Physiological Psychology: Chapter 2

Question 1

Absolute Refractory Period

Answer 1

time immediately after an action potential, when the sodium gates close and the membrane cannot produce an action potential in response to stimulation of any intensity

Question 2

Action Potential

Answer 2

rapid depolarization and slight reversal of the usual polarization caused by stimulation beyond the threshold

Question 3

Active Transport

Answer 3

protein-mediated process that expends energy to pump chemicals from the blood into the brain

Question 4

Afferent Axon

Answer 4

neuron that brings information into a structure

Question 5

All-or-None Law

Answer 5

principle stating that the size, amplitude, and velocity of the action potential are independent of the intensity of the stimulus that initiated it

Question 6

Astrocyte

Answer 6

relatively large, star-shaped glia cell

Question 7

Axon

Answer 7

single thin fiber of constant diameter that extends from a neuron

Question 8

Axon Hillock

Answer 8

swelling of the soma, the point where the axon begins

Question 9

Blood-Brain Barrier

Answer 9

mechanism that keeps many chemicals out of the brain

Question 10

Cell Body

Answer 10

soma; structure of a cell that contains the nucleus

Question 11

Concentration Gradient

Answer 11

difference in distribution of ions across a membrane

Question 12

Dendritic Spine

Answer 12

short outgrowth along the dendrites

Question 13

Depolarization

Answer 13

reduction in the level of polarization across a membrane

Question 14

Efferent Axon

Answer 14

neuron that carries information away from a structure

Question 15

Electrical Gradient

Answer 15

difference in positive and negative charges across a membrane

Question 16

Endoplasmic Reticulum

Answer 16

network of thin tubes within a cell that transports newly synthesized proteins to other locations

Question 17

Glia

Answer 17

type of cell in the nervous system that, in contrast to neurons, does not conduct impulses to other cells

Question 18

Glucose

Answer 18

a simple sugar, the main fuel of vertebrate neurons

Question 19

Graded Potential

Answer 19

membrane potential that varies in magnitude and does not follow the all-or-none law

Question 20

Hyperpolarization

Answer 20

increased polarization across a membrane

Question 21

Interneuron

Answer 21

neuron whose axons and dendrites are entirely contained within a given structure

Question 22

Intrinsic Neuron

Answer 22

neuron whose axons and dendrites are all confined within a given structure

Question 23

Local Anesthetic

Answer 23

drug that attaches to the sodium channels of the membrane, preventing sodium ions from entering and thereby blocking action potentials

Question 24

Local Neuron

Answer 24

small neuron with no axon or a very short one

Question 25

Membrane

Answer 25

structure that separates the inside of a cell from the outside

Question 26

Microglia

Answer 26

very small neurons that remove waste materials and microorganisms from the central nervous system

Question 27

Mitochondrion

Answer 27

structure where the cell performs the metabolic activities that provide energy

Question 28

Motor Neuron

Answer 28

neuron that receives excitation from other neurons and conducts impulses from its soma in the spinal cord to muscle or gland cells

Question 29

Myelin

Answer 29

insulating material composed of fats and proteins

Question 30

Myelin Sheath

Answer 30

insulating material that covers many vertebrate axons

Question 31

Myelinated Axon

Answer 31

axon covered with a myelin sheath

Question 32

Neuron

Answer 32

cell that receives information and transmits it to other cells by conducting electrochemical impulses

Question 33

Node of Ranvier

Answer 33

short unmyelinated section of axon between segments of myelin

Question 34

Nucleus

Answer 34

structure within a cell that contains the chromosomes; also a cluster of neuron cell bodies within the CNS

Question 35

Oligodendrocytes

Answer 35

glia cells that surround and insulate certain axons in the vertebrate brain and spinal cord

Question 36

Polarization

Answer 36

electrical gradient across a membrane

Question 37

Presynaptic Terminal

Answer 37

tip of an axon, the point from which the axon releases chemicals

Question 38

Propagation of the Action Potential

Answer 38

transmission of an action potential down an axon

Question 39

Radial Glia

Answer 39

type of glia cells that guides the migration of neurons and the growth of their axons and dendrites during embryological development

Question 40

Refractory Period

Answer 40

brief period following an action potential, when the cell resists the production of further action potentials

Question 41

Relative Refractory Period

Answer 41

time after the absolute refractory period, when potassium gates remain open wider than usual, requiring a stronger than usual stimulus to initiate an action potential

Question 42

Resting Potential

Answer 42

electrical potential across a membrane when a neuron is not being stimulated

Question 43

Ribosome

Answer 43

site at which the cell synthesizes new protein molecules

Question 44

Saltatory Conduction

Answer 44

jumping of action potentials from one node to another by the flow of positive ions

Question 45

Schwann Cell

Answer 45

glia cell that surrounds and insulates certain axons in the periphery of the vertebrate body

Question 46

Selective Permeability

Answer 46

ability of certain chemicals to pass more freely than others through a membrane

Question 47

Sensory Neuron

Answer 47

neuron specialized to be highly sensitive to a specific type of stimulation

Question 48

Sodium-Potassium Pump

Answer 48

mechanism that actively transports three sodium ions out of the cell while simultaneously drawing in two potassium ions

Question 49

Thiamine (Vitamin B1)

Answer 49

chemical necessary for the metabolism of glucose

Question 50

Threshold of Excitation

Answer 50

level of depolarization at which a brief stimulation triggers a rapid, massive electrical change by the membrane

Question 51

Voltage-Gated Channel

Answer 51

membrane channel whose permeability to sodium (or some other ion) depends on the voltage diff erence across the membrane