Exam 1

A neuron that innervates (i.e., makes synaptic contact with) a large number of other neurons: A. represents divergent neural signaling. B. must fire at very high frequencies to be useful. C. represents convergent neural signaling. D. can fire only at very low frequencies. E. represents massive neural integration.

A

An ion has a charge of +2 and is found at about 10,000X higher concentration OUTSIDE the cell. According to the Nernst equation, the ion equilibrium potential should be closest to... A. +120 mV B. -60 mV C. -180 mV D. -90 mV E. + 60 mV

A

Driving force is the "push" on an ion and is determined by the difference between _________ and ________. A. cell voltage and ion equilibrium potential B. resistance and conductance C. current and voltage D. resistance and current

A

Hodgkin and Katz discovered that the resting membrane potential changes by _______ mV per tenfold change in K+ concentration. A. 58 mV B. 90 mV C. 29 mV D. 70 mV E. 120 mV

A

In voltage-clamp experiments, the early current of a cell will disappear when.... A. the voltage is set at the equilibrium potential for sodium B. the voltage is set to zero C. any time the voltage is made more positive than resting potential D. the voltage is made more positive than the potassium equilibrium potential

A

Two solutions are separated by a permeable membrane. Assume only a single ion (ion A) is used. Solution X contains 100 mM of ion A, while solution Y contains 10 mM of ion A. At equilibrium, the movement of ion A... A. would be equal in both directions B. would favor moving toward solution Y C. would favor moving toward solution X D. would be entirely stopped (zero movement)

A

What would occur if the ATPase pumps in a neuron stopped functioning? A. Concentration gradients would not be maintained across the membrane B. At rest, sodium would continuously depolarize the cell C. At rest, potassium would continuously depolarize the cell D. During the action potential, the sodium channel would not inactivate E. During the action potential, the voltage-gated ion channels would remain closed

A

Which best describes the absolute refractory period? A. a cell is incapable for initiating an action potential due to the inactivation of voltage-gated sodium channels B. a cell is incapable of initiating an action potential due to the strong conductance of K+ which keeps the cell near the K+ equilibrium C. a hyperpolaried cell is capable to initiating an action potential but requires a stimulus larger than the original stimulus D. a cell is capable of initiating an action potential but the action potential will be smaller than usual due to inactivation of voltage-gated sodium channels

A

Which is TRUE of voltage-gated channel kinetics underlying the action potential? A. sodium channels are faster to open than potassium channels B. potassium channels are faster to inactivate than sodium channels C. threshold for channel openings is typically between 0 - +10mV D. sodium channels close at the same time as potassium channels

A

Which occurs during the depolarization phase of an action potential? A. sodium current exceeds that of potassium B. the sodium driving force gets larger C. potassium leak slows down D. the potassium driving force gets smaller E. potassium channels open faster than sodium channels

A

Which treatment was shown to eliminate the early inward current in squid giant axons? A. Removal of external sodium B. Doubling of external sodium C. Removal of external potassium D. Addition of chloride E. Doubling of external potassium

A

In what way are ion channels similar to active transporters? A. Both maintain ion concentration gradients. B. Both actively move ions from one side of the membrane to the other. C. Both are proteins. D. Both create ion concentration gradients. E. Both enable non-selective for ion permeability.

C

Which is TRUE about typical, resting neurons? A. The concentration of sodium ion is greater inside the cell than outside. B. The plasma membrane is completely impermeable to potassium ions. C. The permeability of the plasma membrane to potassium ions is much greater than its permeability to sodium ions. D. The plasma membrane is most permeable to sodium ions. E. The plasma membrane is completely impermeable to sodium ions.

C

Which of the following pairs of proteins and inhibitors are both correctly matched? A. voltage-gated potassium channel = 4-AP; voltage-gated sodium channel = gabapentin B. voltage-gated calcium channel = omega-agatoxin; chloride leak channel = conotoxin C. voltage-gated sodium channel = TTX; voltage-gated potassium channel = TEA D. voltage-gated calcium channel = TEA; Na/K pump = oubain

C

Which substance binds only at the extracellular domain of a ligand-gated ion channel? A. H+ B. Ca2+ C. Neurotransmitter D. cAMP E. cGMP

C

An action potential is a(n) _______ change in the electrical potential across the nerve cell membrane. A. unidirectional B. random C. permanent D. all-or-nothing E. single

D

Which function is a characteristic primarily of neurons only, and not glia? A. Repairs the nervous system B. Prevents regeneration of the nervous system C. Supports electrical signals D. Transmits action potentials E. Produces myelin

D

From which part of the nervous system do cells that innervate neuromuscular junctions originate? A. Visceral motor division of PNS B. Autonomic nervous system C. PNS D. Somatic motor division of PNS E. CNS

E

Mathematically, current can be calculated as _________ x ____________ A. membrane potential; voltage B. Faradays; Ohms C. conductance; resistance D. voltage; conductance E. driving force; conductance

E

Which conclusion can be drawn from Hodgkin and Huxley's studies of K+ and Na+ conductances? A. Both conductances depend on voltage. B. Both conductances exhibit the property of time-dependent activation. C. K+ conductance reaches its maximum with a pronounced delay. D. Unlike K+ conductance, Na+ conductance reaches its maximum and inactivates rapidly. E. All of the above

E

Which glial cell type serves as a resident immune cell in the central nervous system? A. Schwann cell B. Glial stem cell C. Astrocyte D. Oligodendrocyte E. Microglia

E

Which is TRUE at cell resting potential? A. Potassium is at higher concentration OUTSIDE the cell B. driving force on potassium wants to push potassium INTO the cell C. sodium has greater conductance than potassium D. the Na/K-pump moves potassium OUT of the cell and moves Na INTO the cell E. driving force on sodium wants to push sodium INTO the cell

E

Which is the voltage-sensor of a voltage-gated sodium channel? A. the inactivation gate B. the p-loop C. the N-terminus D. 6TM E. S4

E

transporters....

Transport of some ions down their concentration gradient and others up their gradient

How does the resting membrane potential of a typical neuron compare to the equilibrium potential (calculated by the Nernst equation) for potassium? A. The resting membrane potential is not exactly equal to the equilibrium potential for potassium because of variation among neurons. B. The resting membrane potential is not exactly equal to the equilibrium potential for potassium because the membrane has some resting permeability to species other than potassium. C. The resting membrane potential is exactly equal to the equilibrium potential for potassium. D. The resting membrane potential is not exactly equal to the equilibrium potential for potassium because rapid fluctuations in membrane potential prevent accurate measurements. E. The resting membrane potential is not exactly equal to the equilibrium potential for potassium because potassium does not contribute to the resting membrane potential.

B

The typical voltage-gated K+ channel is made up of _______, each of which contains helical membrane-spanning domains with a _______ between them. A. two protein subunits; pore loop B. four protein subunits; pore loop C. four domains; pore loop D. two protein subunits; pore E. two domains; selectivity filter

B

The voltage-clamp method holds _________ steady, while recording input of __________ to balance the __________ of the cell. A. resistance; capacitance; permeability B. voltage; current; current C. current; voltage; conductance D. conductance; voltage; current

B

What is the predominant factor which affects the permeability of a membrane to a specific ion? A. Concentration of the ion outside the cell B. Number of open ion channels specific for that ion C. Electrical charge of the ion D. Concentration of the ion inside the cell E. Size of the ion

B

Which equation calculates cell resting potential using permeabilities and ion concentrations for all of sodium, potassium, and chloride at the same time? A. Ohm's law B. Goldman-Hodgkin-Katz (GHK) equation C. current equation D. Nernst equation

B

Which is ALWAYS true for ion movements? A. ion movements of sodium and potassium are always inward at voltages experienced by real cells B. ion movements push the cell toward that ion's equilibrium C. all ion movements stop at cell resting potential D. ion movement is always positive when at that ion's equilibrium potential

B

Which of the following is a demyelinating disease of axons in the CNS? A. Guillain-Barre syndrome B. Multiple Sclerosis C. Alzheimer's disease D. Zika

B

Which statement accurately describes neural and glial cells? A. Glial cells and neurons rapidly transmit long-range electrical signals B. Exocytosis and endocytosis are important for synaptic communication C. The endoplasmic reticulum is concentrated in axons D. Neither Cell type relies on cytoskeletal filaments

B

Which technique would you use to study individual ion channel activities, without the effects of intracellular regulators? A. Conventional voltage clamp B. Outside-out patch clamp C. Cell-attached patch clamp D. Whole-cell patch clamp

B