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Physiology > Cell Membrane, Membrane Transport and Membrane Potential > Flashcards

Cell Membrane, Membrane Transport and Membrane Potential Flashcards

1
Q

Overall functions of the plasma membrane

A

Separate cytoplasm from ECF, regulate the exchange, communicate with other cells, provide structural attachments between cells or between cell and ECF matrix

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2
Q

Why is it important for the cells to be in communication with each other

A

to have coordinated function

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3
Q

Overall structure of the plasma membrane

A
  • Fluid Mosaic Model
  • Made of up: phospholipids, steroids, proteins, and carbohydrates
  • At body temperature is fluid
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4
Q

Phospholipids structure and function

A

Has polar hydrophilic heads and nonpolar hydrophobic tails

Functions to create a barrier

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5
Q

Permeable compounds in a pure phospholipid bilayer:

A
  • hydrophobic substances- small, nonpolar molecules
  • lipophilic substances
  • water
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6
Q

Non-permeable compounds in a pure phospholipid bilayer:

A
  • large molecules
  • polar molecules
  • charged substances (glucose, ions, amino acids, and proteins) ((These will all be repelled at the fatty acid center so will not pass))
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7
Q

What is cholesterol?

A

helps keep the membrane fluid over a wide range of temperatures and to make membrane water tight

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8
Q

What is the relationship between shape and function of proteins?

A

Shape determines function. Specific shape, specific function. If it alters protein shape it will also alter the function.

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9
Q

Mutations occur in what protein level

A

primary structure, random chance event in an exon changes the amino acid sequence

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10
Q

pH, Temp, Osm occur in what protein level?

A

loss of secondary, tertiary, and quaternary structure through denaturation

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11
Q

Covalent and allosteric modulation changes occur in which protein level?

A

change in secondary, tertiary, and quaternary structure in turning the protein on or off.

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12
Q

What happens when there is a denaturation occuring?

A

This is a permanent change that alters the protein function by having a protein shape change

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13
Q

What are the functional classifications of proteins?

A
  1. Receptors
  2. Transport proteins
  3. Structural proteins
  4. Enzymes
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14
Q

What are the properties of receptors?

A
  1. Specificity
  2. Saturation
  3. Competition
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15
Q

How are proteins specific?

A

each type of protein, in general, will interact with only one type of substance or class of substances

**Specificity gives the cell great control

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16
Q

How does saturation work with proteins?

A

There are a set number of proteins and therefore a set number of binding sites.
It is dependent on the [protein] and the [substance]. If wanted to increase saturation level we would need more receptors.

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17
Q

How does competition work?

A

A exogenous ligand will block endogenous ligands. This causes for no effect to be produced.

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18
Q

How can cells respond to receptor activation? (theres 3)

A
  • need receptor, if no receptor, no response
  • two different ligands binding to the same receptor can give the same response
  • one ligand can bind to two receptors and give two different responses
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19
Q

receptor affinity is proportionately or inversely proportionately related to ligands bound to receptors

A

proportionately

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20
Q

receptor affinity is proportionately or inversely proportionately related to Kd?

A

inversely proportionately

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21
Q

What are the three types of transport proteins?

A
  1. channels
  2. carriers
  3. active transporters
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22
Q

What are channels?

A

they are 3D proteins that forms a fluid filled pore, connects ECF and cytoplasm

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23
Q

Energy input needed for channels?

A

None, they are passive. Ions go into and out of cell through facilitated diffusion

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24
Q

What are leak currents?

A

a charge is flowing across the membrane, even at rest there is a measure change.

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25
Q

What are the two modulations to change a protein shape?

A

Allosteric modulation and covalent modulation

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26
Q

Na+ is higher in the ICF or ECF?

A

ECF

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27
Q

K+ is higher in the ICF or ECF?

A

ICF

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28
Q

Ca++ is higher in the ICF or ECF?

A

ECF

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29
Q

Mg++ is higher in the ICF or ECF?

A

ICF

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30
Q

Cl- is higher in the ICF or ECF?

A

ECF

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31
Q

HCO3- is higher in the ICF or ECF?

A

ECF

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32
Q

Phosphates is higher in the ICF or ECF?

A

ICF

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33
Q

Glucose is higher in the ICF or ECF?

A

ECF

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34
Q

Amino acids is higher in the ICF or ECF?

A

ICF

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35
Q

H+ is higher in the ICF or ECF?

A

ICF (pH is 7 vs ECF pH is 7.4)

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36
Q

Proteins is higher in the ICF or ECF?

A

ICF

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37
Q

How does passive transport travel gradients

A

down the gradient (hi to lo)

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38
Q

What are the types of passive transport?

A
  1. Diffusion
  2. Osmosis
  3. Bulk Flow
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39
Q

How does active transport travel gradients?

A

travels up the gradients (lo to hi)

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40
Q

Passive transport rate of movement is directly and indirectly correlated with?

A
  1. directly with temperature, as temperature increases so does the passive rate of movement
  2. indirectly with mass of the molecule, as the mass of the molecule decreases the rate of passive transport increases
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41
Q

What is the goal of passive transport?

A

to move the system towards equilibrium

42
Q

what is the driving force for the mass and heat flow model of diffusion

A

The concentration gradient is the driving force.

If you increase the gradient you increase the driving force

43
Q

when determining which line of net flux has the higher permeability what do you look for

A

the slope of the line, the bigger the slope the higher the flux, and the greater the permeability and lower resistance (see graph picture for reference)

44
Q

What are the types of diffusion?

A

simple and facilitated diffusion

45
Q

what are simple diffusion substances?

A

hydrophobic/lipophilic substances

46
Q

what are facilitated diffusion substances?

A

hydrophilic/lipophobic substances

47
Q

what does simple diffusion need to get through a membrane?

A

nothing, it just moves directly through a phospholipid bilayer

48
Q

what is the SDR

A

=simple diffusion rate

SDR∝ (deltaG)(T)(A)/(R)(D)

49
Q

what is the FDR

A

= facilitated diffusion rate

FDRions ∝ (deltaG)(T)(#channels)(Popen)

Popen= probability of channels being open

FDRmolecules ∝ (deltaG)(T)(#carriers)

50
Q

what does facilitated diffusion need to get through a membrane?

A

it requires membrane channels or carriers, needs a plasma membrane

51
Q

is simple diffusion regulated? and why

A

no, unregulated because it will move through the cell regardless of the substance being good or bad

ex: lipophilic- alcohol. Its a toxin but it will still diffuse and cause harm

52
Q

is facilitated diffusion regulated? and why

A

yes, it is regulated through specificity saturation and competition

53
Q

how are the kinetics different between facilitated and simple diffusion

A

facilitated has carrier proteins so it can only have a fixed amount of ligands. On a graph it will be sloped and reach a max. Simple diffusion is not saturable.

54
Q

what is osmosis facilitated by

A

aquaporins

55
Q

which way will water molecules move

A

move passively down free water gradient (towards the area with a higher solute concentration)

56
Q

what three things can change the osmotic equilibrium

A
  1. solute concentration
  2. water concentration
  3. container volume
57
Q

if the osmotic equilibrium changes does the volume equilibrium change too?

A

no, only the osmotic equilibrium will change with solute concentration, water concentration, container volume

58
Q

what can determine water movement via osmosis?

A

ONLY impermeable substances

59
Q

isosmotic

A

bathing solution Osm = cytosolic Osm

60
Q

hyposmotic

A

bathing solution Osm < cytosolic Osm

61
Q

hyperosmotic

A

bathing solution Osm > cytosolic Osm

62
Q

tonicity

A

impermeable substances ONLY, determines the direction of water via osmosis

63
Q

isotonic

A

concentration of impermeable solute = cell solute. No net volume change.

64
Q

hypotonic

A

concentration of impermeable solute < cell solute. Cell will swell.

65
Q

hypertonic

A

concentration of impermeable solute > cell solute. Cell will shrink.

66
Q

in normal circumstances, what is ECF Osm to the cell cytosol?

A

isotonic

67
Q

what is osmotic pressure?

A

the pressure required to STOP the flow of water into a compartment

68
Q

what are systematic permeable solutes?

A

ethanol, FA, O2, CO2, steroids, urea and glucose

*urea and glucose over time are permeable to cells, at any give moment it may or may not be permeable to urea or glucose.

69
Q

what are some impermeable solutes?

A

Na+, K+, Cl-. HCO3-, Protein, any charges or ions

70
Q

what is something that is always permeable to urea and glucose

A

RBC

71
Q

the volume and osmolarity relationship of water in ICF and ECF:

A

Volume of water in ICF and ECF are UNEQUAL

Osmolarity of ECF and ICF are EQUAL

72
Q

what are active transporters?

A
  • transmembrane protein that moves ions and hydrophilic across the plasma membrane UP a concentration gradient
  • requires energy
73
Q

what is a uniporter?

A

an active transporter that moves only one substance

74
Q

what is a symporter/cotransporter?

A

an active transporter that moves substances in the same direction

75
Q

what is an antiporter/countertranporter?

A

an active transporter that moves substances in different directions

76
Q

what are primary active transporters

A

the transporters get their energy directly from the breakdown of ATP
aka ATPase pumps

77
Q

what are secondary active transporters

A

transporters that energy released from one substance moving down a gradient is used to pump a second substance up a gradient

aka Cotransporters (symporters) or countertransporters (antiporters)

78
Q

functions of Na+/K+ pump

A
  • maintain Na+ and K+ concentration differences

- electrogenic (establishes negative membrane potential)

79
Q

how does the Na+/glucose symporter work?

A

it uses energy to up the gradient. It is supplied by the Na+ moving down the gradient to move the glucose

80
Q

what are the two types of vesicular/bulk transport?

A

Endocytosis and Exocytosis

81
Q

how does bulk transport impact the plasma membrane?

A

endocytosis and exocytosis is how the cell modifies composition of the plasma membrane

82
Q

what is the difference between the components of plasma and interstitial fluid?

A

plasma has PROTEIN

both have A lot of (hi) Na+, then Cl-, then HCO3-, and K+ (lo)

83
Q

what makes up the components of ICF

A

(hi) K+, misc. phosphates, Protein, Na+/Cl-/HCO3-

84
Q

what is membrane potential and what does it regulate?

A

the charge difference across the plasma membrane

it regulates exocytosis, channels open or close, or movement of ions in/out of cell

85
Q

what is the resting membrane?

A

the charge difference between across the plasma membrane when the cell is at rest

86
Q

what is the normal resting Vm?

A

=-70mV, this can vary by cell type

87
Q

what are the two gradients that make up the membrane potential?

A

electrochemical gradient and concentration gradient

88
Q

what determines the strength of the electrical gradient?

A

on the valence of the ion and the magnitude of the membrane potential

(aka the charge and the Vm of the cell)

89
Q

what does Eion stand for? and what does it mean?

A

the equilibrium potential

no net movement of ions through channels via facilitated diffusion

90
Q

what is the Nernst equation?

A

Eion(mV)= 61/Zlog([ion]ECF/[ion]ICF)

91
Q

the impact of changing Vm onto the FDR

A

when you change Vm it will change the electrochemical gradient and it will change the facilitated rate of diffusion

92
Q

what does depolarization mean?

A

Vm becomes less negative than rest

93
Q

what does repolarization mean?

A

Vm change that restores resting Vm

94
Q

what does hyperpolarization mean?

A

Vm becomes more negative than rest

95
Q

what does repolarization mean?

A

Vm change that restores resting Vm

96
Q

how does Vm affect ion permeability?

A

ion moves down EC gradient, Vm moves towards Eion, decreases rate of ion movement via facilitated diffusion.

97
Q

what helps maintain resting membrane potential?

A

a K+ leaky channel. K+ is a determinant of resting membrane potential

98
Q

What are the determinants of resting membrane potential?

A
  • relative ion permeabilities

- Na+/K+ ATPase activity

99
Q

how to change membrane potential

A
  1. change the membranes permeability to an ion (open/close a channel, or change activity of an active transporter)
  2. Change the ion concentration gradient across the membrane
100
Q

what is hyperkalemia?

A

increased blood K+ [ ] brings the membrane closer to threshold.

101
Q

what is hypokalemia?

A

decreased blood K+ [ ], it brings the membrane further away from threshold, harder to fire a stimulus.

Physiology (6 decks)

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