HMB200H1 Study Guide - Midterm Guide: Benzodiazepine, Mechanosensitive Channels, Dopamine Receptor

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Describe all the parts of a neuron. What is the function of each part?

Dendrite: receive signal

Cell body: contains nucleus

Axon: pass down the signal

Axon terminal: pass down the signal to the next neuron

Describe the basis of the resting membrane potential. Your answer

should include the cell membrane as well as any important ions,

proteins, channels and pumps. Be able to describe ionic concentrations

inside and outside the neuron.

at RMP, the leak K+ ion channel and the Na+/K+ pumps are

active. Inside of the cell, there are mainly, K+ and proteins and

outside of the cell are mainly Na+ and Cl-. The ionic conc

difference is -60mV

Describe the basis of the action potential. Pay special attention to the

role of different types of channels in the various phases of the ion

potential.

AP is only generated when Na+ channel is open.

What is meant by the term 'net driving force’? How do we approximate

the net driving force of an ion?

Net driving force is the balance between chemical driving force

and electrical driving force. The driving force will cause the ions

to move across membrane.

At the resting membrane potential, what are the driving forces for

Na+, K+, Ca2+and Cl-?

Na+: moving inward

K+: outward

Cl-: not net movement

Ca2+: inward

What do we mean when we say the Na+/K+ exchanger is ‘energy-

dependent’?What do we mean when we say the exchanger is

electrogenic? What is the purpose of the exchanger?

It's energy-dependent because it requires ATP. It's electrogenic

because it can produce a change in the electrical potential of a

cell. The purpose of the exchanger to the maintain the difference

ionic conc between the inside and the outside of the cell.

Differentiate ligand-gated, voltage-gated and mechanosensitive

channels.

Ligand-gated: ions bind then activate a.

Voltage-gated: electrical current arrive, reach threshold then

activate

Mechanosensitive: when pressure, activatesc.

What is the Nernst equation? What is it for?

The Nernst equation is use for estimating the direction of a

specific ion flow at a given membrane potential.(estimate the

equilibrium potential for a given ions)

What is the Goldman-Hodgkin-Katz (GHK) equation? What is it for?

GHK equation is to estimate the membrane potential. It considers

more than one ion's permeability.

10.Why is myelin important for the nervous system? What cells are

responsible for

myelination?

Myelin is important for the NS because it speeds up the conduction

rate. Schwann cell is responsible for myelination in PNS.

Oligodendrocytes is responsible for myelination in CNS.

11.Describe the steps involved in converting an electrical signal (the action

potential) into a chemical signal (neurotransmitter release).

Action potential causes the opening of voltage gated Ca2+ channel 1.

Ca2+ bind with some proteins to form a complex, and these complexes

binds to vesicles

The binding cause the vesicles to release the neurotransmitter to the

extracellular site (exocytosis)

12.Describe the process by which a cell is driven to fire an action potential

and the

process by which a cell is inhibited from firing an action potential.

EPSP: by depolarizing the cell, and causes an inflow of cation.

IPSP: by hyperpolarizing the cell, and causes an inflow of anion

13.Differentiate ionotropic and metabotropic receptors.

Ionotropic: react quickly, ligand-gated receptors

Metabotropic: slow but persist, G-protein coupled protein receptors

14.Differentiate excitatory and inhibitory receptors. What types of receptors

are

inhibitory? What types are typically excitatory? What type of ionic

conductance is

associated with each receptor?

Excitatory receptors increase the probability of the cell firing -

glutamate receptors (depolarization due to influx of Na+)

Inhibitory receptors decrease the probability of a cell firing - GABA and

glycine receptors (hyperpolarization due to efflux of K+ and influx of

Cl-)

15.Explain the concepts of temporal and spatial summation.

Temporal summation: only a few active synapses, but each generating

EPSPs at high frequency

Spatial summation: each dendrite generated at a different synapse

16.Explain length and time constants.

Length constant: an estimate of distance that a EPSP will travel before

declining to 37% of its original value. (relevant to spatial summation)

Time constant: an estimate of time that a EPSP will travel before

declining to 37% of its original value (relevant to temporal summation)

17.What types of synapses exist in the nervous system?

Axondendric, axoaxonic, axosecretory, dendrodendritic,

axoextracelluar, axosomatic, axosynaptic

18.What are likely molecular (receptor) targets of alcohol, barbiturates and

benzodiazepines?

GABA receptors

19.What effects do amphetamine, cocaine and chlorpromazine have on the

nervous

system?

Amphetamine and cocaine block the transport of Dopamine.

Amphetamine also promote release of Dopamine.

Chlorpromazine blocks the subtype of dopamine receptor, preventing

its action.

20.Describe rate encoding and population encoding. How does information

encoding

work in most cases?

Rate encoding is encoding of info by firing rate

Population encoding: certain neurons are responsible for specific

functions

Information encoding works with both rate and population encoding

Distributed encoding: a small population of few neurons can

represent many stimuli thru firing rates

○

21. Describe the effects of tetraethylammonium (TEA) and tetrodotoxin

(TTX) on channels in the cell. How will each compound affect the action

potential?

TEA blocks the voltage-gated K+ channel

Length the action potential

○

TTX blocks the voltage-gated Na+ channel

No action potential will be generated

○

22.What is Temple-Baraitser syndrome? Describe how this syndrome has

implications

for the nervous system.

Temple-Baraitser syndrome: mutation in a type of K+ channel. Channels

produced from the mutant gene have decreased threshold of activation and

delayed deactivation

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Document Summary

What is the function of each part? a. b. c. d. Axon terminal: pass down the signal to the next neuron. Describe the basis of the resting membrane potential. Your answer should include the cell membrane as well as any important ions, proteins, channels and pumps. Be able to describe ionic concentrations inside and outside the neuron. a. at rmp, the leak k+ ion channel and the na+/k+ pumps are active. Inside of the cell, there are mainly, k+ and proteins and outside of the cell are mainly na+ and cl-. Pay special attention to the role of different types of channels in the various phases of the ion potential. a. Ap is only generated when na+ channel is open. How do we approximate the net driving force of an ion? a. Net driving force is the balance between chemical driving force and electrical driving force. The driving force will cause the ions to move across membrane.

Related Questions

Why do ion channels not function like open pores?

What is membrane potential?

How do K⁺ leak channels work? Why is the membrane potential of a resting cell negative?

What is patch clamp recording? What is one of the major insights gained from patch clamp reporting experiments?

Compare and contrast the three types of gated ion channels.

Be familiar with the different parts of a neuron.

During an action potential, what happens to the membrane potential, voltage-gated Na⁺ channels, Na⁺ ions, voltage gated K⁺ channels, K⁺ ions, and Na⁺-K⁺ ion pumps?

When an action potential reaches a synapse, what happens to the Ca²⁺ channels, Ca²⁺ ions, neurotransmitters, transmitter-gated ion channels, and the post synaptic neuron?

What effect do excitatory or inhibitory neurotransmitters have on postsynaptic cells?

What is an example of a mechanically gated ion channel?

Santiago Ramon y Cajalâs theory of dynamic polarization refers to the:

(a)membrane potential of a neuron at rest.

(b)membrane potential of a neuron firing action potentials.

(c)opening and closing of gated channels in the membrane.

(d)one way flow of information in neurons from dendrites to axon terminals.

(e)one way flow of information in neurons from axon terminals to dendrites.

Over the course of scientific history, there are many examples of scientists reaching the right conclusion for the wrong reasons. When Schwann first proposed that the nervous system was made of individual cells, he based it on observations of:

(a)synapses.

(b)dendrites

(c)axon terminals.

(d)astrocytes.

(e)Nodes of Ranvier.

The synaptic cleft was finally seen in the 1950s. What prevented scientists from seeing it earlier?

(a)The resolution of the light microscope.

(b)They were looking in the wrong place.

(c)Their tissue was not appropriately stained.

(d)Myelination of the axons.

(e)all of the above

The resting membrane potential of a neuron is approximately:

(a) +65 V

(b) +65 mV

(d) -65 mV

What is largely responsible for the resting membrane potential in a neuron?

(a)Axonal insulation by myelin

(b)Voltage-Gated Sodium Channels

(c)The Action Potential

(d)Potassium Leak Channels

Which of the following would DECREASE the propagation velocity of an action potential down an axon?

(a)Increase in axon diameter

(b)Increase myelination between nodes of Ranvier

(c)Remove myelination between nodes of Ranvier

(d)Decrease density of voltage-gated Na+ channels except at the Nodes of Ranvier

The resting membrane potential of a neuron can be estimated using the:

(a)Nernst equation

(b)Goldman equation

(c)Hodgkin and Huxley equation

(d)Ohmâs law

18. What would happen to the resting membrane potential of a neuron if you added K+ to the extracellular fluid?

(a)Resting membrane potential would increase (become more positive)

(b)Resting membrane potential would decrease (become more negative)

(c)Resting membrane potential would not change

(d)Resting membrane potential would be abolished

. Which of the following statements is FALSE for Graded Potentials

(a)Magnitude changes with magnitude of triggering stimulus

(b)Magnitude decreases with distance from initial site

(c)Cannot be summed

(d)No refractory period

In the nervous system, the strength of the stimulus is coded into:

(a)The frequency of action potentials generated

(b)The amplitude of action potentials generated

(c)Both the frequency and amplitude of action potentials generated

(d)The duration of individual action potentials generated

Ion movement during both the depolarization and repolarization phases of an action potential are the result of:

(a)active transport pumps along the neuron membrane.

(b)diffusion of ions down their electrochemical concentration gradients.

(c)negative feedback loops.

(d)All of the above

At the peak of the action potential, the membrane potential is:

(a)Exactly at the Na+ equilibrium potential

(b)Greater (more positive) than the Na+ equilibrium potential

(c)Above 0 mV but less positive than the Na+ equilibrium potential

(d)0 mV

1. The plasma membrane of liver cells contains a glucose uniportthat transports glucose by facilitated diffusion. When the[glucose] is higher inside the liver cell than the [glucose]outside the liver cell, the glucose uniport will

A. couple the transport of glucose out of the cell to thehydrolysis of ATP

B. couple the transport of glucose into the cell to thehydrolysis of ATP

C. switch to a closed conformation, allowing no transport ofglucose

D. transport glucose out of the cell by passive transport

E. transport glucose in of the cell by passive transport

2. Unlike the positive charged ion shown in the middle diagramof figure 11-4B, K+ is higher in concentration inside the cell. Howwill the membrane potential of a cell at rest (shown in both themiddle and right-hand diagrams of Figure 11-4B) affect theelectrochemical gradient for K+?

A. The membrane potential will increase the electrochemicalgradient

B. The membrane potential will decrease the electrochemicalgradient

C. The membrane potential will have no effect on theelectrochemical gradient

3. Which of the following proteins carries out activetransport?

A. gluclose symport

B. Bacteriorhodopsin

C. ABC transporter

D. NA K pump

E. All of the above

4. Aquaporin will not transport Na+ ions because

A. Two asparagine residues in the channel prevent the passage ofNa+ ions by binding the oxygen of each water molecule as it passesby

B. Na+ ions are repelled by the positive charges at the entranceto the channel

C. Na+ ions cannot make contact with the carbonyl (C=O) groupson all four sides of the channel

D. The passage of Na+ ions is energetically unfavorable becauseone side of the channel is hydrophobic in nature

5. The acetylcholine receptor is different from other channelproteins we have discussed, such as the K+ leak channel,because

A. The acetylcholine channel is composed of a single polypeptiderather than multiple subunits

B. The acetylcholine channel transports Na+ ions against theconcentration gradient for sodium

C. The acetylcholine channel has a much smaller diameter thanother channel proteins

D. The acetylcholine channel transports ions with theirassociated shell of water molecules

E. The acetylcholine channel is always open, and never switchesto a closed conformation

6. After opening briefly along the axon of a neuron,voltage-gated ion channels switch to an inactivated conformationthat slowly returns to the original closed conformation of theprotein. This slow change in conformation, requiring about amillisecond, is important because

A. all of the ions that were transported across the membranewhen the ion channels were open must be actively transported backto the other side of the membrane, restoring the originalconcentration gradient, before the ion channels can open again

B. ATP hydrolysis is necessary to drive this energeticallyunfavorable change in conformation

C. it prevents the action potential from reversing direction andtraveling back toward the cell body of the neuron

D. the channel protein must be dephosphorylated in order tocomplete the transport process and return to the originalnonphosphorylated conformation

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HMB200H1 Study Guide - Midterm Guide: Benzodiazepine, Mechanosensitive Channels, Dopamine Receptor

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