What effect would the neurotoxin have on function of neurons

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Assignment

1) Which of the following is not true regarding the establishment of a neuron's resting potential?

A) Chemical and electrical forces both favor sodium ions entering the cell.

B) Electrical forces push sodium ions into the cell.

C) The chemical gradient for potassium ions tends to drive them out of the cell.

D) Ion pumps in the plasma membrane eject sodium ions as fast as they cross the membrane.

E) Resting membrane permeability to Na+ is very low.

2) At the normal resting potential of a typical neuron, its sodium-potassium exchange pump transports

A) 1 intracellular sodium ion for 2 extracellular potassium ions.

B) 2 intracellular sodium ions for 1 extracellular potassium ion.

C) 3 intracellular sodium ions for 1 extracellular potassium ion.

D) 3 intracellular sodium ions for 2 extracellular potassium ions.

E) 3 extracellular sodium ions for 2 intracellular potassium ions.

3) Ion channels that are always open are called ________ channels.

A) active

B) gated

C) leak

D) regulated

E) local

4) Opening of sodium channels in the axon membrane causes

A) depolarization.

B) repolarization.

C) hyperpolarization.

D) increased negative charge inside the membrane.

E) inhibition.

5) Voltage-gated channels are present

A) at the motor end plate.

B) on the surface of dendrites.

C) in the membrane that covers axons.

D) on the soma of neurons.

E) along the perikaryon of neurons.

6) The sodium-potassium ion exchange pump

A) must reestablish ion concentrations after each action potential.

B) transports sodium ions into the cell during depolarization.

C) transports potassium ions out of the cell during repolarization.

D) moves sodium and potassium opposite to the direction of their electrochemical gradients.

E) depends on a hydrogen gradient for energy.

7) Integral membrane proteins that connect electrical synapses are called

A) connexons.

B) receptors.

C) desmosomes.

D) sodium channels.

E) synapsins.

8) ________ channels open or close in response to physical distortion of the membrane surface.

A) Voltage-gated

B) Chemically gated

C) Active

D) Mechanically gated

E) Leak

9) If the permeability of a resting axon to sodium ion increases,

A) the membrane potential will repolarize.

B) the membrane potential will hyperpolarize.

C) inward movement of sodium ion will increase.

D) outward movement of sodium ion will decrease.

E) inward movement of sodium will increase and the membrane will depolarize.

10) Graded potentials

A) produce an effect that increases with distance from the point of stimulation.

B) produce an effect that spreads actively across the membrane surface.

C) may be either a depolarization or a hyperpolarization.

D) are often all-or-none.

E) cause repolarization.

11) The all-or-none principle states that

A) all stimuli will produce identical action potentials.

B) all stimuli great enough to bring the membrane to threshold will produce identical action potentials.

C) the greater the magnitude of the stimuli, the greater the magnitude of the action potential.

D) only sensory stimuli can activate action potentials.

E) only motor stimuli can activate action potentials.

12) The same ________ can have different effects depending on the properties of the ________.

A) neurotransmitter; receptor

B) receptor; neurotransmitter

C) substrate; receptor

D) hormone; neurotransmitter

E) propagation; neurotransmitter

13) Which of the following statements about the action potential is false?

A) The rapid depolarization phase is caused by the entry of potassium ions.

B) During the repolarization phase, sodium channels close and potassium channels open.

C) During the depolarization phase, membrane potential becomes positive.

D) During the hyperpolarization phase, the ion pumps re-establish the sodium and potassium concentrations across the cell membrane.

E) Repolarization occurs as potassium ions leave the axon.

14) How would the absolute refractory period be affected if voltage-regulated sodium channels failed to inactivate?

A) It would last indefinitely.

B) It would be much briefer.

C) It would be basically unaffected.

15) During repolarization of a neuron

A) sodium ions move out of the cell.

B) potassium ions move out of the cell.

C) potassium ions move into the cell.

D) both sodium and potassium ions move into the cell.

E) sodium ions move into the cell.

16) How would a chemical that prevents the opening of voltage-regulated Na+ channels affect the function of a neuron?

A) The neuron will only be able to hyperpolarize.

B) The neuron will depolarize more rapidly.

C) Action potentials will lack a repolarization phase.

D) The neuron will automatically and repeatedly produce graded potentials.

E) The neuron will only be capable of producing graded potentials.

17) A threshold stimulus is the

A) depolarization necessary to cause an action potential.

B) peak of an action potential.

C) hyperpolarization of an axon.

D) resting potential.

E) electrical current that crosses the synaptic cleft.

18) Which of the following is true about threshold for an action potential?

A) It is more positive than the resting potential.

B) Voltage-gated potassium channels begin to close.

C) Voltage-gated potassium channels begin to open.

D) The membrane begins to hyperpolarize.

E) Threshold for a typical neuron is approximately -30 mV.

19) Puffer fish poison blocks voltage-gated sodium channels like a cork. What effect would this neurotoxin have on the function of neurons?

A) Neurons would depolarize more rapidly.

B) Action potentials would lack a repolarization phase.

C) The absolute refractory period would be shorter than normal.

D) The axon would be unable to generate action potentials.

E) None, because the chemically gated sodium channels would still function.

20) What is occurring at the area labeled #4?

A) An inhibitory stimulus has occurred.

B) Chemically gated potassium channels have opened.

C) Excessive potassium has diffused out causing hyperpolarization.

D) Sodium ions have been pumped out of the neuron.

E) Excessive depolarization of the axon has occurred.

21) What is occurring in the area between #2 and #3?

A) An excitatory graded potential is occurring.

B) Potassium ions are entering the axon and causing depolarization.

C) Chemically gated sodium channels are open and sodium is diffusing into the axon.

D) Sodium ions are entering the axon and causing depolarization.

E) Repolarization of the axon due to sodium ions leaving the axon is occurring.

22) Which area of the graph shows when chemically gated sodium channels are open?

A) 3

B) 1

C) 2

D) 5

E) 4

23) Which area of the graph shows when voltage-gated sodium channels are open?

A) 2

B) 4

C) 1

D) 5

E) 3

24) Which area of the graph shows when potassium channels open?

A) 1

B) 2

C) 3

D) 4

25) Which area of the graph occurs when there is a sudden rush of sodium ions into the neuron?

A) 1

B) 2

C) 3

D) 4

26) Which area of the graph shows when membrane potential approaches the potassium equilibrium potential?

A) 1

B) 2

C) 3

D) 4

27) Which point of the graph shows when potassium ion outflow exceeds sodium ion inflow?

A) 1

B) 2

C) 3

D) 4

28) When is the neuron in the refractory period?

A) 1

B) 2

C) 3

D) 4

29) A movement of charges in response to a potential difference is called

A) current.

B) depolarization.

C) hyperpolarization.

D) action potential.

E) electricity.

30) The separation of positive and negative charges across the membrane creates a ________ difference, or voltage.

A) thermodynamic

B) permeability

C) dialysis

D) electrochemical

E) potential

31) The sum of the electrical and chemical forces acting on an ion is known as its

A) permeability gradient.

B) thermodynamic difference.

C) electrochemical gradient.

D) action potential.

E) summation difference.

32) The period during which an excitable membrane can respond again, but only if the stimulus is greater than the threshold stimulus, is the ________ period.

A) relative refractory

B) absolute refractory

C) resting

D) lag

E) stationary

33) During embryonic development, which of the following secondary brain vesicles will form the cerebrum?

A) telencephalon

B) diencephalon

C) mesencephalon

D) metencephalon

E) myelencephalon

34) Which of these is not one of the main divisions of the adult brain?

A) cerebrum

B) diencephalon

C) prosencephalon

D) midbrain

E) pons

35) Which of the following lies between the cerebrum and the brain stem?

A) medulla oblongata

B) pons

C) mesencephalon

D) diencephalon

E) cerebellum

36) The floor of the diencephalon is formed by the

A) hypothalamus.

B) thalamus.

C) brain stem.

D) mesencephalon.

E) myelencephalon.

37) The tracts that connect the cerebellum to the brain stem are located in the

A) medulla oblongata.

B) pons.

C) mesencephalon.

D) diencephalon.

E) thalamus.

38) Autonomic centers that control blood pressure, heart rate, and digestion are located in the

A) medulla oblongata.

B) pons.

C) mesencephalon.

D) diencephalon.

E) cerebellum.

39) The cerebellum and pons develop from the

A) telencephalon.

B) diencephalon.

C) mesencephalon.

D) metencephalon.

E) myelencephalon.

40) Sensory information is processed and relayed to the cerebrum by the

A) medulla oblongata.

B) pons.

C) midbrain.

D) thalamus.

E) cerebellum.

41) A neural cortex is found on the surface of the

A) cerebrum.

B) pons.

C) thalamus.

D) midbrain.

42) The ventricle associated with the pons and upper medulla is the

A) first.

B) second.

C) third.

D) fourth.

E) lateral.

43) The control of heart rate and blood pressure is based in the

A) cerebrum.

B) cerebellum.

C) diencephalon.

D) medulla oblongata.

E) heart.

44) The medulla oblongata regulates

A) somatic motor contractions.

B) food intake.

C) auditory reflexes.

D) vision and hearing

E) blood pressure and respiration.

45) The respiratory rhythmicity center is located in the

A) pons.

B) cerebrum.

C) medulla oblongata.

D) cerebellum.

E) midbrain.

46) If the pons was damaged, which of the following functions would be affected?

A) breathing

B) control of blood pressure

C) coordination

D) sleep patterns

E) judgment

47) Overseeing the postural muscles of the body and making rapid adjustments to maintain

balance and equilibrium are functions of the

A) cerebrum.

B) mesencephalon.

C) cerebellum.

D) pons.

E) medulla oblongata.

48) The structure of the brain that carries ascending sensory information to the thalamus is the

A) midbrain.

B) cerebral aqueduct.

C) 4th ventricle.

D) basal ganglion.

E) cerebellum.

49) The pineal gland is part of the

A) hypothalamus.

B) diencephalon.

C) midbrain.

D) mesencephalon.

E) 3rd ventricle.

50) Which of the following is a function of the hypothalamus?

A) produces ADH

B) controls autonomic centers

C) regulates body temperature

D) secretes oxytocin

E) All of the answers are correct.

51) Any stimulus that opens a ________ ion channel will produce a graded potential.

A) voltage-gated

B) chemically gated

C) sodium

D) mechanically gated

E) All of the answers are correct.

52) Raising the potassium ion concentration in the extracellular fluid surrounding a nerve cell will have what effect?

A) depolarize it

B) hyperpolarize it

C) increase the magnitude of the potassium equilibrium potential

D) decrease the magnitude of the potassium equilibrium potential

E) both hyperpolarize it and decrease the magnitude of the potassium equilibrium potential

53) As you ascend from the medulla oblongata to the cerebrum, the functions of each successive level become

A) more complex.

B) simpler.

C) better understood.

D) more crucial to visceral functions.

E) critical to reflexes.

54) The most obvious feature that one notices about the cerebrum is the

A) smoothness of the surface of the cortex.

B) extensiveness of the gyri and sulci.

C) small size of it compared to other brain areas.

D) transverse fissure running through it.

E) color of the cerebrum compared to the other brain areas.

55) Jane, a 79-year-old woman, has been diagnosed with a tumor in the brain. She has lost some sensory and motor functions associated with the face, like control of facial muscles for emotion and various sensory functions like taste. In addition, she has some hearing loss and balance problems. The location of the tumor is likely to be the

A) cerebellum.

B) cerebrum.

C) medulla.

D) thalamus.

E) pons.

Reference no: EM131419336

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