Animal Physiology Ch. 6 Vocab

Front 1

Nonspiking release

Back 1

The release of neurotransmitter from a presynaptic neuron without action potentials; typically, graded changes in membrane potential modulate the activation of voltage-gated Ca2+ channels, and changes in the intracellular concentration of free Ca2+ modulate the release of transmitter.

Front 2

Cholinergic

Back 2

Pertaining to acetylcholine or substances with actions similar to that of ACh.

Front 3

Adrenergic neurons

Back 3

Neurons that use norepinephrine (or epinephrine) as transmitters

Front 4

Muscarinic AChRs

Back 4

Muscarine, a toxing isolated from some kinds of mushrooms, activates the other type of AChR, which is found in the target cells of parasympathetic neurons in the vertebrate autonomic nervous system. These AChRs are called muscarinic AChRs.

Front 5

Ionotropic glutamate receptors (iGluRs)

Back 5

A glutamate receptor that includes an ion channel in the protein complex and produces excitatory neurotransmission. See also metabotropic glutamate receptor.

Front 6

G Proteins

Back 6

A GTP-binding protein that plays a crucial role in signal transduction pathways across membranes.

Front 7

Metabotropic glutamate receptors (mGluRs)

Back 7

A G protein-linked glutamate receptor that lacks an ion channel in the receptor protein complex. See also ionotropic glutamate receptor.

Front 8

Neuromodulation

Back 8

A change in neuronal function caused by chemical messengers (neuromodulators) that are released from axon terminals but that diffuse more widely than do typical neurotransmitters; neuromodulatory effects can be relatively long-lasting.

Front 9

Synaptic plasticity

Back 9

The capacity for long-lasting or permanent changes in synaptic efficacy as a result of experience.

Front 10

Synaptic summation

Back 10

The integration of multiple postsynaptic potentials, resulting in a change in Vm in a postsynaptic neuron.

Front 11

Spatial summation

Back 11

The integration by a postsynaptic neuron of simultaneous synaptic potentials that arise from the terminals of different presynaptic neurons.

Front 12

Temporal summation

Back 12

The summation of postsynaptic membrane potentials that are elicited close to one another in time.

Front 13

Neuronal plasticity

Back 13

The capacity for modification of the activity in a neuronal circuit based on experience and changes in input.

Front 14

Homosynaptic modulation

Back 14

A change in the efficacy of a synapse that results from activity at the synapse.

Front 15

Heterosynaptic modulation

Back 15

A change in the efficacy of synaptic transmission at one synapse that is due to activity at another, separate synapse.

Front 16

Synaptic facilitation

Back 16

An increase in synaptic efficacy.

Front 17

Synaptic depression

Back 17

A decrease in synaptic efficacy following prolonged, high-frequency stimulation.

Front 18

Posttetanic potentiation

Back 18

Increased efficacy of synaptic transmission following presynaptic stimulation at a high frequency; often follows posttetanic depression.

Front 19

Heterosynaptic facilitation

Back 19

Increased efficacy of synaptic transmission between two neurons as a result of activity in a third neuron.

Front 20

Long-term potentiation (LTP)

Back 20

An increase in synaptic efficacy that develops as a result of sustained synaptic input and that lasts for a relatively long time – even days, weeks, or months.

Front 21

Long-term depression (LTD)

Back 21

A decrease in synaptic efficacy that develops as a result of sustained synaptic input and that lasts for a relatively long time – even days, weeks, or months

Front 22

Endogenous opioids

Back 22

Neurotransmitter of neuromodulator molecules (e.g., endorphins and enkephalins) whose receptors also bind opioid drugs, such as opium and heroin.

Front 23

Receptor potential

Back 23

A change in membrane potential elicited in sensory receptor cells by sensory stimulation, which changes the flow of ionic current across the plasma membrane.

Front 24

Postsynaptic current (psc)

Back 24

A change in the rate of ion flow across a postsynaptic membrane in response to a synaptic signal.

Front 25

Passive electrotonic (decremental) transmission

Back 25

See decremental transmission. Electrical signal transmission in which signals are conducted, but not regeneratively, so that their amplitude drops with distance traveled.

Front 26

Neurotransmitters

Back 26

A chemical messenger that is released by a presynaptic nerve ending and that interacts with receptor molecules in the postsynaptic membrane.

Front 27

Postsynaptic neuron

Back 27

neuron that conducts information away from a synapse

Front 28

Presynaptic neuron

Back 28

Neuron that conducts action potentials toward a synapse

Front 29

Postsynaptic potential (psp)

Back 29

A change in Vm in a postsynaptic neuron in response to a synaptic signal.

Front 30

Cable properties

Back 30

The passive electrical properties (resistance and capacitance) of a cell; the physics of transmission through long, narrow cylinders was first worked out for submarine cables, hence the name

Front 31

Length constant

Back 31

(ë) The distance along a cell over which a potential change decays in amplitude by (1-1/e), or 63%

Front 32

Nonspiking neurons

Back 32

A neuron that receives and transmits information without action potentials

Front 33

Myelin

Back 33

Myelin sheath – a membranous sheath formed by Schwann cells or oligodendrocytes that are wrapped tightly around segments of a vertebrate axon; serves as electrical insulation in salutatory conduction.

Front 34

Nodes of ranvier

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One of the regularly spaced interruptions of the myelin sheath along an axon

Front 35

Saltatory conduction

Back 35

Discontinuous conduction of action potentials that takes place at the nodes of Ranvier in myelinated axons.

Front 36

Electrical synapses

Back 36

A junction between two cells at which a signal is carried from one cell to the other by the passage of ions through gap junctions.

Front 37

Chemical synapses

Back 37

A junction between a neuron and another cell in which the signal from the presynaptic neuron is carried across the synaptic cleft by neurotransmitter molecules.

Front 38

Synaptic cleft

Back 38

The thin space separating the cells at a synapse.

Front 39

Neuromuscular junctions

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(motor endplate) the synapse that connects a motor neuron with a skeletal muscle fiber.

Front 40

Gap junctions

Back 40

Specialized cell junctions that allow for electrical coupling between cells, in which plasma membranes about 2nm apart are linked by tubular assemblies of proteins that are called connexons in vertebrates.

Front 41

Fast (direct) chemical synaptic transmission

Back 41

Synaptic transmission at a chemical synapse mediated by neurotransmitters that bind to receptor protein complexes in the postsynaptic membrane, each of which includes an ion channel. Binding of the transmitter to the receptor complex in sufficient to open (or to close) the channel.

Front 42

Excitatory postsynaptic potential (epsp)

Back 42

A change in the membrane potential of a postsynaptic cell that increases the probability of an action potential in that cell

Front 43

Slow (indirect) chemical synaptic transmission

Back 43

Synaptic transmission at a chemical synapse mediated by neurotransmitters that bind to receptor molecules in the postsynaptic membrane and activate intracellular second-messenger systems, typically through G proteins.

Front 44

Endplate potentials (epps)

Back 44

A postsynaptic potential in a muscle fiber at the neuromuscular junction (or motor endplate)

Front 45

Inhibitory postsynaptic potential (ipsp)

Back 45

A change in the transmembrane potential of a post synaptic cell that reduces the probability of an action potential in that cell.

Front 46

Presynaptic inhibition

Back 46

Neuronal inhibition resulting from the action of an inhibitory terminal that synapses on the presynaptic terminal of an excitatory synapse, which reduces the amount of transmitter released.

Front 47

Synaptic efficacy

Back 47

The effectiveness of a presynaptic impulse in producing a postsynaptic potential change.

Front 48

Miniature endplate potentials (mepps)

Back 48

A tiny depolarization (generally 1mV or less) of the postsynaptic membrane at a neuromuscular junction (motor endplate); produced by presynaptic release of a single packet of transmitter.

Front 49

Quantal release

Back 49

The release of neurotransmitter in discrete packets that correspond to vesicles containing transmitter molecules.

Front 50

Synaptic desensitization

Back 50

The failure of a postsynaptic membrane to respond to neurotransmitter due to the inactivation or loss of postsynaptic receptor molecules.

Front 51

Nicotinic AChRs

Back 51

Nicotine, an alkaloid produced by tobacco and some other plants, mimics the action of ACh on the channels found at the vertebrate neuromuscular junction and on postganglionic cells of the vertebrate autonomic nervous system, so these ACh receptors (AChRs) are called nicotinic AChRs.