Item 2 Flashcards
Cellular fluid is measured in _ concentrations
millimolar
mM refers to _, a measurement of cellular fluid
millimolar
Passive transport is a.k.a…
spontaneous transport
Spontaneous transport is considered passive because…
it doesn’t require energy to move the molecule against the energy gradient
The need for energy to move the molecule against the energy gradient is a.k.a.
active transport
Calcium ions free in the cytosol is so minuscule compared to ions in other ICF because the majority usually appear sequestered in - _ and/or bound to proteins
membrane-bound organelles
Passive/spontaneous transport occurs from areas of _ energy to areas of _ energy
high to low
Food colouring in water is an example of _ transport
passive
The energy of a solution depends on the solute _ (and charge, if the solute is an ion)
concentration
Energy _ as solute concentration increases
increases; a type of positive feedback?
Solutes move passively _ their concentration gradient
down…high to low is down!
Transport of molecules against a membrane is called _ transport
active
The movement of a molecule into or out of the cell by its own thermal motion is _ _
simple diffusion
Transport proteins or _ mediate active transport
pumps
Transport of GLUCOSE from an area of lower to higher concentration is _ transport
active transport because it does not occur spontaneously, and requires energy for its initiation
Three driving forces occur: chemical, electrical and _
electrochemical
Driving forces is always from _-er to _-er
higher to lower
A ‘triangle’ followed a ‘C’ refers to the _ _
concentration gradient
Concentration gradient is used in reference to any difference in concentration between one membrane or another. T or F?
false - difference in concentration between one location or another not just differences across membranes
Molecules moving in an opposite direction move _ a concentration gradient
up/against a concentration gradient
A concentration gradient is a _ driving force
chemical
A membrane potential is a type of _ driving force
electrical
Ions are a.k.a…
electrolytes
Anions have a _ charge
negative
Cations have a _ charge
positive
A person’s total electric charge is _
zero because the number of cations vs anions is equal in the body
A person may pick up and emit electrical charges (picking up a negative charge and transmitting it) by…
rubbing your feet on carpet, rubbing a balloon on one’s head
In intracellular or extracellular fluid, cations and anions are present in _ numbers
unequal numbers, allowing a charge that can ensure the membrane’s potential
_ fluid contains a slight excess of anions (or negative ions) over cations
intracellular fluid (therefore membrane potential is usually negative)
Extracellular fluid contains a slight excess of _ ions
positive/cations
The excess negative and positive charges of ICF and ECF tend to be clustered close to the membrane because…
the excess cations move closer to the excess anions on either side of the membrane, like magnets
Units of electric potential on a cell’s membrane:
millivolts (mV)
The sign of the membrane potential (positive or negative) is taken to be the sign of the net charge _-side the cell
inside the cell
The membrane potential is typically _ because of the tendency for the ICF to be the same
negative membrane potential = what occurs INSIDE/intracellular
Vm’ is approximately _ _ millivolts
equals -70mV
Vm refers to the _ _ of a cell
membrane potential
Electrical current in biological systems is caused by _ movement
ion (i.e., chemical causes an electrical reaction)
Valence is a.k.a. _
charge or electrical charge (i.e., how + or - charge the ion is)
T OR F: uncharged molecules, such as glucose, are not affected by the membrane potential
true
Why aren’t uncharged molecules like glucose affected by the membrane potential?
they have an electrical driving force of zero, which wouldn’t impact or be impacted by membrane potential
The strength of the electrical driving force on an ion is a.k.a. the _
magnitude
T or F: cations are attracted by the positive charge inside the cell and have an outward-directed electrical driving force
False - cations are attracted by a NEGATIVE charge inside the cell and have an INWARD-directed electrical driving force. Since the membrane potential is typically negative/the ICF is negative, then it contains more anions. Therefore, the ECF has more cations/+, which would be attracted to their opposite, anions/-, which occur toward the ICF/inward-directed
If the electrical and chemical forces go in opposite directions, then the electrochemical force acts in the direction of the _ force
larger
If a physiologist finds _ potential, then the electrical driving force is said to be equal and opposite to the chemical driving force
equilibrium potential
Sodium ions (Na+) are typically found in higher concentrations _ of the cell, with its chemical force directed inward
outside a cell; more sodium in the ECF
The Nernst equation calculates the _ _ of a membrane
equilibrium potential
Ion’s equilibrium potential is shown as…
Ek, an chemical driving force
Ek is indicative of a/n _ driving force
chemical
The main chemical driving force is the…
ion’s equilibrium potential, which is based on the concentration gradient of that specific ion
The electrochemical driving force is defined as…
the net driving force of the electrical and chemical equilibrium potentials
Molecules that can travel across membranes: p_
permeants
A membrane that allows molecules through
permeable
Px is a symbol for…
the permeability of a membrane for a particular molecule
e.g., PNa is the permeability of Na+
Px refers to the permeability of the molecule. T or f?
False - refers to a membrane’s permeability for a molecule, since it does not make sense for a molecule to have permeability in general. For what? Rather, a membrane is or isn’t permeable for a molecule, and if it is, by what amount…
The factors that define a membrane’s permeability are:
lipid solubility of the diffusing substance/molecule
size and shape of diffusing molecule
membrane thickness
_
temperature
T or F: the more lipid soluble a substance is, the greater a membrane’s permeability to that substance
true
T or F: Tissues have similar thickness, whereas membrane thickness varies considerably.
True - membranes vary in their thickness, whereas tissue thickness is generally the same
The factor that has the strongest impact of a membrane’s permeability for molecule/s is…
the lipid solubility of the membrane
Most material is _philic, therefore it does not generally moving across a membrane with (simple) diffusion
hydrophilic; the membranes are fatty, which water repels
Fatty acids, steroid hormones, thyroid hormones, oxygen, carbon dioxide, and the fat-soluble vitamins (A, D, E, and K) can all do what?
permeate a cell membrane by (simple) diffusion
The equation ‘P A (triangle) C’ is for Fick’s law, a test for the…
permeability of molecules based on their ‘net flux’
Fick’s law is shown as ‘P _ (triangle) C’, with P = permeability of the molecule for the membrane, _ for the …, and ‘triangle C’ for the concentration gradient
‘P A (triangle) C’; A is for the membrane surface area
For testing the net flux of a membrane’s permeability, we consider that for a concentration gradient of a given size, the flux increases as _ gets larger.
permeability gets larger;
(triangle) C gets larger as P gets larger, since the membrane surface area (A) remains the same
net flux = P A (triangle) C
Is facilitated diffusion the same as active transport?
No, not necessarily
Simple diffusion is to passive transport as is _ _ to active transport
facilitated diffusion
_ are a type of transmembrane protein that uses conformational change to transport molecules across a membrane
carriers
A molecule must reach a _ _ before being taken by a carrier across a membrane
binding site
A carrier connects the molecule to the binding site and _ on the other side of the membrane, at which point it uses conformational change
fluid!
T or F: conformational change happens randomly
true, due to thermal agitation of the carrier protein
Thermal agitation of the carrier protein causes confirmation change of the molecule to happen _
randomly
T of F: a carrier can take one molecule from one side of a membrane to another, and can also grab a different one and go the opposite direction
true
T or F: concentration gradient is the only difference that impels facilitated diffusion, including the affinity of the binding site to the carrier
true - the affinity of the binding site to the carrier (the likelihood of a carrier being used on one side of a membrane vs another) is the same for facilitated diffusion
Diffusional equilibrium of a carrier occurs when…
the concentration gradient and the affinity of the binding site to the carrier are equal
The rate of facilitated diffusion is based on:
the magnitude of the concentration gradient
the number of carriers on the membrane, and…
_?
the transportation rates of the individual carriers (number, strength, speed)
The speed of facilitated diffusion is rated as molecules per _
second
T or F: increasing a relatively high concentration gradient will not have an effect on the carrier’s transportation rate
true, because the number of carriers would already be 100% in use going down the gradient as it is…the strength of the concentration won’t make a further difference
The rate of facilitated diffusion depends on the number of _
carriers/carrier proteins
Carriers are similar to _ in that altering their number increases the rate of action (for carriers the rate of facilitated diffusion) taking place
carriers are similar to enzymes, with their own levels affecting the rate of chemical reactions
A _ is a transmembrane protein that transports molecules via a pore that extends from one side of the membrane to the other
channel
T or F: channels are carriers
false - they’re similar, but not the same
Like carriers, _ are usually specific for certain substances or classes of substances for transporting molecules
channels are similar to carriers in that way
Most water diffuses across cell membranes through _, highly selective pores that permit water
aquaporins
Aquaporins differ in their:
permeability for water
selectivity, and
_?
location
T or F: water cannot cross cell membranes through ion channels
false - they can!
When a channel has numerous binding sites, ions move through the pore by “_”
jumping…from one site to the next
T or F: an empty CHANNEL’s binding sites are accessible from both sides of the membrane at the same time
true - that is not the case for carriers
In diabetes mellitus, the lack of insulin action means fewer _ transporters in the plasma membrane of these cells
GLUT4 transporters, a type of facilitated diffusion carrier protein
A lack of insulin action means fewer GLUT4 transporters in the plasma membrane of cells in a diabetes mellitus individual, so glucose uptake is _
decreased - glucose stays in the blood where it can have deleterious effects, and not taken up for energy resources
T of F: The rate of transport through ion channels depends on the total number of ion channels in the membrane
True, but specifically the rate depends on the number of OPEN ion channels
Carriers and channels differ because:
carriers bind to molecules whereas channels allow entry
carriers occur only one direction at a time, and…
_?
water cannot cross with a carrier, but they can across some channels, including ion channels
_ active transport uses ATP or some other chemical energy source directly to transport substsances
primary active transport uses ATP
secondary active transport is powered by a / _ that was previously created by primary active transport
concentration/electrochemical gradient
T or F: carriers differ from active transporters since the latter harnesses energy to drive the transport of molecules in a PREFERRED direction across a membrane, whereas the former does not
true - carriers are equally likely to transport molecules in either direction, provided there is no electrochemical gradient
The affinity of active transporters is greater when the _ _ is exposed to one side of the membrane than when it is exposed to the other side
binding site
A steady state indicates that concentration will not continue to change, but maintaining this state requires _
energy - active transport is affected by affinity for a molecule vs concentration gradient. if they’re equal, then energy is required to change that steady state, a type of equilibrium
Membrane proteins that perform primary active transport functions harness energy from ATP by catalyzing ATP _
hydrolysis
Membrane proteins that perform primary active transportation are like an enzyme, and as such are referred to as _
ATPases
THe - _ is present in nearly every cell and is crucial to several important physiological processes
sodium-potassium pump
THe sodium-potassium pump is present in nearly every cell and is crucial to several important physiological processes, including:
electrical signaling in neurons and …
the absorption of gluocse by intestinal epithelial cells
For each cycle of the pump, _ Na+ ions are transported out of the cell and _ K+ ions are transported into the cell
3 Na+ go out, 2 K+ go in
T OR F: The sodium-potassium pump uses active transport for the Na+ going out and the K+ going in
true
In each cycle of the pump, ATP molecules are hydrolyzed to produce the energy required for the process. It requires _ ATP molecule/s
ONE
T or F: An ordinary carrier’s binding sites can face either side of the membrane, allowing molecules transported in both directions, whereas for the Na+/K+ pump, binding sites change affinity when facing one side of the membrane vs the other
true
The binding site of the Na+/K+ pump faces _ to gather Na+ molecules
inward - Na+ are to be released
ATP hydrolysis occurs after three Na+ ions bind, resulting in _ of the pump protein
phosphorylation
Phosphorylation induces a conformational change in the protein of the Na+/K+ pump that turns the binding sites outward, so that Na+ can exit into the _
ECF
Pumps in the lining of the stomach transport _+ out of cells while transporting K+ into the same cells, responsible for the secretion of acid in the stomach
H+ (hydrogen)
_ triggers muscle contraction, therefore there are _+ pumps located in muscle cells
calcium; Ca2+
Ca2+ pumps are used in muscle contraction as well as on the _ _ _, where they transport calcium from the cytosol into the organelle, allowing the muscle cell to relax
smooth endoplasmic reticulum
Glucose oxidation is an example of an _ reaction, the release of energy in secondary active transport
exergonic reaction
ATP synthesis is a type of _ reaction, the creation of energy in secondary active transport
endergonic reaction
Co-transport of sodium and glucose is an example of a _ _ transport
secondary active transport
Antiport and exchange are other names for _, a secondary active transport mechanism
countertransport
Sodium-proton exchange, the inward flow of Na+ coupled with the outward flow of protons (H+) is indicative of _-transport, a secondary active transoprt
countertransport
T of F: direction of transport tells us which substance is being transported actively or which is flowing passively in secondary active transport
false - alone it doesn’t, but by the directions of the transported substances’ electrochemical gradients
(i.e., up its electrochemical gradient is active, whereas down is passive)
T or F: If the rate of transport by individual active transporters increases and/or the number of active transporters that are present in the membrane increase, the rate of OVERALL transport increases
true
The concentrations of the transported substance on either side of the membrane, the size of the electrochemical driving force for that substance and other variables affect the conditions under which an individual _ _ must operate
active transporter
Normally the composition of intracellular fluid remains fairly _
steady
Why is the composition of intracellular fluid fairly steady?
as substances are passively leaked across membranes, there are active processes transporting them in the opposite direction, maintaining the same amount within vs the same without (i.e., Na+ ions in ICF do not have a net change, although Na+ are simultaneously leaving and entering the cell)
The flow of water across a membrane down its concentration gradient is called _
osmosis (although not specific to water)
At body temperature, the concentration of pure water is _ molar
55.5 molar (NOT millimolar)
At body temperature the normal total solute concentration in ICF is _ millimolar
300 mM or 0.3 M
Concentrations of solutions are usually described in terms of the concentration of _, not solvent
solute (i.e., Na+ measured vs the water in a sodium solution)
The total solute particle concentration of a solution is known as its _
osmolarity
One mole of solute particles is referred to as 1 _
osmole (vs. 10% glucose would be 0.1 mole of glucose, an osmolarity of 0.1 osmolar)
T or F: 10% glucose solution (0.1 mole) is 0.1 osmolar whereas 10% NaCl solution (0.1 mole) is 0.2 osmolar. Also, a glucose (0.1 mole) and NaCl (0.1) solution is 0.3 osmolar
true - glucose is one molecule or solute particle, so it’s a straight percentage. NaCl is TWO solute particles, so it’s split to 0.2 osmolar. A glucose and NaCl (0.1 mole each) would also be 0.3 osmolar, since there are 3 solute particles in the solution
1 mOsm solution contains 1 milliosmole, or the equivalent of 1/_ of an osmole
1/1000 osmole = 1 milliosmole
The normal osmolarity of ICF and ECF is approx _ mOsm, which means that its total solute concentration is (SAME NUMBER) per litre
300 mOsm = 300 milliosmoles per litre
If both ICF and ECF solutions are 300 milliosmolar (300 mOsm), they are considered )-osmotic
iso-osmotic
A solution whose osmolarity is higher than another is said to be _osmotic, whereas its opposite is _-osmotic
higher is hyperosmotic, lower is hypo-osmotic
T or F: when 2 solutions are iso-osmotic, they have the same solute concentration and the same water concentration
true
_ pressure is another term that describes a solution’s total solute concentration
osmotic pressure
The ‘pi’ symbol is an indirect measure of a solution’s _ _
solute concentration
As the total solute concentration (osmolarity) of a solution increases, the osmotic pressure _
increases
As water moves from a lower to a higher solute concentration, water is flowing from _-er to _-er osmotic pressure
lower to higher osmotic pressure
As water moves from a lower to a higher solute concentration, it moves _ the osmotic pressure gradient (‘triangle’ ‘pi’)
up the osmotic pressure gradient
When water moves up a gradient of osmotic pressure, it is technically moving down a _ gradient - its own
chemical gradient of water/concentration gradient of water moves to where there is less water and more solution, therefore it moves up a low solute concentration to a higher solute concentration
_ is a function of the concentration of nonpermeating solutes outside a cell relative to the concentration inside the cell
tonicity
A solution is said to be _ when it does not alter cell volume
isotonic
A solution that causes cells to _ is hypertonic
shrinking cells suggests a hypertonic solution - more solute particles mean taking water out of the cell
A solution that causes cells to swell is _
hypotonic - less solute particles and more water, causing swelling of the cellsj
T or F: a solution’s tonicity is affected by the concentration of any permeant solutes that may or may not be present
false - tonicity doesn’t care about concentration of permeant solutes; it only cares about NONPERMEATING SOLUTES within relative to those outside
T OR F: Osmotic pressure decreases as the concentration of nonpermeating solute rises
false - increased pressure due to increased concentration
Osmotic pressure depends on the total … solute concentration rather than the molecular identities of the solutes
nonpermeating solute concentration
The _ _ of a solution is given by the following equation: ‘pi’ = CRT
osmotic pressure
‘pi’ = CRT
C = total solute concentration
R = universal gas constant
T = absolute temperature
_ is the total concentration of permeant and impermeant solutes
osmolarity
Tonicity is the concentration of impermeant solutes relative to _
ICF
A cell containing 300 mOsm impermeant solutes in a solution containing impermeant solutes at half that concentration (150) will see what happening?
water swelling into the cell, since there is a difference in tonicity (i.e., the ECF is hypotonic, which propels water moving into the cell
0.9% saline solution (Na = 23, Cl = 35) has the following osmolarity…?
0.9% solution = 9 g/100 mL, with 23 + 35 = 58 g/mole
9g/ (58g/mole) = 0.155 moles or 155 mmoles per litre
NaCl is two particles in water, therefore mmoles x 2 = mOsm
155 mM * 2 particles = 310 mOsm
solution is iso-osmotic (close to 300 mM) and isotonic solution
What is the osmolarity of 5% dextrose? C6H12O6 (3 particles; C = 12, H = 1 and O = 16)
5% solution = 5 g/100 mL
C = 6 * 12 + (12 * 1) + (16 * 6) = 180 g/mole
5 g/ (180 g/mole) = 0.278 mole or 278 mM per litre
since dextrose remains one particle in water, we say that…
278 mM * 1 particle = 278 mOsm
iso-osmotic solution compared to body fluids, but it is hypotonic (similar to urea), since it is less than 300 mOsm
Osmolarity and -osmotic state relative to body fluids of:
200 mM solution of KCl
KCl has 200 mM or 200 mmoles potassium and 200 mmoles Cl in 1 litre of fluid =
200 + 200 = 400 mOsm
solution is HYPERosmotic relative to body fluids (which are 300 mOsm)
Osmolarity and -osmotic state relative to body fluids of:
100mM solution of MgCl2
100 mmoles of magnesium, (2 x 100 mmoles of Cl = 200 mOsm or chloride in 1 litre of fluid
100 + 200 mmoles = 300 mOsm
iso-osmotic to body fluids
Osmolarity and -osmotic state relative to body fluids of:
50 mM CaCl2 in 250 mL of water
50 mmoles /250 ml = _/ 1000 mL = 200 mM
(200 mM x 1 Ca) + (200 mM x 2 Cl = 400 mM) = 600 mOsm
HYPERosmotic to body fluids
For a substance crossing a cell membrane, the chemical driving force
a) Depends only on the concentration gradient, regardless of whether the substance is an ion.
b) Depends only on the concentration gradient if the substance is uncharged, but also depends on the electrical force if the substance is an ion.
c) Is the total driving force on the substance, even if it is an ion.
d) Is the force that pushes molecules across the membrane, but only if the substance is actively transported.
e) Always favors movement of a molecule into the cell.
a) Depends only on the concentration gradient, regardless of whether the substance is an ion.
Which of the following is located in greater concentration inside cells compared to outside?
a) Potassium ions
b) Sodium ions
c) Proteins
d) Potassium and sodium ions are both located in greater concentration inside cells.
e) Potassium ions and proteins are both located in greater concentration inside cells
e) Potassium ions and proteins are both located in greater concentration inside cells
One example of primary active transport is the
a) Transport of Ca2+ up an electrochemical gradient by a protein that hydrolyzes ATP.
b) Transport of Ca^^ up an electrochemi- cal gradient by a protein that couples Ca^^ flow to the flow of Na^ down an electrochemical gradient.
c) Movement of Ca^^ down an electro- chemical gradient through channels.
d) Transport of glucose molecules down a concentration gradient by carriers.
e) Transport of glucose up a concentra- tion gradient by a protein that couples glucose flow to the flow of Na^ down an electrochemical gradient
a) Transport of Ca^ ^ up an electrochemical gradient by a protein that hydrolyzes ATP
the rest of the options are secondary active transport or passive transport
If a certain anion is located in greater concentration inside the cell and a negative membrane potential exists, then which of the following statements is true?
a) The electrical force on the anion tries to move it into the cell.
b) The chemical force on the anion tries to move it into the cell.
c) The equilibrium potential for the anion is a positive value.
d) Both a and c are correct.
e) All of the above are correct
c) The equilibrium potential for the anion is a positive value.
Given that the potassium equilibrium potential is —94 mV and the sodium equi- librium potential is + 60 mV, which of the following statements is true for forces act- ing on sodium and potassium when a cell is at -70mV?
a) The electrochemical gradient for Na^ tries to move it into the cell.
b) The electrochemical gradient for K+ tries to move it into the cell.
c) Both a and b are correct.
d) Neither a nor b is correct
a) The electrochemical gradient for Na^ tries to move it into the cell.
When the membrane potential is equal to the equilibrium potential of Na+ (£’Na = +60mV)
a) Na^ moves into a cell down its elec- trochemical gradient
b) Na^ moves out of a cell down its elec- trochemical gradient.
c) The net flux of Na^ is zero because it is at equilibrium
c) The net flux of Na^ is zero because it is at equilibrium
The osmotic pressure of a solution de- pends on
a) The concentrations of aU solute par- ticles contained in it.
b) The concentrations of aU permeant solute particles contained in it.
c) The concentrations of all impermeant solute particles contained in it.
d) The pressure exerted on the solution by the atmosphere.
e) The volume of water in which the sol- ute particles are dissolved.
a) The concentrations of aU solute par- ticles contained in it.
Assuming that only impermeant solutes are present, which of the following will occur when a cell is placed in a solution whose osmolarity is 200 mOsm?
a) Water will move into the cell.
b) Water will move out of the cell.
c) Water will not cross the cell membrane
a) Water will move into the cell.
A solution is hypotonic if
a) The concentration of aU solutes con- tained in it is less than 300 mOsm.
b) The concentration of all permeant solutes contained in it is less than 300 mOsm.
c) The concentration of aU impermeant solutes contained in it is less than 300 mOsm.
d) Osmolarity is less than 300 mOsm
c) The concentration of aU impermeant solutes contained in it is less than 300 mOsm.
Movement of Na^ in sodium-linked glucose transport; in sodium-proton exchange, and via the sodium-potassium pump are all examples of
a) Primary active transport.
b) Passive transport.
c) Mediated transport.
d) Simple diffusion
c) Mediated transport.
Which of the following molecules would be most likely to cross the lipid bilayer by simple diffusion?
a) A small polar molecule
b) A large polar molecule
c) A small nonpolar molecule
d) A large nonpolar molecule
c) A small nonpolar molecule
Assuming that a substance is uncharged and is transported across a membrane by carriers, the net flux of that substance will tend to increase as
a) The membrane surface area decreases.
b) The magnitude of the concentration gradient decreases.
c) The membrane potential becomes more positive.
d) The number of carriers in the mem- brane increases.
e) All of the above
d) The number of carriers in the mem- brane increases.
What do active transporters and carriers have in common?
a) They both transport molecules up electrochemical gradients.
b) They both transport molecules down electrochemical gradients.
c) They both transport lipid-soluble sub- stances preferentially.
d) They both utilize ATP to transport molecules.
e) They both are specific for certain molecules.
e) They both are specific for certain molecules.
Substances that cross cell membranes by simple diffusion are mostly (hydrophilic/ hydrophobic)
hydrophobic (because they cross a LIPID/fat membrane
A channel carries out (active/passive) sol- ute transport
passive - ion channels can have water flow through like it ain’t no thang
In simple diffusion, an uncharged solute always flows from a region of higher con- centration to a region of lower concentra- tion, (true/false)
true
In facilitated diffusion, passive flow of an uncharged solute always goes from higher to lower concentration, (true/ false)
true
When a membrane potential is positive, there is an excess of cations over anions inside the cell, (true/false)
true - membrane is positive which are cations, and an excess of the would mean a + membrane potential
Transport of water from the bloodstream to the lumen of the intestine is an exam- ple of (secretion/absorption)
secretion
A cell will shrink if it is placed in a hyper- tonic solution, (true/false)
true
When water diffuses across a membrane, it normally flows from a region of higher osmotic pressure to a region of lower os- motic pressure, (true/false)
false - water tends to go from lower osmotic pressure to higher osmotic press - it is the water that reduces osmotic pressure/higher concentration of solute
When more than one ion species (i.e., Na+ and K+) is present on both sides of the membrane, the chemical driving force acting on Na+ will include ________.
A) the most concentrated ion only
B) sodium only
C) all ions present
D) all positively charged ions
E) all negatively charged ions
B) sodium only
chemical driving forces acting on an individual ion species remains on itself only
________ is a reflection of the unequal distribution of positive and negative ions across the plasma membrane.
A)
Electrochemical driving force
B)
Chemical gradient
C)
Membrane potential
D)
Chemical driving force
E)
Extracellular potential
C) membrane potential
seems to only care about the electrical potentiality, or membrane potential than anything else
Which of the following factors does NOT directly affect the direction or magnitude of the electrical driving force?
A)
the amplitude of membrane potential
B)
an ion’s charge
C)
the sign of the membrane potential
D)
the quantity of charge carried by an ion
E)
the molecular weight of an ion
E) the molecular weight of an ion
Which of the following is NOT a determinant of the magnitude and direction of the equilibrium potential for an ion?
A)
valence of the ion
B)
lipid solubility of the ion
C)
concentration difference
D)
direction of the concentration difference
E)
charge of the ion
B) lipid solubility of the ion
If a positively charged ion is more concentrated outside the cell, the forces required to balance the chemical gradient would be directed ________. Thus, the equilibrium potential for this ion would be ________ charged.
A)
inward : negatively
B)
outward : positively
C)
outward : negatively
D)
inward : positively
E)
outward : neutrally
B) outward: positively
in this instance, to balance what is so strong outside of the cell, then it would have to look outward to balance the strong + charge there. Overall, the charge would be positive since it is more positive than negative
whereas in normal situations, there are more anions inside the cell which means to balance it is to go inward, and the charge would be -
Which of the following cells would have a greater electrical attraction for sodium ions to enter the cell?
A)
cell with membrane potential = +20 mV
B)
cell with membrane potential = -70 mV
C)
cell with membrane potential = 0 mV
D)
cell with membrane potential = -90 mV
E)
cell with membrane potential = -50 mV
D) cell with membrane potential = -90 mV
if the interior of the cell is -90, then the external sodium ions are more excited about going inside, vs. a positive charge which would not elicit any change. Plus, the moment to move into the cell is at or after -70, so -90 is more than that so it’s the answer
If a positively charged ion is more concentrated inside the cell, the forces required to balance the chemical gradient would be directed ________. Thus, the equilibrium potential for this ion would be ________ charged.
A)
outward : neutrally
B)
inward : negatively
C)
outward : positively
D)
inward : positively
E)
outward : negatively
B) inward : negatively
The potassium equilibrium potential is -94 mV. This means that ________.
A)
at -94 mV, potassium movement is opposed exactly by sodium movement
B)
at -94 mV, the chemical force for potassium movement is zero
C)
at the resting membrane potential of neurons, potassium is at equilibrium
D)
at -94 mV, the chemical force for potassium movement is opposed exactly by the electrical force
E)
at -94 mV, the electrical force for potassium movement is zero
D)
at -94 mV, the chemical force for potassium movement is opposed exactly by the electrical force
An anion has an equilibrium potential of -40 mV. What direction are the chemical and electrical forces acting on the anion at the resting membrane potential (-70 mV)?
A)
Both the chemical and electrical forces are directed out of the cell.
B)
There is insufficient information to answer this question.
C)
The chemical force is directed out of the cell and the electrical force is directed into the cell.
D)
Both the chemical and electrical forces are directed into the cell.
E)
The chemical force is directed into the cell and the electrical force is directed out of the cell
E)
The chemical force is directed into the cell and the electrical force is directed out of the cell
An anion is found in greater concentration inside the cell than outside. Which of the following statements best describes forces acting on the anion at the resting membrane potential (-70 mV)?
A)
The chemical force is directed out of the cell and the electrical force is directed into the cell.
B)
The chemical force is directed into the cell and the electrical force is directed out of the cell.
C)
There is insufficient information to answer this question.
D)
Both the chemical and electrical forces are directed into the cell.
E)
Both the chemical and electrical forces are directed out of the cell.
C)
There is insufficient information to answer this question.
Oxygen diffuses from blood into cells down its concentration gradient. As cells become more active and oxidative phosphorylation increases in the cell, which of the following occurs?
A)
The concentration gradient for oxygen increases and oxygen movement into the cell increases.
B)
The concentration gradient for oxygen decreases and oxygen movement into the cell decreases.
C)
The concentration gradient for oxygen decreases and oxygen movement into the cell increases.
D)
The concentration gradient for oxygen and its rate of movement into the cell do not change.
E)
The concentration gradient for oxygen increases and oxygen movement into the cell decreases.
A)
The concentration gradient for oxygen increases and oxygen movement into the cell increases.
Which of the following will NOT increase the net flux of an ion across a membrane?
36)
______
A)
increased concentration gradient across the membrane
B)
enhanced surface area
C)
elevated permeability of the membrane
D)
reduced surface area
E)
more channels for that ion in the membrane
D) reduced surface area
we are asking for what will NOT INCREASE, which would be its opposite, i.e., reducing the surface area
1 mole of a substance = 6 x 10 ^_ molecules
6 x 10 ^23 molecules
1 mole of glucose = _ g
180
1 mole of NaCl = _g
58.5 grams
Is plasma membrane for the urinary system isotonic or iso-osmotic? Why?
isotonic because it does not allow urea to enter cells once removed, whereas an iso-osmotic solution could
