How do neurons use electrical activity to transmit information?

Question 1

back propagation

Answer 1

Reverse movement of an action potential into the dendritic field of a neuron; postulated to play a role in plastic changes that underlie learning.

Question 1

concentration gradient

Answer 1

Differences in concentration of a substance among regions of a container that allow the substance to diffuse from an area of higher concentration to an area of lower concentration.

Question 2

microelectrode

Answer 2

A microscopic insulated wire or a salt-water-filled glass tube of which the uninsulated tip is used to stimulate or record from neurons.

Question 3

graded potential

Answer 3

Small voltage fluctuation in the cell membrane restricted to the vicinity on the axon where ion concentrations change to cause a brief increase (hyperpolarization) or decrease (depolarization) in electrical charge across the cell membrane.

Question 4

depolarization

Answer 4

Decrease in electrical charge across a membrane, usually due to the inward flow of sodium ions.

Question 5

nerve impulse

Answer 5

Propagation of an action potential on the membrane of an axon.

Question 6

voltage gradient

Answer 6

Difference in charge between two regions that allows a flow of current if the two regions are connected.

Question 7

voltage-sensitive channel

Answer 7

Gated protein channel that opens or closes only at specific membrane voltages.

Question 7

voltmeter

Answer 7

Device that measures the flow and the strength of electrical voltage by recording the difference in electrical potential between two bodies.

Question 8

end plate

Answer 8

On a muscle, the receptor-ion complex that is activated by the release of the neurotransmitter acetylcholine from the terminal of a motor neuron.

Question 8

resting potential

Answer 8

Electrical charge across the cell membrane in the absence of stimulation; a store of potential energy produced by a greater negative charge on the intracellular side relative to the extracellular side.

Question 9

hyperpolarization

Answer 9

Increase in electrical charge across a membrane, usually due to the inward flow of chloride or sodium ions or the outward flow of potassium ions.

Question 10

oscilloscope

Answer 10

Device that serves as a sensitive voltmeter by registering the flow of electrons to measure voltage.

Question 11

saltatory conduction

Answer 11

Propagation of an action potential at successive nodes of Ranvier; saltatory means ‘jumping’ or ‘dancing.’

Question 12

temporal summation

Answer 12

Graded potentials that occur at approximately the same time on a membrane are summed.

Question 14

absolutely refractory

Answer 14

Refers to the state of an axon in the repolarizing period during which a new action potential cannot be elicited (with some exceptions), because gate 2 of sodium channels, which is not voltage sensitive, is closed.

Question 15

optogenetics

Answer 15

Transgenic technique that combines genetics and light to control targeted cells in living tissue.

Question 17

diffusion

Answer 17

Movement of ions from an area of higher concentration to an area of lower concentration through random motion.

Question 17

threshold potential

Answer 17

Voltage on a neural membrane at which an action potential is triggered by the opening of Na+ and K+ voltage-sensitive channels; about 250 millivolts relative to extracellular surround.

Question 18

transmitter-sensitive channel

Answer 18

Receptor complex that has both a receptor site for a chemical and a pore through which ions can flow.

Question 19

relatively refractory

Answer 19

Refers to the state of an axon in the later phase of an action potential during which increased electrical current is required to produce another action potential; a phase during which potassium channels are still open.

Question 20

excitatory postsynaptic potential (EPSP)

Answer 20

Brief depolarization of a neuron membrane in response to stimulation, making the neuron more likely to produce an action potential.

Question 21

electroencephalogram (EEG)

Answer 21

Graph that records electrical activity through the skull or from the brain and represents graded potentials of many neurons.

Question 23

electrical stimulation

Answer 23

Passage of an electrical current from the uninsulated tip of an electrode through tissue, resulting in changes in the electrical activity of the tissue.

Question 24

stretch-sensitive channel

Answer 24

Ion channel on a tactile sensory neuron that activates in response to stretching of the membrane, initiating a nerve impulse.

Question 25

action potential

Answer 25

Large, brief reversal in the polarity of an axon.

Question 27

node of Ranvier

Answer 27

The part of an axon that is not covered by myelin.

Question 28

inhibitory postsynaptic potential (IPSP)

Answer 28

Brief hyperpolarization of a neuron membrane in response to stimulation, making the neuron less likely to produce an action potential.

Question 29

autoimmune disease

Answer 29

Illness resulting from the loss of the immune system’s ability to discriminate between foreign pathogens in the body and the body itself.

Question 30

spatial summation

Answer 30

Graded potentials that occur at approximately the same location and time on a membrane are summed.