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Human Physiology > Equilibrium Potentials And Resting Mem & Graded Potentials > Flashcards

Equilibrium Potentials And Resting Mem & Graded Potentials Flashcards

1
Q

Nernst equation:

A

(+60 or -60)/zk (log [concentration out}/ [concenetration in]

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2
Q

Nernst equation: The concentrations of K+ inside and outside the cell account for the

A

chemical/concentration gradient

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3
Q

Nernst equation: zk that represents the

A

valence electrons accounts for the electrical driving forces

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4
Q

is reached when the movement of ions down their electrical gradient is equal and opposite in the direction to the movement of ions down their concentration (chemical) gradient

A

Electrochemical equilibrium

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5
Q

is the membrane potential in a cell when electrochemical equilibrium is reached

A

Equilibrium potentials

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6
Q

Equilibrium potentials for K+, Na+, Ca2+

A

K+= -89 mV
Na+= +60 mV
Ca2+= +134 mV

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7
Q

Differences in equilibrium potential for Na+, Ca2+, and K+

A

Na+ makes the cell inside slightly less negative, smaller gradient for Na+, less magnitude

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8
Q

What change has a larger effect: A 5 mM increase in the ECF of K+ vs. a 5mM increase in ECF of Na+

A

K+: because it has a greater effect from 5 to 10, then 150 to 155.

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9
Q

When you increase the ECF of K+, and the ICF remains the same, what is the effect of this?

A

It decreases the size of the concentration gradient more than Na+ concentration gradient.

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10
Q

In order for the cell to have a negative resting membrane potential it needs…

A

More K+ leak channels, allowing more movement of K+ down the gradient AND Na/K ATPase protein to maintain the gradient

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11
Q

Explain why the resting membrane potential is closer to EK than to ENa

A

more K leak channels (permeability) are open, therefore net movement of K down its concentration gradient out of the cell—leading to negative membrane potential

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12
Q

two reasons why changes in extracellular K + concentration have more dramatic effects on resting membrane potential than do changes in extracellular Na+ concentration

A
  • charge difference of K+ flowing out and Na+ flowing in.
  • larger K+ gradient
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13
Q

what the relative ion permeability (P) represents in the Goldman-Hodgkin-Katz equation

A

the ion permeability being rapidly variable due to ion channel gating

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14
Q

Explain which variables in this equation are generally quite stable in the Goldman-Hodgkin-Katz equation

A

The ion gradients (concentrations) due to Na+/K+ ATPase protein

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15
Q

What ions have the largest influence over the membrane potential

A

Large concentration gradients and high membrane permeability

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16
Q

K+ makes the membrane potential…

A

slightly more negative (hyperpolarize)

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17
Q

Na+ makes the membrane potential…

A

slightly less negative (depolarize)

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18
Q

Ca2+ makes the membrane potential…

A

slightly less negative (depolarize)

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19
Q

Cl- makes the membrane potential…

A

slightly more negative (hyperpolarize)

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20
Q

Direction of concentration gradients and electrical gradients for Ca2+:

A

Electrical gradient= inward (inside) the cell
Concentration gradient= inside the cell

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21
Q

Direction of concentration gradients and electrical gradients for K+:

A

Electrical gradient= inside the cell
Concentration gradient=outside

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22
Q

Direction of concentration gradients and electrical gradients for Na+:

A

Electrical gradient= inside the cell
Concentration gradient= inside the cell

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23
Q

Direction of concentration gradients and electrical gradients for Cl-:

A

Electrical gradient= outward (outside) the cell
Concentration gradient= inside the cell

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24
Q

Direction of concentration gradients and electrical gradients for Anions:

A

Electrical gradient= outward (outside) the cell
Concentration gradient= outside the cell

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25
Q

TOTAL number of particles per liter of water. The sum of
penetrating and non-penetrating molecules in a solution

A

osmolarity

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26
Q

how to calculate the osmolarity of solutions

A

Molarity (mol/L) x number of particles per molecule dissolved

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27
Q

Particles that ionize or dissociate are known as (ex. NaCl)

A

non-penetrating

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28
Q

does not dissolve or dissociate are known as

A

penetrating (urea, ethanol)

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29
Q

two mechanisms by which water can move across plasma membranes…

A
  1. Through simple diffusion
  2. By moving through aquaporins, integral membrane proteins function as water channels
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30
Q

Typical value of intracellular osmolarity of human cells

A

300 mOSM

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31
Q

able to pass through a membrane

A

penetrating solutes

32
Q

Any solute present in the ECF that cannot effectively pass through a plasma membrane

A

Non-penetrating solutes

33
Q

if two solutions have the same osmolarities (penetrating and nonpenetrating combination)

A

Iso-osmotic

34
Q

the osmolarities of nonpenetrating solutes are the same on the inside and outside of the membrane

A

isotonic

35
Q

Tonicity only depends on

A

non-penetrating

36
Q

A solution with a higher osmolarity (more solute particles) than another solution

A

Hyperosmotic

37
Q

A solution with lower osmolarity (fewer solute particles) than another solution

A

hypo-osmotic

38
Q

Solution has a higher osmolarity of non-penetrating solute outside the cell than inside the cell

A

hypertonic

39
Q

Hypertonic solution results in what H2O movement

A

outward

40
Q

Solution has a lower osmolarity of non-penetrating solutes than inside the cell

A

hypotonic

41
Q

Hyportonic solution results in what H2O movement

A

inward

42
Q

If all solutes in the isosmotic solution are non-penetrating, then the solution is

A

isotonic

43
Q

If RBC’s were placed in an iso-osmotic solution with only penetrating solutes, the penetrating solutes would

A

enter the RBCs on their own, hypotonic

44
Q

If RBC’s were placed in an iso-osmotic solution with only non-penetrating solutes, the solution would be

A

isotonic

45
Q

Predict what would happen to the volume of red blood cells if they were placed in a 1400 mOSM solution of NaCl…

A

The solution would be hypertonic and RBC would shrivel and die because the water moves out of the cell

46
Q

Predict what would happen to the volume of RBCs if they were placed in a solution containing 700 mOSM of NaCl plus 700 mOSM of urea…

A

the RBCs would also shrink but less, because less water was needed to leave the cell

47
Q

Explain how the presence of approximately 150 mM NaCl (saline) can prevent osmotic swelling of red blood cells in a solution that also contains some penetrating solute….

A

150 mM NaCl dissociates into 300 mOsm which is the same concentration inside the cell: solutions are isotonic

48
Q

The higher the osmolarity= the __ the water concentration

A

lower

49
Q

Two solutions with the same osmolarity have the

A

same water concentration

50
Q

Adding solute, __ water concentration

A

decreases

51
Q

As solute concentration increases, water concentration

A

decreases

52
Q

what two events generate graded potentials…

A

a stimulus applied to sensory receptor and neurotransmitter synapse

53
Q

sensory receptors contain what channel

A

transduction

54
Q

characteristics of a stimulus

A

intensity, modality, location in body

55
Q

determines how many channels are open and how long

A

intensity

56
Q

type of stimulus: pain, touch, etc; that activates the receptor

A

modality

57
Q

coding of the stimulus by the

A

size of the receptor potential

58
Q

The larger the stimulus, __ transduction channels open, __ receptor potential

A

more, larger

59
Q

if opening of transduction channels leads to a depolarizing potential, which ions would these channels likely to be permeable?
Only Na+
Only K+
Both, but more permeable to K+ then Na+

A

Na+

60
Q

if opening of transduction channels leads to a hyperpolarizing potential, which ions would these channels likely to be permeable?
Only Na+
Only K+
Both, but more permeable to K+ then Na+

A

K+

61
Q

peripheral endings of sensory neurons

A

Sensory receptors

62
Q

have transduction channels that are opened by a specific type of stimulus (e.g. mechanical, thermal, chemical)

A

Sensory receptors

63
Q

convert a stimulus into an electrical signal we call a graded potential (GP)

A

Sensory receptors

64
Q

conversion of one type of stimulus energy (e.g. pressure) to an electrical signal (i.e. receptor potential)

A

sensory transduction

65
Q

In sensory transduction what channel mediates it

A

gated channel

66
Q

How does a sensory transduction occur? (with Na+ and Ca2+)

A

An influx of sodium and calcium causes a depolarizing receptor potential—stimuli opens channels.

67
Q

How does a pacinian corpuscle work

A

if pushed on, the capsule deforms by a stimulus and the channels open

68
Q

Thermoreceptors

A

have transduction channels that open when temp increases or decreases

69
Q

Nociceptors have transduction channels that open when

A

exposed to extreme heat, intense mechanical stimuli, and chemicals released from cells that have been damaged

70
Q

What channel determines resting membrane potential

A

Leak channels

71
Q

Channel that randomly open and close, so at any given
time

A

leak channels

72
Q

change a physical stimulus into an electrical event (i.e. change in membrane potential)

A

transduction channels

73
Q

Size and duration of the receptor potential is determined by

A

how many transduction channels are opened by the
stimulus, and for how long they stay open

74
Q

The modality of a sensory receptor is determined by

A

Type of transduction channel, structure where channel is located, location of receptor

75
Q

The graded potentials that occur in sensory receptors

A

sensory receptor potential

Human Physiology (14 decks)

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