The repolarization phase of the action potential in a neuron is driven by the:
a) closure of potassium channels
b) closure of calcium channels
c) opening of sodium channels
d) closure of sodium channels and opening of potassium channels
e) opening of sodi
d) closure of sodium channels and opening of potassium channels
An action potential originates at the _____ and travels along the axon until it reaches the _____.
a) axon terminal : axon hillock
b) dendrite : axon terminal
c) axon hillock : dendrite
d) dendrite : axon hillock
e) axon hillock : axon terminal
e) axon hillock : axon terminal
Which type of chemical messenger, when released, binds to receptors on the same cell that released the chemical messenger?
a) paracrine
b) autocrine
c) hormone
d) endocrine
e) neurotransmitter
b) autocrine
Which of the following second messengers, when released by the actions of phospholipase C, will directly activate the enzyme protein kinase C?
a) inositol triphosphate
b) inositol biphosphate
c) calcium
d) diacylglycerol
e) cAMP
d) diacylglycerol
If a negatively charged ion is more concentrated outside the cell, the forces required to balance the chemical gradient would be directed _____, and the equilibrium potential for this ion would be a _____ number.
a) outward; negative
b) outward; positive
a) outward; negative
Which of the following is NOT a factor involved in the determination of resting membrane potential?
a) concentration of sodium
b) concentration of potassium
c) presence of sodium channels
d) presence of potassium channels
e) concentration of sodium recept
e) concentration of sodium receptors
In its active form, a G protein has a GDP bound to its alpha subunit
a) this is true
b) this is false
b) this is false
If the concentration of magnesium ions (Mg2+) inside teh cell is 1.2mM, and the concentration of ions outside the cell is 58mM, what would be the approximate equilibrium potential for magnesium
a) 51mV
b) -103mV
c) 75mV
d) 103mV
e) -51mM
a) 51mV
What is phosphatidylinositol-4,5-biphospate?
a) a second messenger
b) a phospholipid in the cell membrane
c) an enzyme that catalyzes the formation of a second messenger
d) a component of a G protein
e) more than one of the above is correct
b) a phospholipid in the cell membrane
Resting membrane potential results from:
a) an uneven distribution of ions across the cell membrane
b) differences in membrane permeability to Na+ and K+
c) both of these
d) neither of these
c) both of these
In neuron membranes, what types of ion channels allow ions to move across the membrane at rest, and thereby contribute to resting membrane potential?
a) resting channels
b) potentials-gated channels
c) leak channels
d) voltage-gated channels
e) ligand-gat
c) leak channels
If resting neuron's membrane becomes more permeable to potassium ions:
a) the inside of the membrane will become more positively charged
b) the membrane will depolarize more rapidly
c) the membrane will become hypopolarized
d) the hyperpolarization at the
e) the membrane will become hyperpolarized
Resting membrane potential in a typical nerve cell is approximately:
a) +90mV
b) -70mV
c) +30mV
d) 0mV
e) -90mV
b) -70mV
Slow channels are identified as such because, once the receptor is bound by the ligand, the receptor directly activates a(n):
a) G protein
b) ion channel
c) enzyme
d) hormone response element
e) RNA polymerase
a) G protein
Which of the following cells would have the greatest electrical attraction for sodium ions to enter the cell:
a) cell with membrane potential = -70mV
b) cell with membrane potential = -90mV
c) cell with membrane potential = -50mV
d) cell with membrane pot
b) cell with membrane potential = -90mV
Which of the following statements about sodium is FALSE?
a) at the sodium equilibrium potential, there is an electrical force driving sodium ions out of the cell
b) in all human cells, there is a chemical force driving sodium into the cell
c) at resting m
d) at the potassium equilibrium potential, there is an electrical force driving sodium ions out of the cell
Which of the following describes the signal transduction mechanism for estrogen, a steroid hormone?
a) opening of fast ligand-gated channels
b) activation of an enzyme-linked receptor
c) activation of the cAMP-second messenger system
d) opening of slow li
e) altering transcription of genes
Which of the following statements best describes the function of tyrosine kinase?
a) it catalyzes the phosphorylation of proteins inside the cell
b) it catalyzes the phosphorylation of proteins outside the cell
c) Both a) and b) are correct
a) it catalyzes the phosphorylation of proteins inside the cell
As the charge on the membrane of a typical neuron approaches 0mV from -55mV, the cell membrane is considered to have:
a) repolarized
b) hyperpolarized
c) depolarized
d) become more difficult to simulate
e) both b) and d) are correct
c) depolarized
For the voltage-gated sodium channel to allow sodium into the cell:
a) the activation and inactivation gates must both be open
b) only the activation gate must be open
c) only the inactivation gate must be open
d) the inactivation gate must be closed shor
a) the activation and inactivation gates must both be open