Neuro Bio Test 1
During the overshoot phase of an action potential, membrane potential briefly reaches a value near __________ mV
+30
If the distribution of EPP amplitudes has peaks at 0.4 mV, 0.8 mV, 1.2 mV 1.6 mV and 2.0 mV, what is the most likely amplitude of the MEPP?
0.4 mV
What is the likely source of the quanta that make up the EPP?
Fusion of individual synaptic vesicles with the plasma membrane
How would the application of a Ca++ channel blocker affect the function of a synapse?
It would eliminate the postsynaptic potential and the presynaptic Ca++ current
Hodgkin and colleagues found which of the following ratios for relative permeability to ions during resting vs action potential
Resting potential Pk, Pna, Pcl= 1, 0.04, 0.45. Action potential Pk, Pna, Pcl = 1:20:.045
Which cell produces myelin in the nerves of the peripheral nervous system?
Schwann cells
Which evidence supports the assertion that the macroscopic Na + current is the sum of many microscopic Na+ currents?
The averaged collective response of single channels resembles the time course of the macroscopic current
Cerebrospinal fluid is found where?
Ventricles and subarchnoid space (b and c)
The pia mater is :
a basement membrane (lamina) generated by astrocytes
What is the function of microtubules in a neuron?
all of the above
Which characteristic is an accepted criterion for classifying a molecule as a neurotransmitter?
all of the above
Which conclusion can be drawn from hodkin and Huxeleys studies of K+ and Na+ conductances?
all of the above
In the knee jerk reflex, the afferent neurons
are sensory neurons
Amphetamines cause release of
catecholamines and seotonin
Which of the following parts of a neuron would be labeled by a nissl stain?
cell body
Ion channels that are involved in generation of action potentials open or close in response to
changes in voltage
Which structure can be found exclusively at an electrical synapse?
connexon
studies of the ionic basis of the action potential in a squid giant axon found that
decreasing sodium outside of the cell decreases the size of the action potential
The amplitude of the action potential of a given neuron is
dependent on the magnitude of the sensory stimulus
An action potential occurs if current injected into a neuron ____ the neuron to reach _______ potential
depolarizes; threshold
In which order are catecholamine neurotransmitters synthesized?
dopamine, norepinephrine, epinephrine
which statement accurately describes the expression of genes in the nervous system?
every gene in the human genome is expressed in the CNS
In the sequence of events in neurotransmission, which event occurs just after the action potential arrives and spreads depolarization at the presynaptic terminal?
influx of Ca++ into the presynaptic terminal
Which statement best describes the Nernst equation
it relates the equilibrium potential of an ion to its intra- and extracellular concentrations
How will a neuron respond to an injection of negative current?
it will become hyperpolarized
Which vesicles, loaded with neuropeptides, arrive in the presynaptic terminal via axonal transport?
large dense core vesicles
The voltage clamp method controls the ________ at any desired level
membrane potential
which glial cell type serve as a resident immune cell in the central nervous system?
microglia
In general, the CNS of vertebrates has what type of organization?
motor functions are predominantly ventral, while sensory functions are dorsal
Which component represents the peripheral nervous system?
nerve
In the spinal cord, white matter is found on the ______ while gray matter is found on the _________
outside; inside
Which of the following best describes the thalmus?
part of the forebrain, a central relay station for motor and sensory info
Subthreshold current injected into an axon flows ______ along the axon and _______ with distance from the site of injection
passively; decays
Which experimental model did Hodgkin and Katz use in their studies of the resting membrane potential?
squid giant neuron
Which of the following best describes the neural doctorine?
the nervous system is made up of discreet individual cells
Which statement regarding refractory periods is true?
the refractory period sets an upper limit on the frequency of action potentials
Which processes underlies the refractory period?
the slow time course of turning off the K+ conductance activation and the persistence of sodium conductance inactivation
Which of the following is true regarding graded potentials?
their amplitude is proportional to the magnitude of the triggering stimulus
Which statement about astrocytes is true?
they play a role in the formation of the blood-brain barier
Which function is a characteristic primarily of neurons only, and not glia?
transmits action potentials
True or false: interneurons are found only in the CNS?
true
What is the common precursor of all catecholamines?
tyrosine
What are the causes of membrane potential?
unequal distribution of ions across the membrane, and a plasma membrane selectively permeable to some ions more than others
EPSPs are most often triggered by changes in conductance for ____________, while IPSPs are most often triggered by changes in conductance for ____________.
Na+ and Ca++; K+ and Cl-
Which transporter plays a key role in maintaining the concentration gradients of ions in the brain that are ciritical for generating electrical signals?
Na+/K+, ATPase pump
Concentrations of which ion, inside and outside of a neuron, have the greatest effect on the resting membrane potential ?
Potassium K+
