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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
what are channels
transmembrane proteins with a 3D shape that forms a tiny fluid filled pore connecting ECF and cytoplasm
26
what is the function of channels and do they require energy
facilitated diffusion of ions into and out of the cell, passive
27
are channels specific
can be somewhat specific
28
what are the types of channels
open, gated
29
how do open channels work and what do they create
always open and ions freely flow through via facilitated diffusion -creates leak currents
30
what are the 3 types of gated channels
-chemically gated -mechanically gated -voltage gated
31
what type of binding occurs in allosteric modulation
non-covalent
32
what part of proteins change in allosteric modulation
secondary, tertiary, and quarternary
33
what happens in allosteric modulation
chemical substance binds to protein away from active site
34
what happens in covalent modulation
a kinase opens the channel and a phosphatase closes the channel
35
which type of modulation needs a cataylst to bind: allosteric or covalent
covalent modulators
36
what are carriers and do they require energy
transmembrane protein that moves hydrophilic building blocks across the plasma membrane via facilitated diffusion -passive
37
what are the properties of carrier
specificity, saturation and competition
38
what are active transporters
transmembrane protein that moves ions and hydrophilic building blocks across the plasma membrane via active transport
39
what are the properties of active transporters
specificity, saturation, and competition
40
what do structural proteins do
forms cell to cell attachments that hold adjacent epithelial cells together
41
what do tight junctions do
prevents intercellular movement of fluid and dissolved substances
42
what do desmosomes do
structural support
43
what do gap junctions do
cell to cell communication via ions
44
what type of cell to cell junctions prevent fluid flow
tight junctions
45
what are enzymes and what do they do
integral membrane, transmembrane, or peripheral membrane proteins that catalyze specific chemical reactions either on the extracellular surface of cell or inside cell
46
what are the properties of enzymes
specificity, saturation, and competition
47
what is the mass action model
protein with binding site plus specific substance -> <- protein/substance
48
where do carbohydrates attach
to the EC surface of membrane lipids and proteins- the glycocalyx
49
what does the glycocalyx do
plays important role in enabling cells to identify and interact with each other
50
Are the following concentrations higher inside or outside of the cell: Na+,K+,Ca++, Mg++, Cl-, HCO3-, phosphates, glucose, amino acids, pH, proteins
Na+: outside K+: inside Ca++: outside Mg++: inside Cl-: outside HCO3-: outside phosphates: inside glucose: outside amino acids: inside pH: inside proteins: inside
51
what are the types of passive transport
diffusion, osmosis, bulk flow
52
what are the types of active transport
active transporters and bulk (vesicular) transport
53
what is random thermal motion
molecules in a fluid are continuously and randomly bouncing around
54
what is the equation for the rate of movement in passive tranport
Temperature/ Mass
55
how fast do water and glucose move at body temperature
water at 1,200 mph and glucose moves at 500 mph
56
what is diffusion
movement of substances other than water down a gradient
57
what can the mass and heat flow model be used to describe
diffusion, osmosis, blood flow through blood vessels, air flow through airways, capillary exchange
58
what substances move by simple diffusion? facilitated?
simple: hydrophobic/lipophilic facilitated: hydrophilic/lipophobic
59
how do substances move in simple diffusion? facilitated?
simple: moves directly through phospholipid bilayer facilitated: requires membrane channels or carriers
60
which process is faster, simple diffusion or facilitated diffusion?
facilitated diffusion
61
which type of diffusion is regulated and what regulates it
facilitated diffusion regulated by specificity, saturation and competition
62
which type of diffusion requires a plasma membrane
facilitated diffusion
63
what is the formula for simple diffusion rate
(change in gradient)(temperature)(surface area) / (resistance)(diffusion distance)
64
what is resistance affected by
viscosity of fluid and size of molecule
65
what are the formulas for facilitated diffusion rate
(change in gradient)(temperature)(number of channels)(probability that channels are open) AND (change in gradient)(temperature)(number of carriers)
66
what facilitated diffusion rate equation do you use when talking about ions vs molecules
ions use the equation with channels and molecules use the equation with carriers
67
what are examples of substances that will move by simple diffusion?facilitated diffusion?
simple: O2, CO2, ethanol, steroids facilitated: glucose, amino acids, all ions, urea
68
why are the kinetics between simple diffusion and facilitated diffusion different
because facilitated diffusion reaches saturation
69
what is osmolarity
the total free solute concentration of a solution is known as its osmolarity
70
what types of solute does osmolarity depend on
permeable and impermeable
71
what is the relationship between osmol and mol
one osmol is equal to 1 mol of solute particles
72
what is isosmotic
bathing solution Osm = cytosolic Osm
73
what is hyposmotic
bathing solution Osm< cytosolic Osm
74
what is hyperosmotic
bathing solution Osm> cytosolic Osm
75
what is tonicity defined by
the number of impermeable substances only
76
what does tonicity determine
the direction of H2O movement via osmosis
77
what is an isotonic solution
concentration of impermeable solute - cell cytosol
78
what is a hypotonic solution and what is the volume change in the cell
-concentration of impermeable solute < cell cytosol cells gain water and swell
79
what is a hypertonic solution and what is the volume change in the cell
concentration of impermeable solute > cell cytosol cells will lose water and shrink
80
what is the normal ECF osmolarity of nonpenetrating solute
300 mOsm
81
what is the normal cytosol of nonpenetrating solute
300 mOsm
82
what is the osmolarity under normal circumstances
ECF osm is isotonic to cell cytosol
83
what substances are permeable
ethanol, fatty acids, O2, CO2, steroids, urea, glucose
84
what substances are impermeable
Na+, K+, Cl-, HCO3-, protein
85
what does cell permeability to urea and glucose depend on
cell type - RBC are always permeable chemical signals
86
what portion of water is in intracellular fluid, and ECF
40% in ICF and 20% ECF
87
is the volume of water in the intracellular vs extracellular spaces equal? what about osmolarity?
volume water is unequal osmolarity is equal
88
what is the classification of active tranporters based on
-number of substances being transported -directions substances are transported -source of energy for transport
89
what does a uniporter do
moves only one substance
90
what do symporters do
all substances moving in the same direction
91
what do antiporters do
substances moving in different directions
92
where does energy come from in primary active transport
directly from the breakdown of ATP
93
where does energy come from in secondary active transport
energy released from one substance moving down a gradient is used to pump a second substance up a gradient
94
what does electrogenic mean
establishes negative membrane potential
95
what is an example of a primary active transport pump
sodium potassium pump
96
what is an example of a cotransporter
sodium glucose symporter
97
is vesicular transport gradient dependent
no
98
what are the two types of vesicular transport
endocytosis and exocytosis
99
what does endocytosis do
- brings substances into cell -forms vesicle - removes membrane from plasma membrane
100
what does exocytosis do
removes substances from cell - vesicle fuses to membrane - adds membrane to plasma membrane
101
how does the cell modify composition of plasma membrane
endocytosis and exocytosis
102
what are the three forms of endocytosis
-pinocytosis - phagocytosis - receptor mediated endocytosis
103
what happens in pinocytosis and what cells perform this
nonspecific substances brought into the cell -all cells all the time
104
what happens in phagocytosis and what cells perform this
foreign substances brought into the cell - phagocytes only
105
what happens in receptor mediated endocytosis and what cells perform this
specific substances brought into the cell -all cells all the time
106
what is the membrane potential created by
unequal distribution of anions and cations across the cell membrane
107
what is charge separation equal to
source of energy
108
what is the normal resting membrane potential
-70mV

Physiology (41 decks)

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