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10 Dec 2018

Which conducts an action potential faster and why?

a. myelinated fibers, the action potential moves through the myelin which allows it to travel faster b. myelinated fibers, the action potential jumps from one node of Ranvier to another c. unmyelinated fibers, the absence of myelin allows the action potential to travel faster d. unmyelinated fibers, the action potential jumps from one node of Ranvier to another e. unmyelinated fibers, the ions can move in and out of the cell fasters without the myelin coating

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Deanna HettingerLv2

11 Dec 2018

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Related questions

59. Saltatory Conduction

a. occurs in unmyelinated nerve fiber

b. is slower than conduction by local current flow because the myelin acts as an insulator to show the impulse down

c. involves the impulse jumping from one node of ranvier ro adjacent node

d. refers to the action potential spreading from one schwann cell to the adjacent schwann cell.

e. more than one of the above is correct

63. the universal energy currency in cells is

a. RNA b. ATP c. Glucose d. Glucogen e. DNA

66. which of the classes of hormones triggers the synthesis of new intracellular proteins within the target cell (via stimulation of DNA transcription and translation)?

a. peptides b. catecholamines c. steroids d. thyroid hormone e. both c and d are correct

68. hormones,

a. are all similar chemical composition

b. combine with specific receptors on the target cell's surface or inside the target cell

c. are secreted at a constatnt rate

d. all act by activating adenyl cyclase, which transforms ATP into cAMP

e. all of the above are correct

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

Which of the following statements is FALSE? (choose one)

A.	Voltage-gated sodium (Na+) channels open in the dendrites and cell body during a local, graded potential.

B.	During repolarization, potassium ions are leaving the cell (K+ is diffusing out of the cell), and the inside of the cell becomes more negative

C.	If someone damaged an efferent motor neuron, they could feel pain, but not respond to move away from the pain

D.	Myelin serves as electrical insulation and increases the speed at which an action potential travels along the axon

E.	Movement of ions can be excitatory (if sodium ligand-gated channels bind the neurotransmitter), or inhibitory (if potassium ligand-gated channels bind the neurotransmitter)