Kines 360 Exam 1 HW Questions

At which point during signal transmission at a chemical synapse is exocytosis occurring?

During neurotransmitter release into the synaptic cleft

Which statement regarding membrane potential and equilibrium potential is true?

Equilibrium potential is affected by the concentration and electrical gradients of one ion; membrane potential is affected by gradients of all ions

The primary sensory or motor function of each lobe is (match the correct response):

Frontal - motor and cognition parietal - somatosensory occipital. - vision temporal - auditory

What is the main excitatory neurotransmitter in the adult brain?

Glutamate

Which property is characteristic of Na+ channels but not K+ channels?

Inability to inactivate slowly

The refractory period can be considered to operate using activation and inactivation gates. Repolarization (change in membrane potential that returns it to a negative value) of membrane potential begins about 1 msec after the activation gate opens. What happens next? NO CORRECTNESS POINTS.

Inactivation gate closes to stop the passage of sodium ions

In the sequence of events in neurotransmission, which event occurs just after the action potential arrives at the presynaptic terminal?

Influx of Ca2+ into the presynaptic terminal

The figure shows an electron micrograph of a chemical synapse in the cerebral cortex. Which statement about this synapse is accurate? NO CORRECTNESS POINTS.

Inside the presynaptic neuron are synaptic vesicles, which fuse with the membrane in the active zone

Which statement regarding metabotropic and ionotropic receptors is true?

Ionotropic receptors have immediate effects; metabotropic receptors produce long-term effects

What is the action of the neurotransmitter at a chemical synapse?

It acts on receptors in the postsynaptic membrane.

Which statement best describes the function of a neuron with multiple, highly branched dendrites and one axon?

It integrates information from many neurons

Which statement about Na+ permeability during an action potential is most accurate?

It is responsible for the rising phase of the action potential.

Which statement about electrochemical equilibrium is true?

It occurs when the potential across the membrane exactly offsets the concentration gradient

How will a neuron respond to an injection of negative current?

It will become hyperpolarized

Concentrations of which ion, inside and outside of a neuron, have the greatest effect on the resting membrane potential?

K+

Which layer of the neuron in the cerebrum receives sensory signals from the thalamus? Click on the figure.

Layer IV

The major arterial supply to the frontal, parietal, and temporal cortical regions that areimportant for motor control and speech is derived from the ___

Middle cerebral artery

Which statement about myelination is FALSE?

Myelin serves to sharply decrease the conduction of action potentials

Which statement about voltage-gated ion channels is true?

Na+ and K+ channels can work independently of one another

In which of the following cases is the ionic current going to be the maximum?

No of open ion channels=100; driving force = 50 mV

How does membrane permeability to K+ (PK) and Na+ (PNa) change during an action potential?

PK exceeds PNa at rest; PNa temporarily increases during the action potential

A Na+/K+ ATPase pump is responsible for maintaining concentration gradients for both Na+ and K+ ions. Which intervention will disrupt the function of the Na+/K+ ATPase pump?

Removal of extracellular K+

Watch the video on Canvas for Lesson 2b and answer the following question. During which phase of an action potential does membrane permeability to Na+ exceed membrane permeability to K+? NO CORRECTNESS POINTS.

Rising and overshoot phases

The resting membrane potential typically ranges from ___ to ___.

-40 mV; -90 mV

Calculate the equilibrium potential for at room temperature. Use the formula shown below. The charge on a sodium ion, z=1. Assume that (RT/zF)=25.7. mM is the extracellular concentration and mM is the intracellular concentration.

-59 mV

Calculate the membrane potential. Use the formula shown below. Assume that the permeability of chloride ions is zero.(RT/zF)=25.7. mM is the extracellular concentration of mM is the intracellular concentration of is the permeability of mM is the extracellular concentration of mM is the intracellular concentration of is the permeability of

-63 mV

How many layers are there in the cerebral cortex?

6

Which change could be responsible for increasing the amplitude of an excitatory postsynaptic potential (EPSP)?

An increase in the amount of glutamate released into the synapse

Which feature of an electrical synapse allows synchronizing the electrical activity of multiple neurons?

Bidirectional transmission of electrical signals

In the class we talked about pain perception and Na+ ion channels. Read the textbook and answer the following question. What is the mechanism of action of most local anesthetics? NO CORRECTNESS POINTS.

Block Na+ channels involved in the generation of action potentials

In what way are GABA and glutamate similar in the adult brain?

Both are common in the nervous system

Cell X fires an action potential and releases GABA onto Cell Y. Assuming only GABAA receptors are present on the postsynaptic membrane, which is at rest at -55mV, which ion is responsible for the changes that would be observed?

Chloride

When a GABAA ionotropic receptor is stimulated by GABA , which ions flow through its channel, and what effect does this have on the postsynaptic cell?

Cl-, which hyperpolarizes the postsynaptic cell

Which one is not a main function of the glial cells?

Communicate neural information across brain areas via chemical and electrical signalling

Which structure can be found exclusively at an electrical synapse?

Connexon

To which category of neurotransmitters does acetylcholine belong?

Small-molecule neurotransmitters

Which statement correctly differentiates between the passive and active current in a myelinated axon?

The active current flows only in the nodes of Ranvier, unlike the passive current

Which statement does the graph illustrate?

The behavior of Na+ channels is voltage dependent

Which of the following is the key event when the membrane potential is depolarized to 0 mV? Refer to the figure below.

The early inward current is at its maximum

Which consequence of Na+ channels staying open, instead of closing after membrane depolarization, is most plausible?

The membrane would not repolarize (return to a negative value of membrane potential) following depolarization

Which statement regarding refractory periods is true?

The refractory period ends when the sodium channels are no longer inactivated

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 current corresponds to a flow of Na+ in response to a depolarizing stimulus in a giant axon of a squid?

Transient inward current

Which feature do the three transporters shown in the figure share? NO CORRECTNESS POINTS.

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

Which event is the first in the series of events that take place during chemical synaptic transmission?

Voltage-gated Ca2+ channels open

Which characteristic is an accepted criterion for classifying a molecule as a neurotransmitter?

a It must be present in the presynaptic terminal b It must be released in response to presynaptic electrical activity c It must exert an effect on the postsynaptic cell

Ion channels

a allow ions to move across the membrane quickly b work with the electrochemical gradients to pass ions c exist in distinct variants, allowing different types of ions to pass d respond to changes in the membrane potential e All of the above

The three cardinal spatial planes through the brain are (select ALL correct answers)

a Transverse/Horizontal/Axial b Coronal/Frontal c Sagittal

Which property(ies) of the action potential do the graphs in the figure illustrate? There could be multiple correct answers. Pick at least one. NO CORRECTNESS POINTS.

aRefractoriness bAll-or-none dPolarized propagation

Which of the following is the key event when the membrane potential is depolarized from 26 mV to 52 mV? Refer to the figure below.

aThe late outward current increases in magnitude cThe early inward current reverses its polarity

Which statements about EPSPs in the central nervous system are true? SELECT ALL CORRECT ANSWERS. NO CORRECTNESS POINTS.

aThey are more positive than resting potentials dTheir effect in the central nervous system can be nullified by IPSPs

Which conclusion can be drawn from the studies of K+ and Na+ conductances?

all of the above

The amplitude of the action potential of a given neuron is

always the same

Relative to the forebrain neuraxis, a rostral location is more _ than a caudal location.

anterior

The myelin sheath is an extended and modified plasma membrane that facilitates nerve conduction. Where is it located? Click on the figure.

axon

The resting potential of a cell is negative because (SELECT ALL CORRECT OPTIONS)

c. at rest there is an excess of K+ inside the cell, and the membrane is permeable chiefly to K+. e many of the molecules needed for life - nucleic acids, amino acids, and proteins - are negatively charged molecules or anions. Most of these are too large to leave the cell.

Which movement disorder is associated with deficits in the basal ganglia? Select ALL CORRECT ANSWERS.

cHuntington's disease dParkinson's Disease

In a two-compartment model of a cell with a K+-permeable membrane and a 10-fold excess of K+ in the inside compartment, how would the membrane potential change if all K+ ions were replaced by Na+ ions?

cIt would not change eNo potential would be generated

Which of the neurons below have the highest degree of convergence? Click on the picture below.

cerebellar purkinje cell

Which neural region does not belong in the forebrain?

cerebellum

Which of the following does not belong to the midbrain?

cerebellum

The large white matter tract that connects the two hemispheres is the ___

corpus callosum

Which cranial nerves enter the forebrain directly? SELECT ALL CORRECT ANSWERS.

dOptic nerve eOlfactory nerve

Studies of the ionic basis of the action potential has shown that

decreasing sodium outside the cell decreases the size of the action potential

Studies of the ionic basis of the action potential in squid giant axon found that

decreasing sodium outside the cell decreases the size of the action potential

Presynaptic and postsynaptic neurons that form ___ synapses are connected via ___.

electrical; gap junctions

The capability of a nerve terminal to rapidly and dramatically produce very large changes in calcium levels is most dependent on the

enormous gradient of calcium across the membrane

During the knee jerk reflex, the role of the spinal interneuron is to ___ the ___ muscle, allowing the leg to ___.

inhibit; flexor; extend

The cerebral ventricular system is made up of 4 ventricles that include two lateral ventricles in the cerebrum, the third ventricle in the diencephalon, and the fourth ventricle in the hindbrain. Which area is NOT a part of the hindbrain?

insula

Which glial cell type serves as a resident immune cell in the central nervous system?

microglia

The insular cortex (insula) is hidden beneath the frontal and temporal lobes. Which one of the following is not a main function of the insula?

motor control and complex cognition

The spinal cord does not play an important role in __

movement planning

In a two-compartment model of a cell with a K+-permeable membrane, at K+ equilibrium potential, there is ___ flux of K+ ions.

no net

In the phase labeled B, the voltage-gated sodium channels are ____ and the voltage-gated potassium channels are ____.

open ; closed

Which cranial nerve is actually a part of the diencephalon?

optic nerve

Which of the following nerves is NOT involved in eye movements?

optic nerve (II) and Trigeminal nerve (V)

The parieto-occipital sulcus is a very deep sulcus that crosses the posterior part of the hemisphere and divides the internal occipital lobe from the _ lobes

parietal

Which meningeal layer is located closest to the brain?

pia mater

Decussation is the point in the central nervous system at which a major ascending sensory pathway crosses the midline. Where in the brainstem do most of the ascending fibers typically cross the midline? SELECT ANY CORRECT ANSWER.

pons and medulla

Relative to the spinal neuraxis, dorsal refers to __, while ventral refers to ____.

posterior, anterior

An action potential travels in only one direction along the axon because of its ___ property.

refractory

A neuron that innervates (i.e., makes synaptic contact with) a large number of other neurons

represents divergent neural signaling

In the figure below, the relationship between resting membrane potential and external concentration of K+ is shown. The straight black line represents a slope of 58 mV per ten-fold change in concentration of K+ in extracellular space. Why is that different from the red line observed in real experiments conducted with giant squid axons?

resting membrane potential depends on multiple ions

Watch the video uploaded on Canvas for Lesson 2b and answer the following question. Which state of the plasma membrane does not occur during an action potential?

resting phase

Which of the following neurons has the lowest divergence? Click on the neuron below.

retinal amacrine cell

In the phase labeled B, ___ ions are moving ___ the cell.

sodium ; into

The area shown in blue is just caudal to the central sulcus. Which area of the brain is this?

somatosensory cortex

Relative to the spinal neuraxis, a rostral location is more___ than a caudal location.

superior

Relative to the forebrain neuraxis, dorsal refers to ___, while ventral refers to ___.

superior, inferior

Gap junctions may exhibit all of the following features except

the ability to amplify small incoming electrical signals into large regenerative potentials

Which function is a characteristic primarily of neurons only, and not glia?

transmits action potentials

The internal capsule has white mater tracts that connect the thalamus with the cerebral cortex. In addition, the internal capsule has axons which descend from the cortex to the brain stem.

true

Ion channels that are involved in generation of action potentials open or close in response to

voltage

What is the main cause of myasthenia gravis symptoms?

Autoimmune reaction against nicotinic acetylcholine receptors

Which process(es) underlie(s) the refractory period?

The slow time course of turning off K+ conductance activation and the persistence of Na+ conductance inactivation

Which statement about active ion transporters is true?

They move certain ions against the concentration gradient