Kines 360 - Exam 1 Tophat

What is the main excitatory neurotransmitter in the adult brain?

Glutamate

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 electrochemical equilibrium is true?

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

Which meningeal layer is located closest to the brain?

Pia mater

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+

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

Which state of the plasma membrane does not occur during an action potential?

Resting phase

During which phase of an action potential does membrane permeability to Na+ exceed membrane permeability to K+?

Rising and overshoot phases

There are ______ neuraxes through the nervous system

2

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

Both are common in the nervous system

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

Bottom right

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

Corpus callosum

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

Somatosensory cortex

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

Voltage-gated Ca2+ channels open

Where is the cerebellum in the brain? Click on the figure.

arrow pointing

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

layer 4

The resting potential of a cell is negative because

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.

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

superior, inferior

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

voltage

Nernst potential for ions is 100+ mV, much more depolarized than the peak of the action potential. This means that

when channels open, ions will enter the cell with great driving force

Which statement regarding refractory periods is true?

when the sodium channels are no longer inactivated

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

- Transverse/Horizontal/ Axial - Coronal/Frontal - Sagittal

The resting membrane potential typically ranges from _______ to _______.

-40 mV; -90 mV

Calculate the membrane potential. Use the formula shown below. Assume that the permeability of chloride ions is zero. (RT/zF)=25.7. NO CORRECTNESS POINTS 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

-55 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

Based on the figure 3.2 in the texbook, what is the equilibrium potential of the Na+ ion?

55 mV

Based on this figure, what is the equilibrium potential of the Na+ ion in the recorded cell. Use the Ohm's equation to answer this question. Iion= g ×(Vm - Eion), where Vm is the membrane potential and Eion is the equilibrium potential (in this case for Na+).

55 mV

How many layers are there in the cerebral cortex?

6

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

60 mV

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

All of the above

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 d None of the above

All of the above

Which conclusion can be drawn from the studies of K+ and Na+ conductances? a Both conductances exhibit the property of time-dependent activation b Both conductances depend on voltage c K+ conductance reaches its maximum with a pronounced delay d Unlike K+ conductance, Na+ conductance reaches its maximum and inactivates rapidly

All of the above

Which property(ies) of the action potential do the graphs in the figure illustrate? There could be multiple correct answers. Pick at least one.

All-or-none

The picture below shows three neurons. Which one of these neurons is receiving the maximum input from other neurons (hint: large dendritic tree)?

B

What is the mechanism of action of most local anesthetics?

Block Na+ channels involved in the generation of action potentials

In what way are ion channels similar to active transporters?

Both actively move ions from one side of the membrane to the other.

Which of the following does not belong to the midbrain?

Cerebellum

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 signaling

What is the major determinant of the permeability/conductance of a membrane to a specific ion?

Concentration of the ion inside the cell

Which structure can be found exclusively at an electrical synapse?

Connexon

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

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

Far left

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

Frontal matches Motor and cognition Parietal matches Somatosensory Occipital matches Vision Temporal matches Auditory

If depolarization of a cell, causes many Na+ and K+ ion channels to open. Based on Ohm's Law, does the cell resistance go up or down?

Goes down

The thalamus is a paired gray matter structure of the diencephalon located near the center of the brain and is acts as a relay station filtering information between the brain and body. Based on what we discussed earlier, which layer of the cortex would the thalamus primarily send output to and which layer of the motor cortex would subcortical structures mainly receive inputs from?

IV, V

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.

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?

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

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

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

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

It will become hyperpolarized

How will a neuron respond if an experimenter injects negative current into the intracellular space? (injection of -ve current is the same as outward +ive current)

It will become hyperpolarized.

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?

It would not change

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

K+

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

Microglia

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

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

The spinal cord does not play an important role in ______

Movement planning

Which statement about myelination is FALSE?

Myelin serves to sharply decrease the conduction of action potentials

With the release of a neurotransmitter (say acetylcholine), N number of channels opened. In which case is the membrane conductance the lowest?

N=300

Current flow is given by Ohm's Law, , where is ion conductance and is the driving force. If the driving force is 30 mV, in which case is the current flow going to be maximum? N implies no of open channels.

N=600

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

Which cranial nerve is actually a part of the diencephalon?

Optic nerve

Which cranial nerves enter the forebrain directly?

Optic nerve Olfactory nerve

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

Optic nerve (II)

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

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 part of the brain is involved in integrating sensory information from different parts of the body and between different sensory modalities?

Parietal

Which movement disorder is associated with deficits in the basal ganglia?

Parkinson's Disease Huntington's disease

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?

Pons

To which category of neurotransmitters does acetylcholine belong?

Small-molecule neurotransmitters

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

Superior

Which region of the brain would be involved in planning and execution of complex movements, such as a basketball free throw?

Telencephalon

For which part of the brain would you use the long axis of the forebrain?

Telencephalon and diencephalon

Except for the olfactory nerve (I) and the optic nerve (II), almost all the cranial nerves emerge from the brainstem. Where do these two nerves derive from (olfactory first)?

Telencephalon, diencephalon

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

The early inward current reverses its polarity

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

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

Nodes of Ranvier represent

gaps in myelin wrapping

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

inhibit; flexor; extend

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

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 phase labeled B, _______ ions are moving _______ the cell.

sodium; into

Gap junctions may exhibit all of the following features except

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

Why is the white matter lighter than the gray matter?

White matter is richer in myelin, which reflects more light than gray matter.

The proteins that establish ionic gradients are called

active transporters

The amplitude of the action potential of a given neuron is

always the same

Which neural region does not belong in the forebrain?

cerebellum

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

An action potential occurs if current injected into a neuron _______ the neuron to reach _______ potential.

depolarizes; threshold

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

Transmits action potentials

Which feature do the three transporters shown in the figure share?

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

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

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

Anterior

What is the main cause of myasthenia gravis symptoms?

Autoimmune reaction against nicotinic acetylcholine receptors

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

Axon

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 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 statements about EPSPs in the central nervous system are true?

Their effect in the central nervous system can be nullified by IPSPs

Which statement about active ion transporters is true?

They move certain ions against the concentration gradient

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

Transient inward current