NeuroBio Final pt2 Cumulative
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...
+120 mV
Hodgkin and Katz discovered that the resting membrane potential changes by _______ mV per tenfold change in K+ concentration.
58 mV
From which part of the nervous system do cells that innervate neuromuscular junctions originate?
CNS
Driving force is the "push" on an ion and is determined by the difference between _________ and ________.
Cell voltage and ion equilibrium potential
What would occur if the ATPase pumps in a neuron stopped functioning?
Concentration gradients would not be maintained across the membrane
Which feature is the key characteristic of the pseudounipolar neurons of the somatosensory system?
Continuous fibers, with the cell body attached by a single process
On its way to the retina, light passes through tissues and fluids in which order?
Cornea, aqueous humor, lens, vitreous humor, retina
Tactile information from the face to the central nervous system follows which pathway?
Cutaneous receptors, cranial nerve V, trigeminal brainstem complex, VPM of thalamus, contralateral cortex
An action potential is an _________ change in the electrical potential across the nerve cell membrane
all-or-nothing
Referred pain
arises from the conveyance of both visceral and cutaneous pain information by dorsal horn neurons.
You record potentials from a Neuron C which receives input from two neurons, Neuron A and Neuron B. When both Neuron A and B are simultaneously stimulated, the potential you record from Neuron C is larger than the potential elicited from activation of either Neuron A or B alone. Which is a best description of this scenario?
both Neuron A and B form excitatory synapses and when stimulated simultaneously caused spatial summation of the postsynaptic response
Increased activity from the _______ to the subthalamic nucleus increases the _______ input to the VA/VL complex of the thalamus.
cerebral cortex; inhibitory
A loss of tactile, proprioceptive, pain, and temperature sensations localized to the lower right leg would most likely be the result of
damage of a right-side dorsal root ganglia
MPTP is a compound that
destroys the substantia nigra of monkeys (and humans).
What is true at cell resting potential?
driving force on sodium wants to push sodium INTO the cell
Mathematically, current can be calculated as _________ x ____________
driving force;conductance
As motor unit size increases, which property of the alpha motor neuron decreases?
Excitability
Which statement accurately describes neural and glial cells?
Exocytosis and endocytosis are important for synaptic communication.
What is the gate theory of pain?
Flow of ascending pain information is modified by stimulation of low-threshold mechanoreceptors.
The typical voltage-gated K+ channel is made up of _______, each of which contains helical membrane-spanning domains with a _______ between them.
Four protein subunits; pore loop
Which pathway represents a route that pain information could take in the nervous system?
Free nerve ending nociceptor, unmyelinated C fiber axon, spinal cord
What is the source of the quanta that make up the EPP?
Fusion of individual synaptic vesicles with the plasma membrane
Which equation calculates cell resting potential using permeabilities and ion concentrations for all of sodium, potassium, and chloride at the same time?
Goldman-Hodgkin-Katz equation
Which afferent fibers have the largest diameter?
Ia sensory afferents from the muscles
A dermatome is an area innervated by
fibers of the cells from a single dorsal root ganglion
In terms of conduction velocity, the axons arising from peripheral nociceptors
include the slowest-conducting of the peripheral sensory afferents
What is always true for ion movements?
ion movements push the cell toward that ion's equilibrium
"Spike-triggered averaging"
is a means of averaging out noise to better correlate spikes with muscle activation
During accommodation, the shape of the _______ is changed by the _______ in order to see objects accurately at varying distances.
lens; ciliary muscle and zonular fibers
D1 and D2 receptors are _______, with D1 receptors _______ cAMP and D2 receptors _______ cAMP.
metabotropic; increasing; decreasing
Two of the main functions of the retinal pigment epithelium are _______ and _______.
phagocytosis of shed outer segments; regeneration of the photoreceptor photopigments
A neuron that innervates (i.e., makes synaptic contact with) a large number of other neurons
represents divergent neural signalling
As a person squats, the quadriceps muscles contract. At the same time, the respective Golgi tendon organs _______ their firing rate, and the intrafusal muscle fibers _______ their firing rate.
Increase;decrease
In the sequence of events in neurotransmission, which event occurs just after the action potential arrives at the presynaptic terminal?
Influx of Ca into the presynaptic terminal
A ganglion cell's firing rate is proportional to what property of light?
Intensity
Which statement regarding metabotropic and ionotropic receptors is true?
Ionotropic receptors have immediate effects; metabotropic receptors act via secondary messenger pathways
The external segment of the globus pallidus projects to the internal segment and the _______ in the _______ pathway.
subthalamic nucleus; indirect
How would application of an intracellular Ca2+ chelator affect the function of a synapse?
It would reduce the number of vesicles released and so reduce postsynaptic responses
Which feature contributes to the superior acuity of the fovea?
Lack of retinal blood vessels
Which vesicles, loaded with neuropeptides, arrive in the presynaptic terminal via axonal transport?
Large dense-core vesicles
When the right cerebellum is damaged, which cortical region loses input (either directly or indirectly)?
Left motor cortex
Which of the following is a demyelinating disease of axons in the CNS?
MS
Which afferents have the highest spatial resolution?
Merkel afferents
Which glial cell type serves as a resident immune cell in the CNS?
Microglia
Which of the following pairs of proteins and inhibitors are both correctly matched?
voltage-gated sodium channel = TTX; voltage-gated potassium channel = TEA
The pathways that descend into the spinal cord and modulate pain transmission via direct influences on the dorsal horn arise from all areas except the
Periaqueductal gray
What is most accurate about placebos and pain?
Placebos may relieve pain by stimulating opioid signaling
What is the role of the vestibulocerebellum?
Posture
A monkey with damage to the ventral stream will have the most trouble with which task?
Recognizing a familiar face
Which treatment was shown to eliminate the early inward current in squid giant axons?
Removal of external sodium
According to the size principle, in which order are motor units recruited in response to increasing synaptic input?
S,FR,FF
Which is the voltage-sensor of a voltage-gated sodium channel?
S4
What is true of color vision?
The different photopigments in each cone are highly sensitive to a small range of wavelengths but can actually be activated by photons of a wide range of wavelengths. Information from specific color cones can be selectively relayed to specific regions of a retinal ganglion cell's receptive field. Different wavelengths of light produce different patterns of activity in the cone population as a whole. Cones (in humans) come in three different "colors": blue, green, and red (or short-, medium-, and long-wavelength).
How would you expect the somatosensory cortex in an adult who doesn't play an instrument to compare to that of an adult who has been playing piano since age 5?
The musician would have larger cortical representation of the fingers compared to the non-musician.
What is true about typical, resting neurons?
The permeability of the plasma membrane to potassium ions is much greater than its permeability to sodium ions.
Which property best differentiates the types of cones?
The photopigments they contain
How does the resting membrane potential of a typical neuron compare to the equilibrium potential (calculated by the Nernst equation) for potassium?
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.
Which of the following is not a function of the reticular formation?
Transmission of spinal nociceptive and tactile sensory signals to the cerebellum
Which function is a characteristic primarily of neurons only, and not glia?
Transmit action potentials
Which structure and division of the nervous system receives mechanosensory and proprioceptive information and relays it to the primary somatosensory cortex?
VPL of the thalamus
Which structure plays the largest role in the sensory-discriminative aspects of pain, as opposed to its affective aspects?
Ventral posterior lateral nucleus of the thalamus
Which structure contributes to the sensory-discriminative aspect of pain
Ventral posterior medial and lateral nuclei of the thalamus
Which event is the first in the series of events that take place during chemical synaptic transmission?
Voltage-gated Ca channels open
The voltage-clamp method holds _________ steady, while recording input of __________ to balance the __________ of the cell.
Voltage;current;current
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...
Would be equal in both directions
Which best describes the absolute refractory period?
a cell is incapable for initiating an action potential due to the inactivation of voltage-gated sodium channels
Ganglion cell axons cross at the _______, thus the _______ contains information from both eyes.
Optic chiasm; optic tract
Which technique would you use to study individual ion channel activities, without the effects of intracellular regulators?
Outside-out patch clamp
In what way are ion channels similar to active transporters?
Both are proteins
Which conclusion can be drawn from Hodgkin and Huxley's studies of K and Na conductances?
Both conductances depend on voltage Both conductances exhibit the property of time-dependent activation K+ conductance reaches its maximum with a pronounced delay Unlike K+ conductance, Na+ conductance reaches its max and inactivates rapidly
By which proposed molecular mechanism does Ca2+ promote fusion of synaptic vesicles?
By binding to synaptotagmin which pushes complexin out of the way and allows SNARE proteins to zipper
Which structure is responsible for input only to the cerebellum?
Middle cerebellar peduncle
Rapidly adapting fibers are most likely to provide information about the _______ of a stimulus.
Movement
The AMPA receptor primarily permits movement of _______ and _______, which typically results in a ________.
Na+; K+; synapse with several potential more positive than threshold
Which substance binds only at the extracellular domain of a ligand-gated ion channel?
Neurotransmitter
a cell is incapable for initiating an action potential due to the inactivation of voltage-gated sodium channels
Number of open ion channels specific for that ion
The _______ is inversely proportional to the density of the fibers supplying an area.
Size of the receptive field
Which is TRUE of voltage-gated channel kinetics underlying the action potential?
Sodium channels are faster to open than potassium channels
Which occurs during the depolarization phase of an action potential?
Sodium current exceeds that of potassium
Which of the following statements about directional tuning and population coding by primary motor cortical (PMC) neurons is correct?
The vector summation of population responses of PMC neurons is important for directional control of motor movements.
In voltage-clamp experiments, the early current of a cell will disappear when....
The voltage is set at the equilibrium potential for sodium
Which is true of GABA(A) receptors?
They are ionotropic receptors that form Cl- channels
Which role do γ motor neurons play in the function of a muscle spindle?
They improve the accuracy of the reported sensory information by innervating intrafusal fibers.
