Pp Chapter One Vocabulary

Front 1

Neurons

Back 1

Cells that receive information and transmit it to other cells.

Front 2

Membrane

Back 2

Structure that separates the inside of the cell from the outside environment.

Front 3

Nucleus

Back 3

The structure that contains the chromosomes.

Front 4

Mitochondria

Back 4

The structure that performs metabolic activities, providing the energy that the cell uses for all activities. Require fuel and oxygen.

Front 5

Ribosomes

Back 5

The sites at which the cell synthesizes new protein molecules. Proteins provide building materials for the cell and facilitate chemical reactions.

Front 6

Endoplasmic Reticulum

Back 6

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

Front 7

Motor neuron.

Back 7

Receives excitation through its dendrites and conducts impulses along its axon to a muscle. The neuron's soma is in the spinal cord.

Front 8

Sensory neuron

Back 8

Specialized at one end to be highly sensitive to a particular type of stimulation, such as light, sound, or touch. Tiny branches lead directly from the receptors into the axon, and the cell's soma is located on a little stalk off the main trunk.

Front 9

Dendrites

Back 9

Branching fibers that get narrower near their ends. Their surface is lined with specialized synaptic receptors, at which the dendrite receives information from other neurons.

Front 10

Dendritic Spines

Back 10

Short outgrowths that increase the surface area available for synapses.

Front 11

Soma

Back 11

Cell body. Contains the nucleus, ribosomes, and mitochondria. Most of a neuron's metabolic work occurs here. In many neurons, the cell body is covered with synapses on its surface.

Front 12

Axon

Back 12

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

Front 13

Myelin Sheath

Back 13

Insulating material that covers the axon in vertebrates.

Front 14

Nodes of Ranvier

Back 14

Interruptions in the myelin sheath.

Front 15

Presynaptic Terminal

Back 15

(End bulb or bouton) Point where an axon releases chemicals.

Front 16

Afferent Axon

Back 16

Brings information into a structure.

Front 17

Efferent Axon

Back 17

Carries information away from a structure.

Front 18

Interneuron

Back 18

(Intrinsic neuron) Neuron whose axons and dendrites are all confined within a given structure.

Front 19

Glia

Back 19

Type of cell in the nervous system that, in contrast to other neurons, does not conduct impulses over long distances.

Front 20

Astrocytes

Back 20

Star-shaped glia that synchronize the activity of the axons.

Front 21

Microglia

Back 21

Cells that remove waste material and other microorganisms from the nervous system.

Front 22

Oligodendrocytes

Back 22

Glia cells that build myelin sheaths.

Front 23

Schwann Cells

Back 23

Glia cells that build myelin sheaths.

Front 24

Radial Glia

Back 24

Cells that guide the migration of neurons and the growth of axons and dendrites during embryological development.

Front 25

Blood-brain Barrier

Back 25

The mechanism that excludes most chemicals from the vertebrate brain.

Front 26

Active Transport

Back 26

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

Front 27

Glucose

Back 27

A sugar that vertebrate neurons depend almost entirely on.

Front 28

Thiamine

Back 28

Vitamin B that the body needs in order to use glucose.

Front 29

Electrical Gradient

Back 29

(Polarization) A difference in electrical charge between the inside and outside of the cell.

Front 30

Resting Potential

Back 30

The neuron inside the membrane has a slightly negative electrical potential with respect to the outside, mainly because of negatively charged proteins inside the cell.

Front 31

Selectively Permeable

Back 31

A membrane in which some chemicals pass through more freely than others do.

Front 32

Sodium-Potassium Pump

Back 32

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

Front 33

Concentration Gradient

Back 33

The difference in the distribution of ions across the membrane.

Front 34

Action Potentials

Back 34

Messages sent by axons.

Front 35

Hyperpolarization

Back 35

Increased polarization (increase the negative charge inside the neuron).

Front 36

Depolarize

Back 36

Reduce the neuron's polarization toward zero.

Front 37

Threshold of Excitation

Back 37

The point beyond which stimulation produces a massive depolarization of the membrane.

Front 38

Voltage-gated Channels

Back 38

Channels that regulate the sodium and potassium. Their permeability depends on the voltage difference across the membrane.

Front 39

Local anesthetic

Back 39

Attaches to the sodium channels of the membrane, preventing sodium ions from entering, and thereby stopping action potentials.

Front 40

All-or-None Law

Back 40

The amplitude and velocity of an action potential are independent of the intensity of the stimulus that initiated it, provided that the stimulus reaches the threshold.

Front 41

Refractory Period

Back 41

The period of time immediately after an action potential during which the cell resists the production of other action potentials.

Front 42

Absolute Refractory Period

Back 42

The first part of the refractory period in which the cell cannot produce an action potential, regardless of stimulation.

Front 43

Relative Refractory Period

Back 43

The second part of the refractory period in which a stronger than usual stimulus is necessary to initiate an action potential.

Front 44

Propagation of the Action Potential

Back 44

Describes the transmission of an action potential down an axon.

Front 45

Myelin

Back 45

An insulating material composed of fats and proteins.

Front 46

Myelinated Axons

Back 46

Axons covered with a myelin sheath. Covered with layers of fat and proteins.

Front 47

Saltatory Conduction

Back 47

The jumping of action potentials from node to node.

Front 48

Local Neurons

Back 48

Neurons without an axon that only exchange information with their closest neighbors and do not follow the all-or-none law.

Front 49

Graded Potential

Back 49

A membrane potential that varies in magnitude in proportion to the intensity of the stimulus.