Neuroscience Ch. 3

Front 1

the action potential is also known as what?

Back 1

the nerve impulse

Front 2

do action potentials diminish over distance?

Back 2

no, they are signals of fixed size and duration

Front 3

information in action potentials is encoded in the pattern of what?

Back 3

electrical impulses

Front 4

what are cells that are capable of generating and conducting action potentials called?

Back 4

they have an excitable membrane

Front 5

what types of cells are capable of having an excitable membrane?

Back 5

nerve and muscle cells

Front 6

the "action" in action potentials occurs where?

Back 6

at the cell membrane

Front 7

the difference in electrical charge across the membrane is called?

Back 7

the resting membrane potential

Front 8

what is another name for the resting membrane potential?

Back 8

the resting potential

Front 9

the action potential is simply a brief reversal of what condition?

Back 9

the resting potential

Front 10

what is the main ingredient of fluid inside the neuron, the intracellular fluid or cytosol?

Back 10

water

Front 11

what is the fluid that bathes the neuron?

Back 11

the extracellular fluid

Front 12

what is the most important property of the water molecule?

Back 12

the uneven distribution of electrical charge

Front 13

covalent bonds means?

Back 13

they share electrons

Front 14

the oxygen atom in water acquires what type of charge?

Back 14

a net negative charge (because it has extra electrons)

Front 15

the hydrogen atoms in water acquire what type of charge?

Back 15

a net positive charge

Front 16

H20 is what type of molecule?

Back 16

a polar molecule

Front 17

atoms or molecules that have a net electrical charge are called?

Back 17

ions

Front 18

the electrical attraction of oppositely charged atoms is called?

Back 18

ionic bond

Front 19

what are the purpose of spheres of hydration?

Back 19

they are clouds of water that surround each ion and they effectively insulate the ions from one another

Front 20

the electrical charge of an atom depends on the difference between what?

Back 20

the number of protons and electrons

Front 21

ions with a difference of 1 protons or electrons is?

Back 21

monovalent

Front 22

ions with a difference of 2 protons or electrons is?

Back 22

divalent

Front 23

ions with a net positive charge are called?

Back 23

cations

Front 24

ions with a negative charge are called?

Back 24

anions

Front 25

the ions of particular importance for cellular neurophysiology are?

Back 25

the monovalent cations Na+ (sodium) and K+ (potassium) and the divalent cation Ca2+ (calcium) and the monvalent anion Cl- (chloride)

Front 26

water loving molecules are?

Back 26

hydrophilic

Front 27

compounds whose atoms are bonded by nonpolar covalent bonds have?

Back 27

no basis for chemical interactions with water

Front 28

water fearing molecules are?

Back 28

hydrophobic

Front 29

lipid

Back 29

a class of water insoluble biological molecules

Front 30

the main chemical building blocks of cell membranes are?

Back 30

phospholipids

Front 31

how are phospholipids like other lipids?

Back 31

they contain long nonpolar chains of carbon atoms bonded to hydrogen atoms

Front 32

how are phospholipids different from other lipids?

Back 32

they have a polar phosphate group (a phosphorous atom bonded to three oxygen atoms) attached to one end of the molecule

Front 33

phospholipids have what types of ends?

Back 33

a polar "head" (containing phosphate) that is hydrophilic, and a nonpolar "tail" (containing hydrocarbon) that is hydrophobic

Front 34

how is a phospholipid bilayer composed?

Back 34

hydrophilic heads face the outer and inner watery environments and the hydrophobic tails face each other

Front 35

what does a phospholipid bilayer do?

Back 35

it effectively isolates the cytosol of the neuron from the extracellular fluid

Front 36

enzymes, cytoskeleton and receptors are all made up of?

Back 36

protein molecules

Front 37

proteins are?

Back 37

molecules assembled from various combinations of 20 different amino acids

Front 38

all amino acids have what?

Back 38

a central carbon atom (the alpha atom), which is covalently bonded to four molecular groups: a hydrogen atom, an amino group, a carboxyl group, and a variable group called the r group (r for residue)

Front 39

how are proteins synthesized?

Back 39

by the ribosomes of the neuronal cell body

Front 40

what is the process of synthesizing a protein?

Back 40

amino acids assemble into a chain connected by peptide bonds, which join the amino group of one amino acid to the carboxyl group of the next

Front 41

proteins made of a single chain of amino acids are also called?

Back 41

polypeptides

Front 42

what are the four levels of protein structure?

Back 42

primary structure
secondary structure
tertiary structure
quaternary structure

Front 43

what are the structures like for a primary structure?

Back 43

like a chain, in which the amino acids are linked together by peptide bonds

Front 44

alpha helix

Back 44

a spiral-like configuration that a polypeptide chain can coil into as a protein molecule is being synthesized

Front 45

alpha helix is an example of what type of protein structure?

Back 45

a secondary structure

Front 46

the protein structure that is acquired by interaction with r groups is ?

Back 46

tertiary structure

Front 47

when different polypeptide chains can bond together to form a larger molecule, what type of protein structure does this create?

Back 47

quaternary structure

Front 48

each of the different polypeptides contributing to a protein with a quaternary structure is called?

Back 48

a subunit

Front 49

what did civilization believe before the time of Hippocrates?

Back 49

the heart was the seat of consciousness and thought

Front 50

who is the father of Western medicine?

Back 50

Hippocrates

Front 51

hippocrates believed what about the brain?

Back 51

the brain not only was involved in sensation but also was the seat of intelligence

Front 52

what did aristotle believe?

Back 52

the heart was the center of intellect and that the brain was the radiator for the cooling of blood that was overheated by the seething heart

Front 53

Galen was?

Back 53

an important figure in Roman medicine; a Greek physician;

Front 54

what did Galen believe?

Back 54

the cerebrum must be the recipinet of sensations and the cerebellum must command the muscles; sensations were registered and movements initiated by the movement of humors to or from the brain ventricles via the nerves

Front 55

the cerebrum does what?

Back 55

is a repository for memory

Front 56

what are ventricles?

Back 56

hollow spaces in the brain

Front 57

who was Descartes?

Back 57

a French mathematician and philosopher;

Front 58

what did Descartes believe?

Back 58

believed in the fluid-mechanical theory of brain function; believed that the mind is a spiritual entity that receive sensations and commands movements by communicating with the machinery of the brain via the pineal gland

Front 59

what was an important breakthrough in neuroanatomy?

Back 59

the observation that the same general pattern of bumps "gyri" and grooves "sulci" and "fissures" could be identified on the surface of the brain in every individual; those patterns enable the parceling of the cerebrum into lobes

Front 60

the nervous system consists of two divisions?

Back 60

the central nervous system and the peripheral nervous system

Front 61

what is the central nervous system?

Back 61

the brain and the spinal cord

Front 62

what is the peripheral nervous system?

Back 62

the nerves and the nerve cells that lie outside the brain and spinal cord

Front 63

what is a Sylvian fissure?

Back 63

divides the frontal lobe from the temporal lobe

Front 64

what is the central sulcus?

Back 64

divides the frontal lobe from the parietal lobe

Front 65

who learned that the nerves are 'wires' that conduct electrical signals to and from the brain?

Back 65

Luigi Galvani and Emil du Boi-Reymond

Front 66

Within each nerve of the body there are many...?

Back 66

thin filaments, or nerve fibers, each one of which could serve as an individual wire carrying information in a different direction

Front 67

What did Charles Bell and Francois Magendie do?

Back 67

showed that the two spinal roots, the dorsal root and the ventral root carry information in different directions; they experimented on animals; discovered that within each nerve there is a mixture of many wires, some of which bring information into the brain and spinal cord and others that send information out to the muscles

Front 68

Magendie later showed that?

Back 68

the dorsal roots carry sensory information to the spinal cord

Front 69

Bell proposed what about the cerebrum and cerebellum?

Back 69

that the origin of motor fibers is the cerebellum and the destination of the sensory fibers is the cerebrum

Front 70

what is the experimental ablation method?

Back 70

destroying parts of the brain to determine their function

Front 71

what is phrenology?

Back 71

developed by Franz Gall; different behavioral traits could be related to the size of different parts of the skull

Front 72

what is the inner space between the cristae called?

Back 72

matrix

Front 73

what are site of cellular respiration?

Back 73

mitochondria

Front 74

what happens when a mitochondrion inhales?

Back 74

it pulls inside pyruvic acid (derived from sugars and digested proteins and fats) and oxygen, both of which are floating in the cytosol

within the inner compartment of the mitochondrion, pyruvic acid enters into a complex series of biochemical reactions called the Krebs cycle

Front 75

what does the Krebs cycle do?

Back 75

Krebs cycle creates biochemical products that fuel the electron-transport chain and eventually yielding ATP

Front 76

how many ATP molecules are released for every molecule of pyruvic acid taken in by a mitochondrion?

Back 76

17 ATP

Front 77

when a mitochondrion exhales...?

Back 77

17 ATP molecules are released

Front 78

what does the chemical energy in ATP fuel?

Back 78

most of the biochemical reaction of the neuron

Front 79

what does the neuronal membrane do?

Back 79

serves as a barrier to enclose the cytoplasm inside the neuron and to exclude certain substances that float in the fluid that bathes the neuron

Front 80

what do some of the membrane-associated proteins do?

Back 80

pump substances from the inside to the outside; others form pores that regulate which substances can gain access to the inside of the neuron

Front 81

what is an important characteristic of neurons?

Back 81

the protein composition of the membrane varies depending on whether it is in the soma, the dendrites, or in the axon

Front 82

what is the cytoskeleton?

Back 82

it gives the neuron its characteristic shape; acts as scaffolding to the neuronal membrane

Front 83

what are the "bones" of the cytoskeleton?

Back 83

the microtubules, microfilaments and neurofilaments

Front 84

Characteristics of microtubules?

Back 84

big and run longitudinally down neurites; it appears as a straight, thick-walled hollow pipe; the wall of the pipe is composed of smaller strands that are braided like rope around the hollow core

each of the smaller strands consists of the protein tubulin

Front 85

what is a single tubulin molecule like?

Back 85

small and globular

Front 86

what is polymerization?

Back 86

the process of joining small proteins to form a long strand

the resulting strand is a polymer

Front 87

what are MAPs and what do they do?

Back 87

Microtubule-associated proteins

they participate in the regulation of microtubule assembly and function

they anchor the microtubules to one another and to other parts of the neuron

Front 88

what is tau?

Back 88

pathological changes in an axonal MAP; has been implicated in the dementia that accompanies Alzheimer's disease

Front 89

what is the severity of the dementia in Alzheimer's disease well correlated with?

Back 89

the number and distribution of what are now commonly known as neurofibrillary tangles, the "tombstones" of dead or dying neurons

Front 90

what is the first step in the process that leads to neurofibrillary tangle formation and dementia?

Back 90

the abnormal secretion of amyloid by neurons

Front 91

what are microfilaments?

Back 91

braids of two thin strands, which are made of polymers of the protein actin

Front 92

what is actin?

Back 92

a protein; and one of the most abundant in cells of all types and is believed to play a role in changing cell shape

Front 93

what do microtubules and actin microfilaments do similarly?

Back 93

they are constantly undergoing assembly and disassembly, and this process is regulated by signals in the neuron

Front 94

information about microfilaments

Back 94

they are anchored to the membrane by attachments with a meshwork of fibrous proteins that line the inside of the membrane like a spiderweb

Front 95

Neurofilaments exist ...?

Back 95

in all cells of the body as intermediate filaments; only in neurons are they called neurofilaments

Front 96

neurofilament characteristics

Back 96

consists of multiple subunits (building blocks) that are organized like a chain of sausages

Front 97

what is the internal structure of each subunit consist of?

Back 97

three protein strands woven together

Front 98

what makes up the brain's neurotransmitter systems?

Back 98

collections of cells that use a common neurotransmitter

Front 99

what are the most numerous glia in the brain?

Back 99

astrocytes

Front 100

what cells fill the spaces between neurons?

Back 100

astrocytes

Front 101

what is the primary function of oligodendroglial and Schwann cells?

Back 101

provide layers of membrane that insulate axons

Front 102

what spirals around axons in the brain?

Back 102

myelin

Front 103

what is the entire covering of the axon called?

Back 103

myelin sheath

Front 104

the region that an axonal membrane is exposed whtn the sheath is interrupted periodically is called?

Back 104

a node of Ranvier

Front 105

oligodendroglia are only found where?

Back 105

in the central nervous system

Front 106

Schwann cells are only found where?

Back 106

in the peripheral nervous system

Front 107

one oligodendroglial cell can do what?

Back 107

will contribute myelin to several axons

Front 108

this type of cells myelinates only a single axon

Back 108

schwann cell

Front 109

what provides the lining of the fluid-filled ventricles within the brain, and direct cell migration during brain development?

Back 109

Ependymal cells

Front 110

what functions as phagocytes to remove debris left by dead or degenerating neurons and glia?

Back 110

microglia

Front 111

this type of protein could be suspended in a phospholipid bilayer, with its hydrophobic portion inside the membrane and its hydrophilic ends exposed to the watery environments

Back 111

channel proteins

Front 112

what is one important property of most ion channels?

Back 112

ion selectivity

Front 113

what is an important property of many ion channels?

Back 113

gating

Front 114

channels with the gating property can be opened or closed by?

Back 114

changes in the local microenvironment of the membrane

Front 115

what do ion channels consist of?

Back 115

they consist of membrane-spanning proteins that assemble to form a pore

Front 116

what do other membrane-spanning proteins form to create?

Back 116

ion pumps

Front 117

what are enzymes that use the energy released by the breakdown of ATP to transport certain ions across the membrane?

Back 117

ion pumps

Front 118

what plays a critical role in neuronal signaling by transporting Na+ and Ca2+ from the inside of the neuron to the outside?

Back 118

ion pumps

Front 119

movement made by ions from regions of high concentration to regions of low concentration

Back 119

diffusion

Front 120

what is the difference between high and low concentration called?

Back 120

a concentration gradient

Front 121

ions will flow in which direction in a concentration gradient?

Back 121

down

Front 122

besides diffusion down a concentration gradient, what is another way to induce a net movement of ions in a solution?

Back 122

use an electrical field

Front 123

the movement of electrical charge is?

Back 123

electrical current

Front 124

what is the symbol for electrical current?

Back 124

I

Front 125

what is electrical current measured in?

Back 125

units called amperes (amps)

Front 126

what two factors determine how much current will flow?

Back 126

electrical potential and electrical conductance

Front 127

what is another term for electrical conductance?

Back 127

voltage

Front 128

what is the force exerted on a charged particle and it reflects the difference in charge between the anode and the cathode

Back 128

electrical potential or voltage

Front 129

the symbol for voltage

Back 129

V

Front 130

what is the relative ability of an electrical charge to migrate from one point to another

Back 130

electrical conductance

Front 131

the symbol for electrical conductance

Back 131

g

Front 132

what is electrical conductance measured in?

Back 132

units called siemens (S)

Front 133

what does conductance depend on?

Back 133

depends on the number of particles available to carry electrical charge and the ease with which these particles can travel through space

Front 134

what is electrical resistance?

Back 134

the relative inability of an electrical charge to migrate

Front 135

what is electrical resistance measured in?

Back 135

ohms

Front 136

symbol for electrical resistance?

Back 136

R

Front 137

what is the inverse of conductance?

Back 137

resistance

Front 138

current is the product of the conductance and potential difference; if the conductance is zero, no current will flow even when the potential difference is very large and also, when the potential difference is zero, no current will flow even when the conductance is very large

Back 138

ohm's law

Front 139

formula for ohm's law

Back 139

I = gV

Front 140

what is required in order to drive an ion across the membrane electrically?

Back 140

(1) the membrane possesses channels permeable to that ion, and (2) there is an electrical potential difference across the membrane

Front 141

what is the membrane potential?

Back 141

the voltage across the neuronal membrane at any moment

Front 142

the symbol for membrane potential?

Back 142

Vm

Front 143

when Vm or membrane potential is not at rest is due to?

Back 143

an action potential

Front 144

how can membrane potential be measured?

Back 144

by inserting a microelectrode into the cytosol

Front 145

a thin glass tube with an extremely fine tip that will penetrate the membrane of a neuron with minimal damage; it is filled with an electrically conductive salt solution and connected to a device called a voltmeter

Back 145

microelectrode

Front 146

what does the voltmeter measure?

Back 146

the electrical potential difference between the tip of this microelectrode and a wire placed outside of the cell

Front 147

when is an equilibrium state reached?

Back 147

when the diffusional and electrical forces are equal and opposite, and the net movement of K+ across the membrane ceases

Front 148

what is the electrical potential difference that exactly balances an ionic concentration

Back 148

an ionic equilibrium potential

Front 149

what is the symbol for electrical potential difference?

Back 149

Eion

Front 150

large changes in membrane potential are caused by?

Back 150

miniscule changes in ionic concentrations

Front 151

where does the net difference in electrical charge occur?

Back 151

the inside and outside surfaces of the membrane

Front 152

what is capacitance?

Back 152

when a membrane is said to store electrical charge it has capacitance

Front 153

ions are driven across the membrane ..?

Back 153

at a rate proportional to the difference between the membrane potential and the equilibrium potential

Front 154

what is the difference between the real membrane potential and the equilibrium potential for a particular ion called?

Back 154

the ionic driving force

Front 155

if the concentration difference across the membrane is known for an ion, then?

Back 155

an equilibrium potential can be calculated for that ion

Front 156

an impermeable membrane separates two regions:

Back 156

one of high salt concentration (outside) and the other of low salt concentration (inside)

Front 157

the Nernst equation calculates?

Back 157

the exact value of an equilibrium potential in mV

Front 158

what does the Nernst equation consider?

Back 158

the charge of the ion
the temperature
the ratio of the external and internal ion concentrations

Front 159

what is the sodium-potassium pump?

Back 159

an enzyme that breaks down ATP in the presence of internal Na+

Front 160

the Na-K pump pushes ions how?

Back 160

across the membrane against their concentration gradients

Front 161

what is a membrane-associated protein that transports ions across the membrane against their concentration gradients at the expense of metabolic energy?

Back 161

sodium-potassium pump

Front 162

what type of pump is also an enzyme that actively transports Ca2+ out of the cytosol across the cell membrane?

Back 162

the calcium pump

Front 163

characteristic of neurons:

Back 163

neurons are not permeable to only a single type of ion

Front 164

a mathematical formula that takes into consideration the relative permeability of the membrane to different ions

Back 164

Goldman equation

Front 165

Jan

Back 165

determined the amino acid sequences of a family of potassium channels; the search was conducted using the fruit fly Drosophila melanogaster

Front 166

Shaker potassium channel

Back 166

enabled researchers to find the genes for other potassium channels based on sequence similarity

Front 167

when you increase extracellular potassium it?

Back 167

depolarizes neurons

Front 168

a blood-brain barrier is what?

Back 168

a specialization of the walls of brain capillaries that limit the movement of potassium (and other bloodborne substances) into the extracellular fluid of the brain

Front 169

the neuronal membrane at rest is highly permeable to what?

Back 169

K+, owing to the presence of membrane potassium channels

Front 170

when there is a movement of K+ ions across the membrane

Back 170

they move down their concentration gradient, leaving the inside of the neuron negatively charged

Front 171

the extensive network of astrocytic processes

Back 171

helps dissipate the K+ over a large area

Front 172

the electrical potential difference across the membrane can be thought of as

Back 172

a battery whose charge is maintained by the work of the ion pumps

Front 173

Weaver rat strain

Back 173

the mutation of an amino acid in these rats allows Na+ and K+ to pass through the channel (a region of the brain important for motor function)

Front 174

what fills most of the space beween neurons?

Back 174

astrocytes

Front 175

what is a blood-brain barrier?

Back 175

a specialization of the walls of brain capillaries that limits the movement of potassium (and other bloodborne substances) into the extracellular fluid of the brain