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Physiology > Student Introduction 2 Cell Membrane, Membrane Transport, and Membrane Potential > Flashcards

Student Introduction 2 Cell Membrane, Membrane Transport, and Membrane Potential Flashcards

1
Q

what are the functions of the plasma membrane

A

-separate cytoplasm from ECF
-regulate exchange between ECF and cytoplasm
-communicate with other cells
-provide structural attachments between cells or between cell and ECM

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2
Q

what are the 4 molecules that make up the plasma membrane

A

-phospholipids
-steroids
- proteins
-carbohydrates

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3
Q

what is the plasma membrane permeable to and non permeable to

A

-Permeable: hydrophobic substances- small nonpolar molecules such as gases, fatty acids, steroids, lipophilic substances like ethanol and water
-Nonpermeable: larger molecules, polar molecules, charged substances such as glucose, ions, amino acids, and proteins

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4
Q

what are the 2 functions of cholesterol

A
  • keep membrane fluid over a wide range of temperatures
    -make membrane water tight
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5
Q

what part of proteins do mutations alter

A

primary structure

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6
Q

what part of proteins does pH, T, Osm alter

A

loss of secondary, tertiary, quarternary structure-denaturation

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7
Q

what part of proteins does covalent/allosteric modulation alter

A

secondary, tertiary, and quarternary structure

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8
Q

what are the 3 structural classifications of proteins

A

-transmembrane
-integral
-peripheral

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9
Q

what do receptors do

A

bind to specific chemical signals called ligands and transmit that information to the cytoplasm

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10
Q

what are the properties of receptora

A

-specificity
-saturation
-competition

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11
Q

define specificity

A

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

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12
Q

what is saturation

A

the fraction of total binding sites that are occupied at any given time

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13
Q

what is saturation dependent on

A

the concentration of protein and concentration of substances

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14
Q

what is the relationship between transport rate and substrate concentration

A

they are proportional until the carriers are saturated

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15
Q

what is a competitive inhibitor

A

a chemical substance (exogenous ligand) that binds to the active site of the protein and blocks the endogenous ligand from binding

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16
Q

what happens when a competitor binds to a receptor

A

does not produce an effect

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17
Q

what is the level of inhibition dependent on

A

the concentration of protein, concentration of endogenous ligand and concentration of competitive inhibitor

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18
Q

what does an agonist do

A

activate the receptor

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19
Q

what does an antagonist do

A

block receptor activity

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20
Q

what mediates the response of a cell to a chemical signal

A

receptor mediated

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21
Q

what is the relationship between affinity and number of ligands bound to receptors at any given time

A

-proportionate
high affinity = high number of ligands bound to receptors

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22
Q

what is the relationship between affinity and Kd

A

inversely proportionate

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23
Q

what do transport proteins do

A

move hydrophilic substances across the plasma membrane of cell

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24
Q

what are the 3 types of transport proteins

A

channels, carriers, active transporters

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25
Q

what are channels

A

transmembrane proteins with a 3D shape that forms a tiny fluid filled pore connecting ECF and cytoplasm

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26
Q

what is the function of channels and do they require energy

A

facilitated diffusion of ions into and out of the cell, passive

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27
Q

are channels specific

A

can be somewhat specific

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28
Q

what are the types of channels

A

open, gated

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29
Q

how do open channels work and what do they create

A

always open and ions freely flow through via facilitated diffusion
-creates leak currents

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30
Q

what are the 3 types of gated channels

A

-chemically gated
-mechanically gated
-voltage gated

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31
Q

what type of binding occurs in allosteric modulation

A

non-covalent

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32
Q

what part of proteins change in allosteric modulation

A

secondary, tertiary, and quarternary

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33
Q

what happens in allosteric modulation

A

chemical substance binds to protein away from active site

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34
Q

what happens in covalent modulation

A

a kinase opens the channel and a phosphatase closes the channel

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35
Q

which type of modulation needs a cataylst to bind: allosteric or covalent

A

covalent modulators

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36
Q

what are carriers and do they require energy

A

transmembrane protein that moves hydrophilic building blocks across the plasma membrane via facilitated diffusion
-passive

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37
Q

what are the properties of carrier

A

specificity, saturation and competition

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38
Q

what are active transporters

A

transmembrane protein that moves ions and hydrophilic building blocks across the plasma membrane via active transport

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39
Q

what are the properties of active transporters

A

specificity, saturation, and competition

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40
Q

what do structural proteins do

A

forms cell to cell attachments that hold adjacent epithelial cells together

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41
Q

what do tight junctions do

A

prevents intercellular movement of fluid and dissolved substances

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42
Q

what do desmosomes do

A

structural support

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43
Q

what do gap junctions do

A

cell to cell communication via ions

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44
Q

what type of cell to cell junctions prevent fluid flow

A

tight junctions

45
Q

what are enzymes and what do they do

A

integral membrane, transmembrane, or peripheral membrane proteins that catalyze specific chemical reactions either on the extracellular surface of cell or inside cell

46
Q

what are the properties of enzymes

A

specificity, saturation, and competition

47
Q

what is the mass action model

A

protein with binding site plus specific substance -> <- protein/substance

48
Q

where do carbohydrates attach

A

to the EC surface of membrane lipids and proteins- the glycocalyx

49
Q

what does the glycocalyx do

A

plays important role in enabling cells to identify and interact with each other

50
Q

Are the following concentrations higher inside or outside of the cell: Na+,K+,Ca++, Mg++, Cl-, HCO3-, phosphates, glucose, amino acids, pH, proteins

A

Na+: outside
K+: inside
Ca++: outside
Mg++: inside
Cl-: outside
HCO3-: outside
phosphates: inside
glucose: outside
amino acids: inside
pH: inside
proteins: inside

51
Q

what are the types of passive transport

A

diffusion, osmosis, bulk flow

52
Q

what are the types of active transport

A

active transporters and bulk (vesicular) transport

53
Q

what is random thermal motion

A

molecules in a fluid are continuously and randomly bouncing around

54
Q

what is the equation for the rate of movement in passive tranport

A

Temperature/ Mass

55
Q

how fast do water and glucose move at body temperature

A

water at 1,200 mph and glucose moves at 500 mph

56
Q

what is diffusion

A

movement of substances other than water down a gradient

57
Q

what can the mass and heat flow model be used to describe

A

diffusion, osmosis, blood flow through blood vessels, air flow through airways, capillary exchange

58
Q

what substances move by simple diffusion? facilitated?

A

simple: hydrophobic/lipophilic
facilitated: hydrophilic/lipophobic

59
Q

how do substances move in simple diffusion? facilitated?

A

simple: moves directly through phospholipid bilayer
facilitated: requires membrane channels or carriers

60
Q

which process is faster, simple diffusion or facilitated diffusion?

A

facilitated diffusion

61
Q

which type of diffusion is regulated and what regulates it

A

facilitated diffusion regulated by specificity, saturation and competition

62
Q

which type of diffusion requires a plasma membrane

A

facilitated diffusion

63
Q

what is the formula for simple diffusion rate

A

(change in gradient)(temperature)(surface area) / (resistance)(diffusion distance)

64
Q

what is resistance affected by

A

viscosity of fluid and size of molecule

65
Q

what are the formulas for facilitated diffusion rate

A

(change in gradient)(temperature)(number of channels)(probability that channels are open)
AND
(change in gradient)(temperature)(number of carriers)

66
Q

what facilitated diffusion rate equation do you use when talking about ions vs molecules

A

ions use the equation with channels and molecules use the equation with carriers

67
Q

what are examples of substances that will move by simple diffusion?facilitated diffusion?

A

simple: O2, CO2, ethanol, steroids
facilitated: glucose, amino acids, all ions, urea

68
Q

why are the kinetics between simple diffusion and facilitated diffusion different

A

because facilitated diffusion reaches saturation

69
Q

what is osmolarity

A

the total free solute concentration of a solution is known as its osmolarity

70
Q

what types of solute does osmolarity depend on

A

permeable and impermeable

71
Q

what is the relationship between osmol and mol

A

one osmol is equal to 1 mol of solute particles

72
Q

what is isosmotic

A

bathing solution Osm = cytosolic Osm

73
Q

what is hyposmotic

A

bathing solution Osm< cytosolic Osm

74
Q

what is hyperosmotic

A

bathing solution Osm> cytosolic Osm

75
Q

what is tonicity defined by

A

the number of impermeable substances only

76
Q

what does tonicity determine

A

the direction of H2O movement via osmosis

77
Q

what is an isotonic solution

A

concentration of impermeable solute - cell cytosol

78
Q

what is a hypotonic solution and what is the volume change in the cell

A

-concentration of impermeable solute < cell cytosol
cells gain water and swell

79
Q

what is a hypertonic solution and what is the volume change in the cell

A

concentration of impermeable solute > cell cytosol
cells will lose water and shrink

80
Q

what is the normal ECF osmolarity of nonpenetrating solute

A

300 mOsm

81
Q

what is the normal cytosol of nonpenetrating solute

A

300 mOsm

82
Q

what is the osmolarity under normal circumstances

A

ECF osm is isotonic to cell cytosol

83
Q

what substances are permeable

A

ethanol, fatty acids, O2, CO2, steroids, urea, glucose

84
Q

what substances are impermeable

A

Na+, K+, Cl-, HCO3-, protein

85
Q

what does cell permeability to urea and glucose depend on

A

cell type - RBC are always permeable
chemical signals

86
Q

what portion of water is in intracellular fluid, and ECF

A

40% in ICF and 20% ECF

87
Q

is the volume of water in the intracellular vs extracellular spaces equal? what about osmolarity?

A

volume water is unequal
osmolarity is equal

88
Q

what is the classification of active tranporters based on

A

-number of substances being transported
-directions substances are transported
-source of energy for transport

89
Q

what does a uniporter do

A

moves only one substance

90
Q

what do symporters do

A

all substances moving in the same direction

91
Q

what do antiporters do

A

substances moving in different directions

92
Q

where does energy come from in primary active transport

A

directly from the breakdown of ATP

93
Q

where does energy come from in secondary active transport

A

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

94
Q

what does electrogenic mean

A

establishes negative membrane potential

95
Q

what is an example of a primary active transport pump

A

sodium potassium pump

96
Q

what is an example of a cotransporter

A

sodium glucose symporter

97
Q

is vesicular transport gradient dependent

A

no

98
Q

what are the two types of vesicular transport

A

endocytosis and exocytosis

99
Q

what does endocytosis do

A
  • brings substances into cell
    -forms vesicle
  • removes membrane from plasma membrane
100
Q

what does exocytosis do

A

removes substances from cell
- vesicle fuses to membrane
- adds membrane to plasma membrane

101
Q

how does the cell modify composition of plasma membrane

A

endocytosis and exocytosis

102
Q

what are the three forms of endocytosis

A

-pinocytosis
- phagocytosis
- receptor mediated endocytosis

103
Q

what happens in pinocytosis and what cells perform this

A

nonspecific substances brought into the cell
-all cells all the time

104
Q

what happens in phagocytosis and what cells perform this

A

foreign substances brought into the cell
- phagocytes only

105
Q

what happens in receptor mediated endocytosis and what cells perform this

A

specific substances brought into the cell
-all cells all the time

106
Q

what is the membrane potential created by

A

unequal distribution of anions and cations across the cell membrane

107
Q

what is charge separation equal to

A

source of energy

108
Q

what is the normal resting membrane potential

A

-70mV

Physiology (41 decks)

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