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Human basic neuroscience > Cellular neurobiology > Flashcards

Cellular neurobiology Flashcards

1
Q

Name the differentiated classes of Glia Cells and their function

A

Astrocyte

Oligodendrocyte

Microglial cell

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2
Q

What are the passive properties of nerve cells

A

Passive properties refer to the capacitative and resistive aspects inherent in neuronal membranes, along with the resistivity inherent in the cytoplasm and the extracellular milieu.

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3
Q

What determines the resting membrane potential?

A

The RMP is set by a combined flux of Na and K ions

The RMP influences the direction of ion flux through ion channels

All neurons have a RMP around -65 mV.

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4
Q

Name the classes of ion channels and their properties

A

Non-gated ion channels

  • Always open
  • Leak channels
  • Maintain the resting membrane potential

Gated ion channels

  • Open and close in response to a specific stimulus
  • Transition between closed and open states = Gating
  • Synaptic potentials, Action potentials
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5
Q

What is a Ligand-gated ion channel?

A

Responds to transmitter substance and directly affects gated synaptic transmission

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6
Q

What is a phosphorylation-gated ion channel?

A

Responds to phosphorylation and affects 2nd messenger mediated synaptic transmission

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7
Q

what characterizes voltage-gated ion channels?

A

Responds to change in membrane potential and generates action potential

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8
Q

Describe the membrane time constant

A

Membrane time constant is the time for the potential to fall from the resting to a fraction (1-l/e), or 63%, of its final value in the charging curve during the application of a small negative current pulse. Negative voltage shift from the resting potential hardly activates any voltage-dependent ion channel, resulting in nominal changes in cell membrane resistance.

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9
Q

What determines the decay time of the action potential?

A

The time constant of the neuron.

Short time constant = fast decay

Long time constant = slow decay

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10
Q

Summation

A

The addition in space and time of sequential synaptic potentials to generate a postsynaptic response larger than that produced by a single synaptic potential.

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11
Q

How can synapses transmit information if their PSPs are subthreshold?

A

The answer is that neurons in the central nervous system are typically innervated by thousands of synapses, and the PSPs produced by each active synapse can sum together—in space and in time—to determine the behaviour of the postsynaptic neuron.

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12
Q

Describe the space constant

A

The space constant depends on the ratio of the membrane resistance to the axial resistance (resistance of the axoplasm). You can change the membrane’s passive resistance by changing leakage conductance in this panel to determine how such changes affect passive decay.

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13
Q

glia cell

A

most numerous type of cell in the nervous system, 3:1 ratio to neurons, responsible for supporting neurons

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14
Q

dendrite

A

extension of a neuron that receives input from axons of other cells and conducts signal towards cell body

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15
Q

interneurons

A

neurons within the brain and spinal cord that communicate internally and intervene between the sensory inputs and motor outputs

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16
Q

action potential

A

electrical signal that is carried down the axon

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17
Q

chemical synapse

A

synapses where information is transmitted via the secretion of signaling molecules (neurotransmitters)

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18
Q

synaptic vessicles

A

small sacs containing neurotransmitters at presynaptic terminal

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19
Q

dorsal root ganglia

A

contain cell bodies of sensory neurons

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20
Q

cranial nerve ganglia

A

The sensory ganglia associated with the cranial nerves; these correspond to the dorsal root ganglia of the segmental nerves of the spinal cord.

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21
Q

extracellular recording

A

Method of taking measurements of cell firing by inserting a fine-tipped electrode into the extracellular fluid surrounding the cell…good for temporal resolution of action potentials

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22
Q

intracellular recording

A

Method of taking measurements of cell firing by inserting a fine-tipped electrode into the cell…good for resolution of receptor potentials or synaptic potentials

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23
Q

receptor potential

A

A slow, graded electrical potential produced by a receptor cell in response to a physical stimulus

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24
Q

synaptic potential

A

Graded potentials produced in the post-synaptic cell in response to neurotransmitters binding to receptors

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25
Q

Visceral or autonomic motor division

A

sympathetic, parasympathetic, and enteric divisions…innervate smooth muscles, cardiac muscle, and glands

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26
Q

sympathetic division

A

The part of the autonomic nervous system that arouses the body to deal with perceived threats.

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27
Q

parasympathetic nervous system

A

the division of the autonomic nervous system that calms the body, conserving its energy

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28
Q

enteric system

A

A subsystem of the visceral motor system, made up of small ganglia and individual neurons scattered throughout the wall of the gut; influences gastric motility and secretion.

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29
Q

active transporters

A

Transmembrane proteins that actively move ions into or out of cells against their concentration gradients. Their source of energy may be ATP or the electrochemical gradients of various ions.

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30
Q

depolarization

A

Displacement of a cell’s membrane potential toward a less negative value.

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31
Q

electrochemical equilibrium

A

The condition in which no net ionic flux occurs across a membrane because ion concentration gradients and opposing transmembrane potentials are in exact balance.

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32
Q

equilibrium potential

A

The membrane potential at which a given ion is in electrochemical equilibrium.

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33
Q

hyperpolarization

A

The displacement of a cell’s membrane potential toward a more negative value.

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34
Q

ion channels

A

Integral membrane proteins possessing pores that allow only certain ions to diffuse across cell membranes, thereby conferring selective ionic permeability.

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35
Q

Nernst equation

A

A mathematical formula that predicts the electrical potential generated ionically across a membrane at electrochemical equilibrium.

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36
Q

overshoot phase

A

The peak, positive-going phase of an action potential, caused by high membrane permeability to a cation such as Na+ or Ca2+.

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37
Q

passive flow

A

The flow of electrical current across neuronal membranes that does not entail the action potential mechanism.

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38
Q

receptor potential

A

The membrane potential change elicited in receptor neurons during sensory transduction. Also called generator potential.

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39
Q

rising phase

A

The initial, depolarizing, phase of an action potential, caused by the regenerative, voltage-dependent influx of a cation such as Na+ or Ca2+.

40
Q

threshold potential

A

The level of membrane potential at which an action potential is generated.

41
Q

undershoot

A

The final, hyperpolarizing phase of an action potential, typically caused by the voltage-dependent efflux of a cation such as K+.

42
Q

active transporters

A

Transmembrane proteins that actively move ions into or out of cells against their concentration gradients. Their source of energy may be ATP or the electrochemical gradients of various ions.

43
Q

ATPase pumps

A

Membrane pumps that use the hydrolysis of ATP to translocate ions against their electrochemical gradients.

44
Q

co-transporters

A

Active transporters that use the energy from ionic gradients to carry multiple ions across the membrane in the same direction.

45
Q

electrogenic

A

Capable of generating an electrical current; usually applied to membrane transporters that create electrical currents while translocating ions.

46
Q

ion exchangers

A

Membrane transporters that exchange intracellular and extracellular ions against their concentration gradient by using the electrochemical gradient of other ions as an energy source.

47
Q

ligand-gated ion channels

A

Ion channels that respond to chemical signals rather than to the changes in membrane potential generated by ionic gradients. The term covers a large group of neurotransmitter receptors that combine receptor and ion channel functions into a single molecule.

48
Q

macroscopic currents

A

Ionic currents flowing through large numbers of ion channels distributed over a substantial area of membrane.

49
Q

microscopic currents

A

Ionic currents flowing through single ion channels.

50
Q

patch clamp

A

An extraordinarily sensitive voltage clamp method that permits the measurement of ionic currents flowing through individual ion channels.

51
Q

pore

A

Structural feature of an ion channel that allows ions to diffuse through the channel.

52
Q

pore loop

A

An extracellular domain of amino acids, found in certain ion channels, that lines the channel pore and allows only certain ions to pass.

53
Q

voltage-gated

A

Term used to describe ion channels whose opening and closing is sensitive to membrane potential.

54
Q

acetylcholine

A

Neurotransmitter at motor neuron synapses, in autonomic ganglia, and in a variety of central synapses. Binds to two types of acetylcholine receptors (AChRs), either ligand-gated ion channels (nicotinic receptors) and G-protein-coupled receptors (muscarinic receptors).

55
Q

clathrin

A

The most important protein for endocytotic budding of vesicles from the plasma membrane; its three-pronged “triskelia” attach to the vesicular membrane to be retrieved.

56
Q

co-transmitters

A

Two or more types of neurotransmitters within a single synapse; may be packaged into separate populations of synaptic vesicles or co-localized within the same synaptic vesicles.

57
Q

connexons

A

Precisely aligned, paired transmembrane channels that form gap junctions between cells. They are formed from connexins, members of a specialized family of channel proteins.

58
Q

end plate current (EPC)

A

A macroscopic postsynaptic current resulting from the summed opening of many ion channels; produced by neurotransmitter release and binding at the motor end plate.

59
Q

end plate potential (EPP)

A

Depolarization of the membrane potential of skeletal muscle fiber, caused by the action of the transmitter acetylcholine at the neuromuscular synapse.

60
Q

end plate

A

The complex postsynaptic specialization at the site of nerve contact on skeletal muscle fibers.

61
Q

excitatory postsynaptic potential (EPSP)

A

Neurotransmitter-induced postsynaptic potential change that depolarizes the cell, and hence increases the likelihood of initiating an action potential.

62
Q

G-protein-coupled receptors

A

A large family of neurotransmitter or hormone receptors, characterized by seven transmembrane domains; the binding of these receptors by agonists leads to the activation of intracellular G-proteins.

63
Q

G-proteins

A

Proteins that are activated by exchanging bound GDP for bound GTP (and thus also known as GTP-binding proteins).

64
Q

gap junction

A

A specialized intercellular contact formed by channels that directly connect the cytoplasm of two cells.

65
Q

inhibitory postsynaptic potential (IPSP)

A

Neurotransmitter-induced postsynaptic potential change that tends to decrease the likelihood of a postsynaptic action potential.

66
Q

ionotropic receptors

A

Receptors in which the ligand binding site is an integral part of the receptor molecule.

67
Q

ligand-gated ion channels

A

Ion channels that respond to chemical signals rather than to the changes in membrane potential generated by ionic gradients. The term covers a large group of neurotransmitter receptors that combine receptor and ion channel functions into a single molecule.

68
Q

miniature end plate potential (MEPP)

A

Small, spontaneous depolarization of the membrane potential of skeletal muscle cells, caused by the release of a single quantum of acetylcholine.

69
Q

metabotropic receptors

A

Receptors that are indirectly activated by the action of neurotransmitters or other extracellular signals, typically through the aegis of G-protein activation. Also called G-protein-coupled receptors.

70
Q

neurotransmitter

A

Substance released by synaptic terminals for the purpose of transmitting information from one cell (the presynaptic cell) to another (the postsynaptic cell).

71
Q

postsynaptic

A

Referring to the component of a synapse specialized for transmitter reception; downstream at a synapse.

72
Q

postsynaptic current (PSC)

A

The current produced in a postsynaptic neuron by the binding of neurotransmitter released from a presynaptic neuron.

73
Q

postsynaptic potential (PSP)

A

The potential change produced in a postsynaptic neuron by the binding of neurotransmitter released from a presynaptic neuron.

74
Q

presynaptic

A

Referring to the component of a synapse specialized for transmitter release; upstream at a synapse.

75
Q

reversal potential

A

Membrane potential of a postsynaptic neuron (or other target cell) at which the action of a given neurotransmitter causes no net current flow.

76
Q

summation

A

The addition in space and time of sequential synaptic potentials to generate a larger than normal postsynaptic response.

77
Q

synaptic cleft

A

The space that separates pre- and postsynaptic neurons at chemical synapses.

78
Q

synaptic vesicle cycling

A

Sequence of budding and fusion reactions that occurs in presynaptic terminals to maintain the supply of synaptic vesicles.

79
Q

saltatory conduction

A

Mechanism of action potential propagation in myelinated axons; so named because action potentials “jump” from one node of Ranvier to the next due to generation of action potentials only at these sites.

80
Q

The relative refractory period is dependent on..

A

K+ channels

81
Q

What is true about the resting membrane potential?

A

It depends on the intracellular and extracellular K+ concentration

82
Q

What is true about the action potential?

A

The early afterhyperpolarization regulates the frequency of action potentials

83
Q

What is true about the neuron´s electrical properties?

A
  1. Synaptic summation depends on the time constant
  2. Synaptic summation depends on the space constant
84
Q

What is true about the neuron´s electrical properties?

A

Inhibitory synapses occur frequently on the soma and proximal dendrites

Excitatory synapses occur frequently on distal dendrites

85
Q

What is true about excitability?

A

Excitability depends on voltage-gated ion channels

86
Q

What is true about ion channels?

A

Ligand-gated channels occur in cell bodies

Leak channels determine the resting membrane potential

87
Q

What is true about electrical synapses?

A

They contain connexin

88
Q

What is true about synaptic vesicles?

A

Large dense cored vesicles are not recycled in nerve terminals

89
Q

channel selectivity

A

This is the principle that only certain ions will pass a channel. This can be due to charge of the ion, size of the molecule, or whether the ion gathers water molecules around itself (hydration, making it bigger).

90
Q

Voltage across the membrane is a form of energy that cells use to move things. What is the ultimate source of that energy?

A

Metabolism that generates ATP molecules that run the sodium/potassium ATPase pump.

91
Q

What is the mechanism for selectivity in voltage-gated ion channels?

A

Selectivity in most ion channels is based on interaction between the ions to which the channel is permeable and amino acids in the channel pore. Factors that are important include size and charge of the ion, and whether the ion is strongly attracted to water molecules (hydrated). If the hydrated diameter is too large for the pore, it must interact with molecules in the channel to break the connection with water molecules if it is to pass. Many channels have loops of amino acids that extend into the channel that provide the selectivity filter.

92
Q

How are some voltage-gated ion channels inactivated?

A

Several voltage-gated channels inactivate after being activated. A classic example of this is the voltage gated fast sodium channel. There is a segment of the amino acid chain of the channel protein that enters the pore and blocks further ion movement after the initial activation of the channel. This inactivation “gate” will be reopened once the cell has repolarized.

93
Q

What is responsible for the rising (depolarizing) phase of the action potential?

A

nce the neuron reaches threshold, the rising (depolarizing) phase of the action potential is due to the conformation change in the fast sodium channel once threshold is reached, with the rapid influx of some sodium ions.

94
Q

What are the two processes that contribute to the falling (repolarizing) phase of the action potential?

A

The rapid repolarization of a neuron once an action potential has been generated is due to the very rapid inactivation of fast sodium channels along with activation of the slower responding voltage-gated potassium channels.

95
Q
A

Human basic neuroscience (68 decks)

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