Chapter 2: Nerve Cells & Nerve Impulses

Question 1

Neurons

Answer 1

receive information and transmit it to other cells

Question 2

Santiago Ramon y Cajal

Answer 2

used newly developed staining techniques to show that a small gap separates the tips of one’s neuron’s fibers from the surface of the next neuron

Question 3

Charles Sherrington

Answer 3

widely recognized as one of the two founders of neuroscience

Question 4

Membrane

Answer 4

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

* plasma membrane

Question 5

Neucleus

Answer 5

the structure that contains the chromosomes

Question 6

Mitochondrion

Answer 6

the structure that performs metabolic activities, providing the energy that the cell requires for all other activities

Question 7

Ribosomes

Answer 7

the sites at which the cell synthesizes new protein molecules

Question 8

Endoplasmic reticulum

Answer 8

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

Question 9

Motor neuron

Answer 9

receives excitation from other neurons through it’s dendrites and conducts impulses along it’s axon to a muscle

*has it’s soma in the spinal cord

Question 10

Sensory neuron

Answer 10

specialized at one end to be highly sensitive to a sensitive to a particular type of stimulation, such as light, sound or touch

Question 11

Dendrites

Answer 11

branching fibers that receive information from other neurons

Question 12

Dendritic spines

Answer 12

the short outgrowth that increase the surface area available for synapses

Question 13

Cell body (soma)

Answer 13

contains the nucleus, ribosomes, and mitochondria * most of the metabolic work of the neuron occurs here

Question 14

Axon

Answer 14

a thin fiber of constant diameter, in most cases longer than the dendrites

Question 15

Myelin sheath

Answer 15

an insulating material

Question 16

rodes of Ranvier

Answer 16

interruptions in the myelin sheath of vertebrate axons

Question 17

Presynaptic terminal

Answer 17

the point from which the axon releases chemicals that cross through the junction between one neuron and the next * also known as end bulb & button

Question 18

Afferent axon

Answer 18

brings information into a structure (exits)

Question 19

Efferent axon

Answer 19

carries information away from the structure (admit)

Question 20

Interneurons/Intristic neuron

Answer 20

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

Question 21

Glia

Answer 21

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

Question 22

Astrocytes

Answer 22

a star-shaped glia that synchronizes the activity of the axons

Question 23

Microglia

Answer 23

cells that remove waste material and other microorganisms from the nervous system

Question 24

Oligodendrocytes

Answer 24

glia cells that build myelin sheaths

Question 25

Schwann Cells

Answer 25

glia cells that build myelin sheaths

Question 26

Radial glia

Answer 26

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

Question 27

Blood-brain barrier

Answer 27

mechanism that excludes most chemicals from the brain

Question 28

Active transport

Answer 28

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

Question 29

Glucose

Answer 29

sugar; vertebrate neurons depend almost entirely on glucose

Question 30

thiamine

Answer 30

B1 vitamin necessary to use glucose

Question 31

electrical gradient (polarization)

Answer 31

a difference in electrical charge between the inside and outside of the cell

Question 32

resting potential

Answer 32

the difference in voltage in a resting neuron

Question 33

selective permeable

Answer 33

some chemicals pass through it more freely than others do

Question 34

sodium-potassium pump

Answer 34

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

Question 35

concentration gradient

Answer 35

the difference in distribution of ions across the membrane

Question 36

Action potentials

Answer 36

messages sent by axons

Question 37

hyperpolarization

Answer 37

increased polarization across a membrane

Question 38

depolarization

Answer 38

to reduce polarization toward zero across a membrane

Question 39

threshold of excitation

Answer 39

minimum amount of membrane depolarization necessary to trigger an action potential

Question 40

Voltage-aged channels

Answer 40

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

Question 41

all-or-none law

Answer 41

principle that the amplitude and velocity of an action potential are independent of the stimulus that initiated it

Question 42

refractory period

Answer 42

time when the cell resists the production of further action potentials

Question 43

Absolute refractory period

Answer 43

a time when the membrane is unable to produce an action potential

Question 44

relative refractory period

Answer 44

time after the absolute refractory period that requires a stronger stimulus to mitiate an action potential

Question 45

Propagation of the action potential

Answer 45

transmission of an action potential down an axon

Question 46

Axon hillcock

Answer 46

a swelling where the axon exits the cell body

Question 47

Myelin

Answer 47

an insulating material composed of fats and proteins

Question 48

Myelinated axons

Answer 48

axons covered with myelin sheaths

Question 49

Saltatory conduction

Answer 49

the jumping of action potentials from node to node

Question 50

Local neurons

Answer 50

neurons w/o an axon

Question 51

graded potential

Answer 51

a membrane potential that varies in magnitude in proportion to the intenisty of the stimulus