Ch 41-2

Front 1

Volts

Back 1

Measurement of electrical force

Front 2

Polarized

Back 2

Situation when positive and negative forces are separated by a plasma membrane

Front 3

Membrane Potential

Back 3

The difference between the electrical charges along the inside and outside surfaces of a cell membrane

Front 4

Resting Potential

Back 4

The imbalance of electrical charge that exists between the interior of electrically excitable nerve cells and their environment

Front 5

Electrochemical Gradient

Back 5

A difference in ion concentration between two points so that ions tend to move PASSIVELY along it.

Front 6

Equilibrium Potential

Back 6

The membrane potential at which a given neurotransmitter causes no net current flow of ions through that neurotransmitter receptor's ion channel; also known as Nernst or Reversal Potential.

Front 7

Nernst Equation

Back 7

E=60mV log ([X extracellular]/[Xintracellular])

Front 8

Depolarization

Back 8

Change in the membrane potential that occurs when the cell membrane becomes less polarized, that is, less negative inside the cell relative to the surrounding fluid.

Front 9

Hyperpolarization

Back 9

Change in the membrane potential that occurs when the cell membrane becomes more polarized, that is, more negative relative to the extracellular fluid.

Front 10

Excitable Cells

Back 10

The term used to describe neurons and muscle cells because they have the capacity to generate electrical signals.

Front 11

Voltage-gated Ion Channels

Back 11

Ion channels that open and close in response to changes in the amount of electric charge across a membrane.

Front 12

Ligand-gated Ion Channel

Back 12

A type of cell surface receptor that binds a ligand and functions as an ion channel. Ligand binding either opens or closes a channel.

Front 13

Action Potential

Back 13

An electrical signal along a cell's plasma membrane; occurs in animal neuron axons muscle cells and some plant cells.

Front 14

Threshold Potential

Back 14

The membrane potential, typically around −50mV, which is sufficient to trigger an action potential in an electrically excitable cell such as a neuron.

Front 15

Inactivation Gate

Back 15

A string of amino acids that juts out from a channel protein into the cytosol and blocks the movement of ions through the channel.

Front 16

Absolute Refractory Period

Back 16

The period during an action potential when the inactivation gate of the voltage-gated sodium channel is closed; during this time, it is impossible to generate another action potential.

Front 17

Relative Refractory Period

Back 17

The period near the end of an action potential when voltage-gated potassium channels are still open; during this time a new action potential can be generated if a stimulus is sufficiently strong to raise the membrane potential to threshold.

Front 18

Saltatory Conduction

Back 18

The conduction of an action potential along an axon in which the action potential is regenerated at each node of Ranvier instead of along the entire length of the axon.

Front 19

Synapse

Back 19

A junction where a nerve terminal meets a target neuron, muscle cell, or gland and through which an electrical or chemical signal passes.

Front 20

Synaptic Cleft

Back 20

The extracellular space between a neuron and its target cell.

Front 21

Presynaptic Cell

Back 21

The neuron that sends an electrical or chemical signal to another cell.

Front 22

Postsynaptic Cell

Back 22

The cell that receives the electrical or chemical signal sent from a neuron.

Front 23

Electrical Synapse

Back 23

A synapse that directly passes electric current from the presynaptic to the postsynaptic cell via gap junctions.

Front 24

Chemical Synapse

Back 24

A synapse in which a chemical called a neurotransmitter is released from the axon terminal of a neuron and acts as a signal from the presynaptic to the postsynaptic cell.

Front 25

Neurotransmitter

Back 25

A small signaling molecule that is released from an axon terminal and diffuses to a postsynaptic cell where it elicits a response.

Front 26

Excitatory Postsynaptic Potential (EPSP)

Back 26

The response from an excitatory neurotransmitter that depolarizes the postsynaptic membrane; the depolarization brings the membrane potential closer to the threshold potential that would trigger an action potential.

Front 27

Inhibitory Postsynaptic Potential (IPSP)

Back 27

The response from an inhibitory neurotransmitter that hyperpolarizes the postsynaptic membrane; this hyperpolarization reduces the likelihood of an action potential.

Front 28

Spatial Summation

Back 28

Occurs when two or more postsynaptic potentials are generated at one time along different regions of the dendrites and their depolarizations and hyperpolarizations sum together.

Front 29

Temporal Summation

Back 29

Occurs when two or more postsynaptic potentials arrive at the same location in a dendrite in quick succession and their depolarizations and hyperpolarizations sum together.

Front 30

Neuromuscular Junction

Back 30

The point of contact between a motor neuron's axon and a skeletal or cardiac muscle fiber.

Front 31

Neuromodulator

Back 31

Another term for a neuropeptide, which is a neurotransmitter that can alter or modulate the response of a postsynaptic neuron to other neurotransmitters.

Front 32

Metabotropic Receptor

Back 32

A G-protein-coupled receptor that initiates a signaling pathway in response to a neurotransmitter. One of two types of postsynaptic receptors, the other being an ionotropic receptor.

Front 33

Ionotropic Receptor

Back 33

One of two types of postsynaptic receptors, the other being a metabotropic receptor. Consists of a ligand-gated ion channel that opens in response to binding of a neurotransmitter.

Front 34

GABA-A receptor

Back 34

Cell surface proteins which bind GAMMA-A and control an integral membrane chloride channel; most prevalent inhibitory neurotransmitter receptor in the brain.

Front 35

Bipolar Disorder

Back 35

A neurological disorder characterized by alternating periods of euphoria and depression, resulting from an imbalance in neurotransmitter levels in the brain.

Front 36

Major Depressive Disorder

Back 36

A neurological disorder characterized by feelings of despair and sadness, resulting from an imbalance in neurotransmitter levels in the brain.

Front 37

Selective Serotonin Reuptake Inhibitors

Back 37

Drugs used to treat major depressive disorder that act by increasing concentrations of serotonin in the brain.

Front 38

Congenital Hypothyroidism

Back 38

A condition characterized by poor differentiation of the central nervous system due to a failure of neurons to become myelinated in fetal development; results in profound mental defects.

Front 39

Multiple Sclerosis (MS)

Back 39

A disease in which the patient's own body attacks and destroys myelin as if it were a foreign substance; impairs the function of myelinated neurons that control movement, speech, memory, and emotion.