big sib review

Question 1

fours factors that influence the amplitude of EPP

Answer 1

strength of the inward Ca++ current in presynaptic cell

Question 2

Which is the FALSE statement about the peak of the axonal action potential?

Answer 2

Most, if not all, Na channels are in the closed state.

Question 3

An artificial membrane is composed solely of phospholipids. Which of the following functional properties would you expect this membrane to exhibit?

Answer 3

High capacitance

Question 4

Passive diffusion across a cell membrane differs from facilitated diffusion in that:

Answer 4

Facilitated diffusion exhibits a transport maximum.

Question 5

Ion channels:

Answer 5

have multiple membrane spanning groups

Question 6

A medical student was shown to have a lower than normal plasma potassium concentration. Which of the following would you observe?

Answer 6

Cellular resting potentials would be hyperpolarized from their normal values.

Question 7

The chloride channel in the membrane of skeletal muscle fibers :

Answer 7

aids in the repolarization of the muscle fiber

Question 8

(open the attached Table) Assuming the resting potential of this cell is a Nernst equilibrium for K+ which of the following values would be expected if you were to record a resting potential from this cell:

Answer 8

+ 60 mV

Question 9

(Open the attached Table) When stimulated, the membrane potential of this cell changes to 0 mV. Which of the following conductances could account for this new membrane potential?

Answer 9

membrane solely permeable to Cl-

Question 10

An increased duration of the axonal action potential can be caused by:

Answer 10

blockade of inactivation of the voltage-gated Na channel

Question 11

Which of the following factors is NOT required to determine the current generated by an ion as it moves through a channel:

Answer 11

the capacitance of the membrane

Question 12

The following data were obtained from a whole-cell patch clamp study of a neuronal membrane:

             i.   The current voltage relationship was linear over all ranges of voltages studied.

            ii.  The current was found to be 0 at about -10 mV.

        From this data, which of the following is most likely?  Assume that the concentration gradients are typical of a normal cell.

Answer 12

The channel involved is not voltage-dependent.

Question 13

Which of the following is associated with the Node of Ranvier?

Answer 13

a high density of voltage-gated Na channels

Question 14

Which of the following is NOT associated with activation of the voltage-gated K channel?

Answer 14

the upsweep of the action potential

Question 15

Myelinated axons conduct an action potential faster than non-myelinated axons because:

Answer 15

the time constant is faster

Question 16

Select the FALSE statement about myelin basic protein.

Answer 16

It is an axonal membrane protein that promotes binding of myelin to the axon.

Question 17

The calcium channel found in a pre-synaptic nerve terminal:

Answer 17

produces an inward calcium current

Question 18

are terminated by removal of acetylcholine from the synaptic junction

Answer 18

end plate potentials

Question 19

Calcium release during excitation-contraction coupling in skeletal muscle is most likely terminated by:

Answer 19

closure of the dihydropyridine sensitive channel

Question 20

Relaxation of skeletal muscle after a contraction is controlled by:

Answer 20

the uptake of calcium by the SR Ca ATPase

Question 21

The binding of ATP to the myosin head during the cross-bridge cycle:

Answer 21

promotes detachment of the cross-bridge

Question 22

Greater amounts of tension can be measured from a skeletal muscle during tetany compared to during a twitch. This is because:

Answer 22

any series elastic elements are maximally stretched during the first few stimuli of tetany

Question 23

If you increase the length of a resting skeletal muscle to twice its normal body length and then stimulate to produce a maximal isometric contraction, you will find that:

Answer 23

active tension development in the muscle at the new length will be greatly reduced

Question 24

Which of the following is considered to be the major factor in the ‘moment to moment’ regulation of skeletal muscle tension?

Answer 24

the recruitment of motor units

Question 25

Select the FALSE statement about contraction in unitary smooth muscle.

Answer 25

Calcium entry across the plasma membrane is negligible.

Question 26

Select the FALSE statement about gap junctions.

Answer 26

They reduce synchronous activation of the coupled cells.

Question 27

Recruitment of Type 1 motor units:

Answer 27

generally occurs before Type II motor unit recruitment

Question 28

Plasma calcium levels were found to be 5mM instead of a normal value of 1.5mM. Which of the following is a consequence of this change in extracellular calcium

Answer 28

The amount of current needed to initiate an axonal action potential is higher than normal.

Question 29

Which of the following relationships describes the effect of the impermeant anions inside the cell on the diffusable ions?

Answer 29

The Donnan equilibrium

Question 30

involves direct coupling of the transporter to hydrolysis of high energy bonds.

Answer 30

Primary active transport

Question 31

Select the False statement about membrane capacitance

Answer 31

It is created by the presence of channels in the membrane.

Question 32

The treatment of a cell membrane with a neurotransmitter results in a rapid conductance change and a depolarization. The channel involved in this process is most likely a

Answer 32

primary ligand-gated channel.

Question 33

An unknown non-ionic substance, ‘x’, is found to move into a cell. Which of the following would clearly identify the movement of ‘x’ as simple diffusion?

Answer 33

The relationship between flux of ‘x’ and the concentration in the outside medium is linear over all concentrations.

Question 34

A resting potential of a cell hyperpolarizes when the medium is changed. This hyperpolarization is most readily explained if the new medium contained

Answer 34

less potasium than normal.

Question 35

Select the FALSE statement about the Na/k Pump.

Answer 35

Keeps the membrane potential at the equilibrium potential for K+.

Question 36

Which ionic channel would produce the greatest amount of membrane depolarization when it is opened by a neurotransmitter?

Answer 36

A channel specifically permeable to Ca2+.

Question 37

The relationship between membrane potential and the log of the external concentration of K+ ion was plotted for an unknown cell. When the slope of this curve was found, it had a value of about 50. This most likely means that

Answer 37

the Goldman-Hodgkin-Katz equation is a better estimate of V m than the Nernst in this case.

Question 38

Select the FALSE statement about the K+ conductance associated with the axonal action potential.

Answer 38

The peak of K+ conductance coincides with the peak of Na+ conductance.

Question 39

The spread of local currents during propagation of an axonal action potential

Answer 39

is decremental with distance from the source of the current

Question 40

Select FALSE statement about the node of Ranvier

Answer 40

It has a low density of voltage-gated. Na+ channels