Neurobiology Test 1

The Goldman-Hodgkin-Katz equation is useful for calculations involving multiple ions

True

The Nernst equation is useful for calculations involving a single ion

True

The long term impact of a stroke depends upon the location of the stroke in the brain

True

the activation of one metabotropic receptor can result in the activation of many internal signal transduction pathway molecules, an example of signal amplification

True

the general rule of postsynaptic action is: if the reversal potential is more positive than threshold, excitation results, inhibition occurs if the reversal potential is more negative than threshold.

True

the nernst equation assumes selective permeability to one type of ion

True

which of the following statements regarding this figure of an axon are true

- passive current flow is moving in both directions, but an action potential is unidirectional because of voltage gated sodium channel inactivation - action potential conduction can be increased by either increasing the presence of myelin or by increasing the size of the Exxon - the figured depicts an Exxon experiencing an action potential, indicated by arrows indicating current flow - an action potential is a regenerative, high fidelity event that replicates itself over and over along the length of the axon

Consider a newly discovered creature whose neurons function according to the same principles that squid and human neurons do. The following ionic concentration ratios are known: Ion 1 (A+) Outside: 100 Inside: 1 Ion 2 (B+) Outside 1: Inside 10 If the cell membrane were selectively permeable to ion 1 (A+) at rest, what would the resting membrane potential be?

+122 mV

which of the following statements are true regarding GABA receptors

- GABA sis a natural neurotransmitter that activates the GABA receptor - Glia can manipulate GABA receptor activation by producing neurosteroids

Which of the following are true statements about neurotransmitter receptors

- Ionotropic neurotransmitter receptors are composed of multiple subunit proteins that contain a channel to allow ion passage - metabotropic and ionotropic receptors can be activated by the same neurotransmitter - metabotropic receptors act more slowly than ionotropic receptors

Which of the following are true statements regarding nodes of ranvier

- The justaoaranodal region is enriched with voltage-gated potassium channels -loss of myelin and the disintegration of the nodes of ranvier are a chief cause of multiple sclerosis - the node region is enriched with voltage-gated sodium channels - the nodes tend to be 1-2 mm apart along an axon

Which of the following are true statements regarding glia

- They can direct localization of ion channels - Astrocytes play an important role in regulating extracellular K+ concentrations - glial cells can uptake neurotransmitters

Which of the following are true statements about electrical synapses

- They can directly and bidirectionally exchange ions between neurons - Structurally, they include gap junctions made of connexion proteins

Which of the following statements are true of myelin

- a loss of myelin could cause failures of action potentials to travel all the way to the axon terminal - a loss of myelin could result in a decrease in action potential conduction speed

Which of the following are true statements regarding potentials

- an equilibrium potential is specific for one ion, and can be calculating using the nernst equation - the threshold potential as the potential at which an action potential is initiated - the reversal potential is for a synapse, and may or may not be the same as an equilibrium potential. - the resting membrane potential is a neuron's potential when an action potential is not occurring, And is determined by the neuron's ionic permeability

Which of the following could result in an increase in neurotransmitter release by a presynaptic neuron

- and application of a drug such as TEA that blocks voltage could a potassium channels - Application of low concentrations of a drug such as Nefiracetam that acts as an agonist on voltage-gated calcium ion channels - Addition of synaptotagmin proteins in the presynaptic terminal

Synaptic integration

- can involve both excitatory and inhibitory synaptic inputs - can involve both spatial and temporal summation - depends in part on the length constant of the dendrites involved

which of the following are accurate means by which a chemical synapse may be altered to change its function

- increasing the number of glutamate transporters - activation of NMDA receptors - decreasing the number of AMPA receptors

Which of the following statements regarding extracellular potassium concentration around neurons is true

- it is lower than the intracellular potassium concentration - an abnormal increase in extracellular K+ levels could depolarize the neuron

Several mechanisms mediate the equilibrium potential. Which of the following are false statements about these mechanisms

- the equilibrium potential for a particular ion is determined only by the chemical driving forces on that ion - decreases in extracellular concentration of an ion will not change its equilibrium potential

You are studying a synapse in the mammalian striatum for your first project in graduate school. During your studies, you make the following observations: - you can mimic the effect of presynaptic stimulation by applying muscarine - the effects of muscarine occur slowly - you can block the post synaptic potential using atropine, but curare has no effect which of the following would you conclude to be true at this synapse

- the neurotransmitter binds to a ligand-gated neurotransmitter receptor - the synaptic cleft contains acetylcholinesterase - the receptor acts on a monomeric receptor - the neurotransmitter is acetylcholine (ACh)

which of the following statements are true regarding this graph

- the post synaptic potential was recorded in current clamp - the post synaptic potential is depolarizing because chloride ions are leaving the neuron - the theoretical maximum depolarization effect of these synapses is the equilibrium potential for chloride

Neuroscience involves the study of many different types of potentials. which of these statements regarding potentials are true

- the resting membrane potential of a neuron is determined by the permeability of that neuron to ions, including potassium and sodium - a reversal potential is the membrane potential of a postsynaptic neuron for other target cell at which the action of a given neurotransmitter causes no net current flow - a threshold potential is the point at which current from voltage gated sodium channels overcomes the current from leak potassium channels - a reversal potential can be the same as an equilibrium potential

You are studying a type of neuron in which the resting membrane potential (RMP) changes with the time of day as described here. RMP = -90 mV in the morning RMP = -70 mV in the afternoon RMP = -60 mV in the evening RMP = -50 in the middle of the night During each experiment, you apply the same amount of your transmitter Z and measure its effect on membrane potential, getting the following results in mV What is the reversal potential for the synapse activated by neurotransmitter Z?

-60 mV

Figure A shows a typical action potential. Figures B-D show the results of chemically altering the action potential using different agents separately. In each case, the cell is directly stimulated to threshold just 5 msec after the treatment has taken effect (so we are not considering long-term effects), the membrane potential is recorded 1. if you treat the neuron with 10 M TEA, which blocks voltage-gated potassium channels, which would you expect the action potential in that neuron to look 2. if you treat a neuron with Ouabain, which blocks sodium-potassium ion pump function, what would you expect the action potential in that neuron to look like 3. If you treat the neuron with TTX, what would expect the action potential in that neuron to look like

1. B 2. A 3. None

You are studying a glutametergic Chemical synapse. You find that the presynaptic neuron is not experiencing an action potential. You measure that the postsynaptic neuron is hyperpolarized to -60 mV. 1. is there a lot of glutamate in the synaptic cleft or a little 2. is the glutamate transporter transporting. a lot of glutamate or a little

1. a little 2. a little

Damage in (1) in the (2) lobe gives raise to a deficit in the production of language, whereas damage in (3) in the (4) lobe results in a deficit in comprehension. this is a clear example of different regions of the brain being involved in different functions, even though both participate in language

1. broca's area 2. frontal 3. wernicke's area 4. temporal

You are studying a glutametergic Chemical synapse. You find that the presynaptic neuron is not experiencing an action potential. You measure that the postsynaptic neuron is hyperpolarized to -60 mV. 1. are NMDA glutamate receptors on the postsynaptic side open or closed 2. are AMPA glutamate receptors on the postsynaptic side open or closed

1. closed 2. closed

You are studying a glutametergic Chemical synapse. You find that the presynaptic neuron is not experiencing an action potential. You measure that the postsynaptic neuron is hyperpolarized to -60 mV. 1. are voltage-gated calcium channels on the presynaptic neuron open or closed 2. are voltage-gated sodium channels on the presynaptic neuron open or closed

1. closed 2. closed

Here is a hypothetical circuit involving three neurons. Each neuron makes a GABAergic synapse on its neighbor. For each of the following manipulations, indicate whether you would expect each manipulation to be more likely to have an excitatory, inhibitory, or no effect on neuron C: 1. Increased extracellular K+ concentration surrounding neuron B 2. Neuron A is exposed to a voltage-gated calcium channel antagonist 3. opening voltage-gated sodium channels on the dendrites of neuron B 4. The action potential threshold of neuron A becomes hyperpolarized 5. Increased action potential generation in neuron A

1. inhibitory 2. Inhibitory 3. Inhibitory 4. Excitatory 5. Excitatory

You are studying a synapse in the mammalian striatum for your first project in graduate school. During your studies, you make the following observations: - you can mimic the effect of presynaptic stimulation by applying muscarine - the effects of muscarine occur slowly - you can block the post synaptic potential using atropine, but curare has no effect 1. for your next experiment you expose the synapse to parathion, an acetylcholinesterase inhibitor, for 1 hour. you then stimulate the presynaptic neuron. what is you hypothesized effect on the post synaptic response 2. if you expose the synapse to AMPA for one hour, and then stimulate the presynaptic neuron, what would the hypothesized effect be on the post synaptic response

1. larger 2. same size

You are studying an electrical synapse which allows for the following ions to flow: potassium, and sodium. You find that the presynaptic neuron is experiencing an action potential. You measure that the postsynaptic neuron is depolarized and -30 mV. What would you hypothesize about the following components of this synapse 1. is glutamate likely flowing across the synapse 2. are sodium ions likely flowing across the synapse

1. no 2. no

You are studying a glutametergic Chemical synapse. You find that the presynaptic neuron is not experiencing an action potential. You measure that the postsynaptic neuron is hyperpolarized to -60 mV. 1. are snare proteins widely activated to deliver vesicles to the membrane or not 2. are synaptotagin proteins activated or not

1. not activated 2. not activated

You are studying myelin in the Central nervous system and make the micrograph shown here 1. what type of glia is responsible for the myelination of these axons 2. in diseases such as multiple sclerosis, demyelination occurs. when myelin degrades, how does this impact the speed of action potential propagation

1. oligodendrocyte 2. decreases

You are studying an electrical synapse which allows for the following ions to flow: potassium, and sodium. You find that the presynaptic neuron is experiencing an action potential. You measure that the postsynaptic neuron is depolarized and -30 mV. What would you hypothesize about the following components of this synapse 1. are connexin protein open or closed 2. are the changes in membrane potential in the presynaptic neuron quickly or slowly communicated to the postsynaptic neuron

1. open 2. quickly

You depolarize a neuron to +30 mV and hold the membrane at the potential. threshold potential for this neuron is -50 mV. What you record is shown here, with current plotted (y-axis) against time (x-axis) 1. Which island would you hypothesize is causing the change in current at letter C 2. Is the current at letter C following inward or outward 3. At letter A, which ion would you predict to have a larger conductance 4. would you hypothesize that these currents are the result of the activity of two individual ion channels or the summed activity of many hundreds of ion channels

1. potassium 2. Outward 3. Sodium 4. Many ion channels

The figure below shows a schematic of the neuron with three synapses (labeled A, B, and C), and a recording site located on the axon hillock. The resting membrane potential of the neuron is -60 mV, and threshold is -50 mV. 1. What type of summation is a high-frequency stimulation only synaptic input C 2. Following a single stimulation of synaptic input A, you record a 10 mV depolarization at the recording site. What would you hypothesize will occur 3. Now consider simultaneous activation of synaptic inputs B and C. Is synaptic input C allows chloride ion entry and has a reversal potential of -65 mV, what would you hypothesize will occur

1. temporal 2. action potential 3. no action potential

You are studying a type of neuron in which the resting membrane potential (RMP) changes with the time of day as described here. RMP = -90 mV in the morning RMP = -70 mV in the afternoon RMP = -60 mV in the evening RMP = -50 in the middle of the night During each experiment, you apply the same amount of your transmitter Z and measure its effect on membrane potential, getting the following results in mV Which of the following is a better explanation of the reversal potential

At the reversal potential channels are open there is no net movement of ions across the plasma membrane

Ion 2 (B+) has a higher concentration inside the neuron compared to the extracellular fluid. to determine which ion contributes to the resting membrane potential, you experimentally increase the concentration gradient of B+ by doubling its concentration in the extracellular fluid. To complete this experiment, what type of patch clamp should you use

Current clamp

You are studying a type of neuron in which the resting membrane potential (RMP) changes with the time of day as described here. RMP = -90 mV in the morning RMP = -70 mV in the afternoon RMP = -60 mV in the evening RMP = -50 in the middle of the night During each experiment, you apply the same amount of your transmitter Z and measure its effect on membrane potential, getting the following results in mV In the morning, does neurotransmitter Z cause depolarization or hyperpolerization of these neurons

Depolarization

What type of micrograph is this

Electron

A receptor agonist binds to a receptor and blocks the normal action of a ligand, including neurotransmitters

False

An afferent neuron carries information away from a neural circuit

False

IPSPs always cause hyperpolerization of the postsynaptic membrane

False

In a neuron that has lost its myelin, you would expect to see an increase in the length constant (lambda)

False

Ion Channels require energy to function

False

Leak ion channels are closed during an action potential

False

Sodium-potassium pumps drive the afterhyperpolarization of the action potential

False

The activation of one inotropic receptor can result in the activation of many ion channels, an example of signal amplification

False

Threshold is reached whenever a neuron is depolarized enough to close voltage-gated potassium channels

False

at rest, the open ion channels in the membrane of a neuron are primarily voltage-gated potassium channels

False

the equilibrium potential for a given ion is the membrane potential at which the ionic concentration inside the cell is equal to the concentration outside the cell

False

the rate limiting step in the synthesis of dopamine is the availability of the precursor tyrosine

False

GABA ion channel receptors allow calcium ions to enter the neuron

False (chloride)

The phenotype of multiple sclerosis can differ widely from person to person and even over the course of disease. Which of the below is a fundamental property of the mammalian central nervous system that helps explain the variable phenotype of MS

Localization of function

You are studying a type of neuron in which the resting membrane potential (RMP) changes with the time of day as described here. RMP = -90 mV in the morning RMP = -70 mV in the afternoon RMP = -60 mV in the evening RMP = -50 in the middle of the night During each experiment, you apply the same amount of your transmitter Z and measure its effect on membrane potential, getting the following results in mV If the threshold for these neurons is at -50mV is neurotransmitter Z excitatory or inhibitory when applied to these neurons

Inhibitory

Stroke is due to blockage of the cerebral blood supply, not a blow-out

Ischemic

Consider a newly discovered creature whose neurons function according to the same principles that squid and human neurons do. The following ionic concentration ratios are known: Ion 1 (A+) Outside: 100 Inside: 1 Ion 2 (B+) Outside 1: Inside 10 When you measure the cell membrane potential, you find that it is -60 mV At this point, is the memory more permeable to ion 1 (A+), ion 2 (B+), or neither?

It is more permeable to ion 2 (B+). The reason why is that the Eion for B+ is very negative. The resting membrane potential directly relates to what ion channels are open at rest. Since the resting membrane potential is -60 mV, that is much closer to Eion of B+

How does this (electron) micrograph support Cajal's neuron doctrine

It shows the existence of the synaptic cleft. This indicates that the central nervous system is composed of individual neurons, not one giant reticulum

You are studying a synapse in the mammalian striatum for your first project in graduate school. During your studies, you make the following observations: - you can mimic the effect of presynaptic stimulation by applying muscarine - the effects of muscarine occur slowly - you can block the post synaptic potential using atropine, but curare has no effect which neurotransmitter receptor type would you conclude mediates this synapse

Metabotropic

A patient presents herself with fluent, ebullient speech. However, the patient exhibits poor comprehension of verbal tests and what speech there is appears inappropriate. You hypothesize that this condition reflects a stroke of a brain artery. Which one

Middle Cerebral artery

Which type of glia are more likely to be involved in the demyelination characteristic of multiple sclerosis

Oligodendrocytes

For the image above (electron micrograph of neuron) what evidence can be used to identify presynaptic neuron

The presence of presynaptic vesicles

you are recording a neuron using whole-cell patch clamp in current clamp configuration. at the time indicated in the above graph, you activate synapses that open chloride (Cl-) channels. how will the voltage of the membrane react to the activation of these synapses

There will be no net change AND the membrane will depolarize DEPENDING ON GRAPH SHOWN

Acetylcholine effects on muscle fibers are mediated by the ionotropic nicotinic acetylcholine receptors (nAChR)

True

Hemorrhagic stroke is due to a rupture in blood vessel

True

Metabotropic receptors are G-protein coupled receptors

True

Metabotropic receptors are linked to G proteins which stimulate signal transduction pathways

True

Mitochondria can be characterized as generators of energy used by the presynaptic terminal, AKA the mitochondria are the POWERHOUSE of the neuron

True

NMDA receptors are glutamate receptors that are gated both by glutamate, glycine, and by voltage, and are composed of multiple subunits

True

Neuromodulatory synapses can alter the response of a postsynaptic neuron to other synaptic inputs by closing potassium channels

True

Neuropeptides that act as neurotransmitters typically are synthesized in the cell body and sent to the terminal by anterograde transport along microtubules

True

Neurotransmitter action is dependent upon the type of Neurotransmitter receptors expressed by the postsynaptic cell

True

Stroke cases helped establish localization of function as a basis for modern neuroscience

True

Synaptotagmins can be the calcium sensor necessary for vesicular fusion

True

A patient presents herself with fluent, ebullient speech. However, the patient exhibits poor comprehension of verbal tests and what speech there is appears inappropriate. Which aphasia would you classify this case as

Wernicke's aphasia

Others electrically-excitable cells function in a similar matter to neurons, with regulation of membrane permeability being critical to the membrane potential. The details, however, vary depending on the specific ion channels expressed by any given cell type. Pacemaker cells in the heart express voltage-gated calcium channels (opened by depolarization) that act like the voltage-gated sodium channels we have discussed in neurons - specifically, the rising phase of their action potential is driven by calcium movement across the membrane. Leak and voltage-gated potassium channels are also expressed and operate just as they do in the neurons we have been discussing. These pacemaker cells also expressed voltage-gated sodium channels (HCN channels) that open in response to hyperpolarization - related to the voltage-gated sodium channels we discussed, but with the obvious differences in their gating properties. The result is regular, spontaneous action potentials, as shown above (with membrane potential plotted against time). How could you regulate these pacemaker cells to increase or decrease action potential generation rate?

You could increase the number of HCN channels. Increasing the number of HCN channels would increase action potential generation.

Which of the following could result in a decrease in neurotransmitter release by a presynaptic neuron

a decrease in extracellular calcium levels outside the presynaptic terminal

You are studying a type of neuron in which the resting membrane potential (RMP) changes with the time of day as described here. RMP = -90 mV in the morning RMP = -70 mV in the afternoon RMP = -60 mV in the evening RMP = -50 in the middle of the night During each experiment, you apply the same amount of your transmitter Z and measure its effect on membrane potential, getting the following results in mV What type of clamp are you recording in

current clamp

what is the first thing to do when you see a graph

figure out the axis!

the neurobiological concept of localization of function means

that different regions of the brain are involved in different functions

Ion 2 (B+) has a higher concentration inside the neuron compared to the extracellular fluid. to determine which ion contributes to the resting membrane potential, you experimentally increase the concentration gradient of B+ by doubling its concentration in the extracellular fluid. To complete this experiment, what should you measure

membrane potential

you are recording a neuron in whole-cell patch clamp in current clamp configuration. at the time indicated with the above graph, you activate synapses that open chloride (Cl-) channels. How will the membrane potential react to the activation of these synapses

the membrane potential will hyperpolerize

the rate limiting step for serotonin synthesis is the availability of

tryptophan