Organic Brain Biopsychology Chapter 2

Front 1

Absolute refractory period

Back 1

the 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.

Front 2

Action potential

Back 2

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

Front 3

Active transport

Back 3

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

Front 4

Afferent axon

Back 4

neuron that brings information INTO the structure.

Front 5

All-or-none law

Back 5

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

Front 6

Amino acids

Back 6

acids containing an amine group.

Front 7

Amnesia

Back 7

memory loss.

Front 8

Astrocyte (astroglia)

Back 8

relatively large, star-shaped glia cell.

Front 9

Axon hillock

Back 9

swlling of the soma, the point where the axon begins.

Front 10

Axons

Back 10

single thin fibers of constant diameter that extend from a neuron.

Front 11

Bipolar cells

Back 11

type of neuron in the retina that receives input directly from the receptors.

Front 12

Blood-brain barrier

Back 12

the mechanism that keeps many chemicals out of the brain.

Front 13

Cell body (soma)

Back 13

the structure of a cell that contains the nucleus.

Front 14

Dendrite

Back 14

branching fiber that emanates from a neuron, growing narrower as it extends from the cell body toward the periphery.

Front 15

Dendritic spine

Back 15

short outgrowth along the dendrites.

Front 16

Depolarization

Back 16

reduction in the level of polarization across a membrane.

Front 17

Efferent axon

Back 17

neuron that carries information AWAY from the structure.

Front 18

Electrical gradient

Back 18

difference in positive and negative charges across the membrane.

Front 19

Endoplasmic reticulum

Back 19

network of thin tubes within a cell that transport synthesized proteins to other locations.

Front 20

General anesthetics

Back 20

drugs that decrease brain activity by opening potassium channels wider than usual.

Front 21

Glia

Back 21

type of cell in the nervous system that do not conduct impulses to other cells (unlike neurons)

Front 22

Glucose

Back 22

a simple sugar; main fuel of vertebrate neurons.

Front 23

Graded potential

Back 23

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

Front 24

Hormones

Back 24

chemicals secreted by glands and conveyed by the blood to other organs, which are influenced by their activity.

Front 25

Hyperpolarization

Back 25

increased polarization across a membrane.

Front 26

Intrinsic neuron

Back 26

a neuron whos axons and dendrites are all confined within a given structure.

Front 27

Korsakoff's syndrome

Back 27

a type of brain damate caused by thiamine deficiency, characterized by apathy, confusion, and memory impairment.

Front 28

Local anesthetic

Back 28

drug that attatches to the sodium channels of the membrane, preventing sodium ions from entering and thereby block action potentials (in this case, pain)

Front 29

Local neuron

Back 29

small neuron with a very short, or no axon.

Front 30

Membrane

Back 30

structure that separates the inside of a cell from the outside.

Front 31

Microglia

Back 31

very small cells.

Front 32

Mictochondrion (pl: mitochondria)

Back 32

the structure where the cell performs the metabolic activities that provide energy.

Front 33

Motor neuron

Back 33

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

Front 34

Myelin sheath

Back 34

insulating material that covers many vertebrate axons.

Front 35

Myelinated axon

Back 35

an axon covered with a myelin sheath

Front 36

Neurons

Back 36

cells that receive information and transmit it to other cells by conduction electrochemical impulses.

(See: Synapses)

Front 37

Node of Ranvier

Back 37

small, unmyelinated gap along the axon between segments of myelin.

Front 38

Nucleus

Back 38

Def. 1: structure within a cell that contains the chromosomes.
Def 2: cluster of neuron cell bodies within the central nervous system.

Front 39

Oligodenrocytes

Back 39

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

Front 40

Polarization

Back 40

the electrical gradient across a membrane.

Front 41

Presynaptic terminal

Back 41

the tip of an axon from where the axon releases chemicals into the synapse.

Front 42

Propogation of the action potential

Back 42

the transmission of an action potential down an axon.

Front 43

Radial glia

Back 43

typoe of glia cells that guide the migration of neurons and the growth of their axons and dendrites during embryological development.

Front 44

Refractory period

Back 44

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

Front 45

Relative refractory period

Back 45

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

Front 46

Resting potential

Back 46

the elctrical potential across a membrane when a neuron is not being stimulated.

Front 47

Ribosome

Back 47

the site where the cell synthesizes new protein molecules.

Front 48

Saltatory conduction

Back 48

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

Front 49

Schwann cell

Back 49

a glia cell that surrounds and insulates acertain axons in the periphery of the vertebrate body.

Front 50

Selective permeability

Back 50

certain chemicals ability to pass more freely than other chemicals through a membrane.

Front 51

Sensory neuron

Back 51

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

Front 52

Sodium-potassium pump

Back 52

the mechanism that actively "pumps" three sodium ions out of the cell while simultaneously "pumps" in two potassium ions.

Front 53

Soma (cell body)

Back 53

the structure of a cell that contains the nucleus.

Front 54

Thiamine
(Vitamin B1)

Back 54

a chemical necessary for the metabolism of glucose.

Front 55

Threshold of excitation

Back 55

the level of depolarization when a brief stimulation triggers a rapid, massive electrical change by the membrane.

Front 56

Voltage-activiated channel

Back 56

a membrane channel whose permeability to sodium (or any other ion) depends on the voltage difference across the membrane.