Answer 60

Body fluids located outside of the cell.

Question 61

Sodium-potassium Transporter

Answer 61

A protein found in the membrane of all cells that extrude sodium ions from and transports potassium ions into the cell.

Question 62

Ion Channel

Answer 62

A specialized protein molecule that permits specific ions to enter or leave cells.

Question 63

Voltage-dependent Ion Channel

Answer 63

An ion channel that opens or closes according to the value of the membrane potential.

Question 64

All-or-none Law

Answer 64

The principle that once an action potential is triggered in an axon, it is propagated, without decrement, to the end of the fiber.

Question 65

Rate Law

Answer 65

The principle that variations in the intensity of a stimulus or other information being transmitted in an axon are represented by variations in the rate at which that axon fires.

Question 66

Saltatory Conduction

Answer 66

Conduction of action potentials by myelinated axons. The action potential appears to jump from one node of Ranvier to the next.

Question 67

Postsynaptic Potential

Answer 67

Alterations in the membrane potential of a postsynaptic neuron, produced by liberation of neurotransmitters at the synapse.

Question 68

Binding Site

Answer 68

The location on a receptor protein which a ligand binds.

Question 69

Ligand

Answer 69

A chemical that binds with the binding site of a receptor.

Question 70

Dendritic Spine

Answer 70

A small bud on the surface of a dendrite, with which a terminal button of another neuron forms a synapse.

Question 71

Presynaptic Membrane

Answer 71

The membrane of a terminal button that lies adjacent to the postsynaptic membrane and through which the neurotransmitter is released.

Question 72

Postsynaptic Membrane

Answer 72

The cell membrane opposite the terminal button in a synapse; the membrane of a cell that receives the message.

Question 73

Synaptic Cleft

Answer 73

The space between the presynaptic membrane and the postsynaptic membrane.

Question 74

Synaptic Vesicle

Answer 74

A small, hollow, beadlike structure found in terminal buttons; contains molecules of a neurotransmitter.

Question 75

Release Zone

Answer 75

A region of the interior of the presynaptic membrane of a synapse to which synaptic vesicles attach and release their neurotransmitter into the synaptic cleft.

Question 76

Postsynaptic Receptor

Answer 76

A receptor molecule in the postsynaptic membrane of a synapse that contains a binding site for a neurotransmitter.

Question 77

Neurotransmitter-dependent Ion Channel

Answer 77

An ion channel that opens when a molecule of a neurotransmitter binds with a postsynaptic receptor.

Question 78

Ionotropic Receptor

Answer 78

A receptor that contains a binding site for a neurotransmitter and an ion channel that opens when a molecule of the neurotransmitter attaches to the binding site.

Question 79

Metabotropic Receptor

Answer 79

A receptor that contains a binding site for a neurotransmitter; activates an enzyme that begins a series of events that opens an ion channel elsewhere in the membrane of the cell when a molecule of the neurotransmitter attaches to the binding site.

Question 80

G Protein

Answer 80

A protein coupled to a metabotropic receptor; conveys messages to other molecules when a ligand binds with and activates the receptor.

Question 81

Second Messenger

Answer 81

A chemical produced when a G protein activates an enzyme; carries a signal that results in the opening of the ion channel of causes other events to occur in the cell.

Question 82

Excitatory Postsynaptic Potential (EPSP)

Answer 82

An excitatory depolarization of the postsynaptic membrane of a synapse caused by the liberation of a neurotransmitter by the terminal button.

Question 83

Inhibitory Postsynaptic Potential (IPSP)

Answer 83

An inhibitory hyperpolarization of the postsynaptic membrane of a synapse caused by the liberation of a neurotransmitter by the terminal button.

Question 84

Reuptake

Answer 84

The reentry of a neurotransmitter just liberated by a terminal button back through its membrane, thus terminating the postsynaptic potential.

Question 85

Enzymatic Deactivation

Answer 85

The destruction of a neurotransmitter by an enzyme after its release - for example, the destruction of acetylcholine by acetylcholinesterase.

Question 86

Acetylcholine (ACh)

Answer 86

A neurotransmitter found in the brain, spinal cord, and parts of the PNS; responsible for muscular contraction.

Question 87

Acetylcholinesterase (AChE)

Answer 87

The enzyme that destroys acetylcholine soon after it is liberated by the terminal buttons, thus terminating the postsynaptic potential.

Question 88

Neural Integration

Answer 88

The process by which inhibitory and excitatory postsynaptic potentials summate and control the rate of firing of a neuron.

Question 89

Autoreceptor

Answer 89

A receptor molecule located on a neuron that responds to the neurotransmitter released by that neuron.

Question 90

Presynaptic Inhibition

Answer 90

The action of a presynaptic terminal button in an axoaxonic synapse; reduces the amount of neurotransmitters released by the postsynaptic terminal buttons.

Question 91

Presynaptic Facilitation

Answer 91

The action of a presynaptic terminal button in an axoaxonic synapse; increases the amount of neurotransmitters released by the postsynaptic terminal button.

Question 92

Gap Junction

Answer 92

A special junction between cells that permits direct communication by means of electrical coupling.

Question 93

Neuromodulator

Answer 93

A naturally secreted substance that acts like a neurotransmitter except that it is not restricted to the synaptic cleft but diffuses through the extracellular fluid.

Question 94

Peptide

Answer 94

A chain of amino acids joined together by peptide bonds. Most neuromodulators, and some hormones, consist of peptide bonds.

Question 95

Hormone

Answer 95

A chemical substance that is released by an endocrine gland that has effects on target cells in other organs.

Question 96

Endocrine Gland

Answer 96

A gland that liberates its secretions into the extracellular fluid around capillaries and hence into the bloodstream.

Question 97

Target Cell

Answer 97

The type of that is directly affected by a hormone or other chemical signal.

Question 98

Steroid

Answer 98

A chemical of low molecular weight, derived from cholesterol. Steroid hormones affect their target cells by attaching to receptors found within the nucleus.