3 - Neurophysiology: The Generation, Transmission, and Integration of Neural Signals Flashcards

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0
Q

Action potential

A

The propagated electrical message of a neuron that travels along the axon to the presynaptic axon terminals

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1
Q

Neurophysiology

A

The study of the life processes of neurons

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2
Q

Neurotransmitter

A

Also called synaptic transmitter, chemical transmitter, or simply transmitter. The chemical released from the presynaptic axon terminal that serves as the basis of communication between neurons

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3
Q

Ion

A

An atom or molecule that has acquired an electrical charge by gaining or losing one or more electrons

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4
Q

Anion

A

A negatively charged ion, such as a protein or chloride ion

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5
Q

Cation

A

A positively charged ion, such as a potassium or sodium ion

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6
Q

Intracellular fluid

A

Also called cytoplasm. The watery solution found within cells

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7
Q

Extracellular fluid

A

The fluid in the spaces between cells (interstitial fluid) and in the vascular system

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8
Q

Cell membrane

A

The lipid bilayer that ensheathes a cell

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9
Q

Microelectrode

A

An especially small electrode used to record electrical potentials from living cells

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10
Q

Resting membrane potential

A

A difference in electrical potential across the membrane of a nerve cell during an inactive period

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11
Q

Millivolt (mV)

A

A thousandth of a volt

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12
Q

Negative polarity

A

A negative electrical potential difference relative to a reference electrode

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13
Q

Lipid bilayer

A

The structure of the neuronal cell membrane, which consists of two layers of lipid molecules, within which floats various specialized proteins, such as receptors

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14
Q

Ion channel

A

A pore in the cell membrane that permits the passage of certain ions through the membrane when the channels are open

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15
Q

Gated

A

Referring to the property by which an ion channel may be opened or closed by factors such as chemicals, voltage changes, or mechanical actions

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16
Q

Potassium ion (K+)

A

A potassium atom that carries a positive charge because it has lost one electron

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17
Q

Selective permeability

A

The property of a membrane that allows some substances to pass through, but not others

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18
Q

Diffusion

A

The spontaneous spread of molecules of one substance among molecules of another substance until a uniform concentration is achieved

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19
Q

Concentration gradient

A

Variation of the concentration of a substance within a region

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20
Q

Electrostatic pressure

A

The propensity of charged molecules or ions to move, via diffusion, toward areas with the opposite charge

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21
Q

Sodium-potassium pump

A

The energetically expensive mechanism that pushes sodium ions out of a cell, a potassium ions in

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22
Q

Sodium ion (Na+)

A

A sodium atom that carries a positive charge because it has lost one electron

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23
Q

Equilibrium

A

The point at which the movement of ions across the cell membrane is balanced, as the electrostatic pressure pulling ions in one direction is offset by the diffusion force pushing them in opposite direction

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24
Q

Nernst equation

A

An equation predicting the voltage needed to just counterbalance the diffusion force pushing an ion across a semipermeable membrane from the side with a high concentration to the side with a low concentration

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25
Q

Axon hillock

A

A cone-shaped area from which the axon originates out of the cell body. Functionally, the integration zone of the neuron

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26
Q

Hyperpolarization

A

An increase in membrane potential (the interior of the neuron becomes even more negative).

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27
Q

Depolarization

A

A reduction in membrane potential (the interior of the neuron becomes less negative).

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28
Q

Local potential

A

An electrical potential that is initiated by stimulation at a specific site, which is a graded response that spreads passively across the cell membrane, decreasing in strength with time and distance

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29
Q

Threshold

A

The stimulus intensity that is just adequate to trigger an action potential at the axon hillock

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30
Q

All-or-none property

A

The fact that the amplitude of the action potential is independent of the magnitude of the stimulus

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31
Q

Afterpotential

A

The positive or negative change in membrane potential that may follow an action potential

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32
Q

Voltage-gated/sodium activated Na+ channel

A

A Na+/- selective channel that opens or closes in response to changes in the voltage of the local membrane potential; it mediates the action potential

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33
Q

Refractory

A

Transiently inactivated or exhausted

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34
Q

Absolute refractory phase

A

A brief period of complete insensitivity to stimuli

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35
Q

Relative refractory phase

A

A period of reduced sensitivity during which only strong stimulation produces an action potential

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36
Q

Channelopathy

A

A genetic abnormality of ion channels, causing a variety of symptoms

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37
Q

Tetrodotoxin (TTX)

A

A toxin from puffer fish ovaries that blocks the voltage-gated sodium channel, preventing action potential conduction

38
Q

Saxitoxin (STX)

A

An animal toxin that blocks sodium channels when applied to the outer surface of the cell membrane

39
Q

Batrachotoxin

A

A toxin, produced by poison arrow frogs, that selectively interferes with Na+ channels

40
Q

Conduction velocity

A

The speed at which an action potential is propagated along the length of an axon (or section of peripheral nerve)

41
Q

Node of Ranvier

A

A gap between successive segments of the myelin sheath where the axon membrane is exposed

42
Q

Saltatory conduction

A

The form of conduction that is characteristic of myelinated axons, in which the action potential jumps from one node of Ranvier to the next

43
Q

Postsynaptic potential

A

A local potential that is initiated by stimulation at a synapse, can vary in amplitude, and spreads passively across the cell membrane, decreasing in strength with time and distance

44
Q

Electrical synapse

A

Also called gap junction. The region between neurons where the presynaptic and postsynaptic membranes are so close that the action potential can jump to the postsynaptic membrane without first being translated into a chemical message

45
Q

Excitatory postsynaptic potential (EPSP)

A

A depolarizing potential in the postsynaptic neuron that is caused by excitatory presynaptic potentials. EPSPs increase the probability that the postsynaptic neuron will fire an action potential

46
Q

Synaptic delay

A

The brief delay between the arrival of an action potential at the axon terminal and the creation of a postsynaptic potential

47
Q

Inhibitory postsynaptic potential (IPSP)

A

A hyperpolarizing potential in the postsynaptic neuron that is caused by inhibitory connections. IPSPs decrease the probability that the postsynaptic neuron will fire an action potential

48
Q

Chloride ion (Cl-)

A

A chlorine atom that carries a negative charge because it has gained one electron

49
Q

Spatial summation

A

The summation at the axon hillock of postsynaptic potentials from across the cell body. If this summation reaches threshold, an action potential is triggered

50
Q

Temporal summation

A

The summation of postsynaptic potentials that reach the axon hillock at different times. The closer in time that the potentials occur, the more complete the summation

51
Q

Calcium ion (Ca2+)

A

A calcium atom that carries a double positive charge because it has lost two electrons

52
Q

Pinocytosis

A

The process by which synaptic neurotransmitter is repackaged into synaptic vesicles

53
Q

Ligand

A

A substance that binds to receptor molecules, such as those at the surface of the cell

54
Q

Endogenous ligand

A

Any substance, produced within the body, that selectively binds to the type of receptor that is under study

55
Q

Exogenous ligand

A

Any substance, originating from outside the body, that selectively binds to the type of receptor that is under study

56
Q

Acetylcholine (ACh)

A

A neurotransmitter produced and released by parasympathetic postganglionic neurons, by motoneurons, and by neurons throughout the brain

57
Q

Receptor molecule

A

Also called receptor. A protein that captures and reacts to molecules of a neurotransmitter or hormone

58
Q

Curare

A

An alkaloid neurotoxin that causes paralysis by blocking acetylcholine receptors in muscle

59
Q

Bungarotoxin

A

A neurotoxin, isolated from the venom of the banded krait, that selectively blocks acetylcholine receptors

60
Q

Agonist

A

A molecule, usually a drug, that binds a receptor molecule and initiates a response like that of another molecule, usually a neurotransmitter

61
Q

Antagonist

A

A molecule, usually a drug, that interferes with or prevents the action of a transmitter

62
Q

Cholinergic

A

Referring to cells that use acetylcholine as their synaptic transmitter

63
Q

Up-regulation

A

A compensatory increase in receptor availability at the synapses of a neuron

64
Q

Down-regulation

A

A compensatory reduction in receptor availability at the synapses of a neuron

65
Q

Ionotropic receptor

A

A receptor protein that includes an ion channel that is opened when the receptor is bound by an appropriate ligand

66
Q

Ligand-gated ion channel

A

Also known as chemically gated ion channel. An ion channel that opens or closes in response to the presence of a particular chemical

67
Q

Metabotropic receptor

A

A receptor protein that does not contain an ion channel but may, when activated, use a G protein system to alter the functioning of the postsynaptic cell

68
Q

G proteins

A

A class of proteins that reside next to the intracellular portion of a receptor and that are activated when the receptor binds an appropriate ligand on the extracellular surface

69
Q

Second messenger

A

A slow-acting substance in the postsynaptic cell that amplifies the effects of synaptic activity and signals synaptic activity within the postsynaptic cell

70
Q

Degradation

A

The chemical breakdown of a neurotransmitter into inactive metabolites

71
Q

Reuptake

A

The process by which released synaptic transmitter molecules are taken up and reused by the presynaptic neuron, thus stopping synaptic activity

72
Q

Transporters

A

Specialized receptors in the presynaptic membrane that recognize transmitter molecules and return them to the presynaptic neuron for reuse

73
Q

Axo-dendritic

A

Referring to a synapse in which a presynaptic axon terminal synapses onto a dendrite of the postsynaptic neuron, either via a dendritic spine or directly onto the dendrite itself

74
Q

Axo-somatic

A

Referring to a synapse in which a presynaptic axon terminal synapses onto the cell body (soma) of the postsynaptic neuron

75
Q

Axo-axonic

A

Referring to a synapse in which a presynaptic axon terminal synapses onto another axon’s terminal

76
Q

Dendro-dendritic

A

Referring to a type of synapse in which a synaptic connection forms between the dendrites of two neurons

77
Q

Retrograde synapse

A

A synapse in which a signal (usually a gas neurotransmitter) flows from the postsynaptic neuron to the presynaptic neuron, thus counter to the usual direction of synaptic communication

78
Q

Ectopic transmission

A

Cell-cell communication based on release of neurotransmitter in regions outside traditional synapses

79
Q

Varicosity

A

The axonal swelling from which neurotransmitter diffuses in a nondirected synapse

80
Q

Nondirected synapse

A

A type of synapse in which the presynaptic and postsynaptic cells are not in close apposition; instead, neurotransmitter is released by axonal varicosities and diffuses away to affect wide regions of tissue

81
Q

Neural chain

A

A simple kind of neural circuit in which neurons are attached linearly, end-to-end

82
Q

Knee jerk reflex

A

A variant of the stretch reflex in which stretching of the tendon beneath the knee leads to an upward kick of the leg

83
Q

Convergence

A

The phenomenon of neural connections in which many cells send signals to a single cell

84
Q

Divergence

A

The phenomenon of neural connections in which one cell sends signals to many other cells

85
Q

Electroencephalogram (EEG)

A

A recording of gross electrical activity of the brain recorded from large electrodes placed on the scalp

86
Q

Event-related potential (ERP)

A

Also called evoked potential. Averaged EEG recordings measuring brain responses to repeated presentations of a stimulus. Components of the ERP tend to be reliable because the background noise of the cortex has been averaged out

87
Q

Epilepsy

A

A brain disorder marked by major sudden changes in the electrophysiological state of the brain that are referred to as seizures

88
Q

Seizure

A

An epileptic episode

89
Q

Grand mal seizure

A

A type of generalized epileptic seizure in which nerve cells fire in high-frequency bursts

90
Q

Petit mal seizure

A

Also called an absence attack. A seizure that is characterized by a spike-and-wave EEG and often involves a loss of awareness and inability to recall events surrounding the seizure

91
Q

Complex partial seizure

A

In epilepsy, a type of seizure that doesn’t involve the entire brain, and therefore can cause a wide variety of symptoms

92
Q

Aura

A

In epilepsy, the unusual sensations or premonition that may precede the beginning of a seizure

93
Q

Kindling

A

A method of experimentally inducing an epileptic seizure by repeatedly stimulating a brain region