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Physiology > Lecture 2 > Flashcards

Lecture 2 Flashcards

1
Q

Another name for the specific electrical potential (voltage) created by ions in and out of a cell:

A

Nernst or equilibrium potential for the ion

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2
Q

T or F? Opening K+ channels will depolarize the cell.

A

F. Hyperpolarize

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3
Q

Will opening the Na+ channels depolarize or hyper polarize the cell?

A

depolarize

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4
Q

When is there a driving force on the ion to move it in or out of the cell?

A

When the cell voltage is not the same as the ion’s Nernst potential

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5
Q

Another name for Nernst potential:

A

equilibrium potential

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6
Q

What factors influence the MP of the cell?

A

driving force coupled with the ion’s channel conductance

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7
Q

How are the opening and closing of channels regulated?

A

voltage-gated, ligand-gated, or other factors

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8
Q

Voltage-gated cells rely on:

A

membrane potential

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9
Q

ligand-gated channels rely on:

A

chemicals and neurotransmitters

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10
Q

What creates the negative charge inside the cell?

A

K+ leaving (he also said the Na-K pump contributes little tot the inside negative charge)

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11
Q

What two forces act on ions?

A

charge and concentration

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12
Q

T or F? At equilibrium there is no flow of ions across the membrane.

A

F. no NET flow

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13
Q

When is equilibrium reached?

A

chem force is equal and opposite in direction to the electrical force on the ion

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14
Q

T or F? When a neuron is at resting potential the Na ions are at equilibrium.

A

F

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15
Q

T or F? When a neuron is at resting potential the K ions are at equilibrium.

A

F.

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16
Q

T or F? Charged molecules are not subject to a diffusive chemical driving force.

A

F. applies to all charged and uncharged molecules

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17
Q

T or F? Uncharged molecules are not subject to as electrical driving force.

A

T.

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18
Q

Another way of saying chemical gradient:

A

Concentration gradient

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19
Q

What is the diffusion of a specific ion across the PM governed by?

A

driving force + # of open channels

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20
Q

Is the Na conc high or low inside a typical nerve cell at rest?

A

low

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21
Q

In which direction do both the chemical and electrical forces go with a typical nerve cell at rest for Na?

A

into the cell

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22
Q

In which direction do the chemical and electrical forces go with a typical nerve cell at rest for Cl-?

A

the chemical driving force is directed inside the cell and the electrical driving force is directed outside the cell

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23
Q

In which direction do the chemical and electrical forces go with a typical nerve cell at rest for K?

A

the chemical driving force is directed outside the cell and the electrical diving force is directed inside the cell

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24
Q

With which molecule are the 2 driving forces complimentary, Na, K, or Cl-?

A

Na+

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25
Q

With which molecule are the 2 driving forces offset completely, Na, K, or Cl-?

A

Cl-

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26
Q

With which molecule are the 2 driving forces offset incompletely, Na, K, or Cl-?

A

K+

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27
Q

T or F? If the concentration gradient for an ion is know, the electrical gradient (voltage) can be calculated.

A

T. With Nernst Eq.

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28
Q

Is the electrical gradient typically the same as the membrane potential for the cell?

A

No, only if this is the only permeable ion

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29
Q

In which situation would the electrical gradient be the same as the membrane potential for the cell?

A

if this is the only permeable ion

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30
Q

Eq. Pot for each ion Nernst eq:

A

V = (61/n)Xlog(Cout/Cin) (of a given ion) n = ion valence, c = concentration

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31
Q

Nernst potential for Na+ =

A

+60mV

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32
Q

Nernst potential for Cl- =

A

-63mV

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33
Q

Nernst potential for K+ =

A

-90mV

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34
Q

When the membrane conductance increases for a particular ion,:

A

the membrane potential will move toward the Nernst potential for that ion

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35
Q

In which direction will K+ flow if the cell is at -70mV inside?

A

out of the cell to try and reach its Nernst potential of -90mV

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36
Q

What are the “n” values for K+, Na+, and Cl-?

A

+1, +1, and -1

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37
Q

Ion conc.’s in and out of the cell for K+ at equilibrium:

A

5mM out, 150 mM in

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38
Q

Ion conc.’s in and out of the cell for Na+ at equilibrium:

A

145mM out, 15 mM in

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39
Q

Ion conc.’s in and out of the cell for Cl- at equilibrium:

A

108mM out, 10 mM in

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40
Q

Ion conc.’s in and out of the cell for Ca++ at equilibrium:

A

1 mM out, 0.0001 mM in

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41
Q

In which direction will Na+ flow (in or out) for a neuron resting at -60mV?

A

in to reach it’s Nernst potential of +60mV

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42
Q

In which direction will Cl- flow (in or out) for a neuron resting at -60mV?

A

in (very little) to reach it’s Nernst potential of -63mV

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43
Q

In which direction will K+ flow (in or out) for a neuron resting at -60mV?

A

out to reach it’s Nernst potential of -90mV

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44
Q

What is the driving force for K+ in a cell at -90mV?

A

zero bc that is the Nernst potential for K+, the cell is at equilibrium

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45
Q

What factors determine the total current produced by a given ion?

A

driving force and conductance

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46
Q

Equation for current produced by an ion:

A

conductance X driving force (Vm-Veq)

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47
Q

math symbol for conductance:

A

g

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48
Q

math symbol for current flow of an ion:

A

I

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49
Q

T or F? Driving force = Veq - Vm.

A

F. = Vm - Veq

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50
Q

What is the driving force of K at a RMP of 70mV? Ek = -92mV

A

-70 - (-92) = +22

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51
Q

2 meanings of conductance:

A
  1. conductance of a single channel

2. Cell conductance due to opening of a population of channels

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52
Q

How many channels and how wide the channels are:

A

conductance

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53
Q

T or F? For a cell at rest, there are few Na+ channels open and many K+ channels open

A

T

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54
Q

Will a cell have a positive or negative charge if the g(Na) > g(K)?

A

positive because the conductance for Na+ is greater

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55
Q

Will a cell have a positive or negative charge if the g(Na)

A

negative bc the conductance for K is greater

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56
Q

Will K flow in or out of a cell if the conductance of K is greater than Na?

A

out

57
Q

Will Na flow in or out of a cell if the conductance of K is greater than Na?

A

in

58
Q

Will K flow in or out of a cell if the conductance of Na is greater than K?

A

out

59
Q

Will Na flow in or out of a cell if the conductance of Na is greater than K?

A

in

60
Q

relative influence of sodium channels is:

A

gNa/(gNa + gK)

61
Q

relative influence of potassium channels is:

A

gK/ (gNa + gK)

62
Q

What channels do you want to open and which do you want to close in order for a cell to depolarize:

A

Open Na+ and close K+

63
Q

This ratio controls the MP?

A

conductance ratio

64
Q

Is GABA an inhibitory or excitatory neurotransmitter?

A

inhibitory

65
Q

Is glycine inhibitory or excitatory?

A

inhibitory

66
Q

What effect, if any, will GABA and glycine (separate questions) have on channels?

A

they both open chloride channels, inhibitin depolarization (- charge enters the cell)

67
Q

Will opened Cl- channel depolarize or hyperpolarize a cell?

A

hyperpolarize

68
Q

Why won’t a cell depolarize when the Na channels are opened after Cl- channels are opened?

A

Cl- reenters the cell, preventing depolarization

69
Q

Which has a higher conductance, Cl or Na?

A

Cl

70
Q

Which has a higher conductance, Cl or K?

A

Cl

71
Q

The opening of Cl- channels will ____ the responsiveness to Na channels.

A

shunt

72
Q

The MP of a cell is determined by:

A

the permeability of each ion (P) and the eq pot. of each ion

73
Q

Can ions flow against their electrochemical gradient in facilitated diffusion?

A

No

74
Q

Which transport ions faster, channels or carriers?

A

channels

75
Q

Ions pass through channels based on:

A

size and charge

76
Q

T or F? Some channels are very selective while allowing a LOT of that specific molecule to pass

A

T

77
Q

T or F? Specificity of channels for ions with the same charge is absolutely specific.

A

F. ranges from highly specific to relatively non specific

78
Q

T or F? Cation and anion channels are absolutely specific for charge.

A

T

79
Q

T or F? Ligand-gated channels are voltage-sensitive

A

F

80
Q

How many times do voltage gated channels span the bilayer?

A

6-transmembrane

81
Q

How many domains does a Na channel have?

A

4

82
Q

What type of segments does a Na channel have?

A

6TM

83
Q

T or F? The tranmembrane segments of the channels are always helices.

A

F. usually

84
Q

Which of the 6 segments has a charge on it for voltage sensitive channels?

A

4th

85
Q

Do the voltage sensitive channels open when the voltage changes inside or outside the cell.

A

inside (only?)

86
Q

Which segement of the channel can move in the membrane and create a pore in the membrane?

A

5th and 6th

87
Q

When in the channel is the p loop found?

A

bw the S5 and S6

88
Q

T or F? the p loop is a protein

A

T

89
Q

Which segments form the gate for the channel?

A

S5 and S6

90
Q

This type of channel has one 6-TM peptide:

A

K channel

91
Q

How many subunits combine to form the K channel?

A

4

92
Q

What structure determines what ions can pass through the channel?

A

p loop (a protein)

93
Q

Examples of 6-transmembrane channels:

A

K+, HCN, cyclic nucleotide (CNG), PKD, TRP, voltage gated Na and Ca channels, polycystic kidney disease (?)

94
Q

HCN channels are regulated by:

A

cAMP

95
Q

CNG channels are regulated by:

A

cGMP or cAMP

96
Q

How many segments are require to form the CNG channels?

A

4, 6-transmembrane proteins

97
Q

What are CNG channels involve in?

A

vision and olfaction

98
Q

What are TRP channels sensitive to?

A

pH, temp, menthol, capsaicin (hot pepper), sweet bitter and umami taste buds, etc.

99
Q

Channels both start and end on the (intra/extra) cellular side of the cell

A

intra

100
Q

What does ENaC stand for?

A

epithelial Na Channel

101
Q

How many subunits is ENaC made of and name?

A

3 (alpha, beta, gamma)

102
Q

How many transmembrane segments does each subunit of the ENaC have?

A

2 and a large extracellular loop

103
Q

What is required for the ENaC to open?

A

nothing. constitutively open

104
Q

What is ENaC involved in?

A

salt taste in tongue and salt excretion in kidney

105
Q

2 types of ligand receptors:

A

Ionotropic and Metabotropic

106
Q

This type of ligand activated receptor binds the ligand and rapidly activates channel:

A

Ionotropic

107
Q

This type of ligand activated receptor binds the ligand and slowly activates channel:

A

Metabotropic

108
Q

The channel is part of the receptor in this type of ligand activated receptor:

A

ionotropic receptor

109
Q

2 excitatory ligands:

A

glutamate and AcH

110
Q

2 inhibitory ligands:

A

GABA and Glycine

111
Q

What affect does AcH have on the heart?

A

slows heart

112
Q

What type of receptor does AcH use?

A

G-protein receptor

113
Q

These are G-protein coupled receptors:

A

metabotropic

114
Q

The G-protein may lead indirectly to:

A

channel activation or modulation

115
Q

enhance or suppress channel activity:

A

modulation

116
Q

most modulators are:

A

neurotransmitters

117
Q

What type of channel is the AcH receptor?

A

ligand-gated channel

118
Q

What subunits is the AcH receptor made of?

A

2 alpha, 1 beta, 1 delta (check)

119
Q

This is a ligand-gated receptor family

A

Ionotropic AcH, GABA, and Glycine receptors

120
Q

How many subunits are the Ionotropic AcH, GABA, and Glycine receptors made of?

A

5 subunits

121
Q

How many times do the Ionotropic AcH, GABA, and Glycine receptors cross the membrane?

A

4 times

122
Q

What forms the pore of the Ionotropic AcH, GABA, and Glycine receptor?

A

M2

123
Q

How many times does each subunit of the inotropic glutamate receptor cross the membrane?

A

3 times, 2nd loop comes back and doesn’t cross all the way

124
Q

How many subunits form the inotropic glutamate receptor?

A

4

125
Q

3 different types of Glutamate Receptors:

A

AMPA, NMDA, Kainate

126
Q

how many channels does the GPCR form?

A

zero

127
Q

How many transmembrane proteins does the GPCR have?

A

7

128
Q

How is the GPCR activated?

A

ligand activated

129
Q

What does the GPCR activate inside the cell?

A

G-protein

130
Q

What does the GPCR start?

A

2nd messenger cascade

131
Q

This type of receptor often regulates a channel:

A

GPCR

132
Q

T or F? The GPCR amplifies response to a stimulus.

A

T

133
Q

How many subunits is the GPCR made of?

A

3

134
Q

The binding of one ligand to a GPCR can lead to the release of _____ of molecules on the other side of the membrane.

A

1000’s

135
Q

T or F? ATP is required for stimulation of the GPCR.

A

F. GTP

136
Q

Examples of GPCR’s:

A

sweet taste receptors, bitter taste receptors, umami taste receptors, neurotransmitter receptors

137
Q

These receptors are involved in autoreceptro feedback:

A

ionotropic and metabotropic receptors

138
Q

What affect will glutamate have on a metabotropic receptor?

A

suppression of voltage-gated calcium channels, negative feedback that controls transmitter release

139
Q

What affect will glutamate have on a ionotropic receptor?

A

depolarize synaptic cell

Physiology (55 decks)

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