Smartbook 5

The resting potential of many vertebrate neurons ranges from ____________ mV to _______________ mV.

-40,-90

The resting potential of many vertebrate neurons ranges from _____________ mV to ________________ mV.

-40,-90

How many axons does each neuron have?

1

Place the changes that occur in a voltage-gated sodium channel as the membrane potential reaches the threshold value, starting at the top.

1. Activation gate opens 2. Inactivation gate closes 3. Activation gate closes and inactivation gate opens

Arrange the following statements placing the first one on top according to how a neuron relays information, starting at the top.

1. Information reaches dendrites 2. Excitation of membrane rises 3. Nerve impulses are triggered 4. Impulses are conducted along axon.

The sodium-potassium allows _____________ K ions to enter into the cell for every _______________ Na ions that are taken out of the cell.

2 or two, 3 or three

The sodium-potassium allows ________________K ions to enter into the cell for every ____________________Na ions that are taken out of the cell.

2 or two, 3 or three

The sodium-potassium allows _______________ K ions to enter into the cell for every _____________ Na ions that are taken out of the cell.

2,3

The functional behavior of gated ion channels can be likened to which of the following?

A door that can open or close

Which of the following are most important to the resting potential of a neuron?

Actions of the sodium-potassium pump The differential permeability of the membrane to Na+ and K+

Sensory neurons are also referred to as which of the following?

Afferent neurons

Which of the following explains why action potentials do not add together?

After firing, Na+ channels are in an inactivated state.

Which of the following occurs when the threshold voltage is reached?

An influx of Na+ ions Rapid opening of the activation gate of sodium channels

Why does an action potential signal propagate along the length of an axon (without backing up)?

Because the Na+ channels that have just fired are still refractory to stimulation

Why is the sodium-potassium pump important?

Because the pump establishes a concentration gradient Because the pump causes an imbalance in cations outside the cell Because they contribute to the long-term maintenance of resting potential

Why is the sodium-potassium pump important?

Because the pump establishes a concentration gradient Because they contribute to the long-term maintenance of resting potential Because the pump causes an imbalance in cations outside the cell

Which of the following is a neural adaptation to increase the surface area of a neuron available to receive stimuli?

Dendritic spines

_____________________ potentials are small, continuous changes to the membrane potential, while _______________ potentials are sharp, transient alterations to the membrane potentials.

Graded, action

_____________________ (association neurons) are located in the brain and the spinal cord of vertebrates, where they help provide complex reflexes and higher associative functions.

Interneurons

During the falling phase of an action potential, the opening of the K+ channels causes which of the following to occur?

K+ to diffuse out of the cell

All of the following are true for a voltage gated Na+ channel returning to its resting state except which one?

Opening of activation gate

The autonomic nervous system is subdivided into which of the following divisions?

Parasympathetic Sympathetic

An action potential is propagated along the axon pathway by which of the following?

Recreating the action potential in adjacent stretches of axon membrane

The major effect that occurs when the activation gate of the K+ channel opens is which of the following?

Repolarization of the membrane

Identify the action potential phase associated with the following characteristics: Na+ channels open rapidly; influx of Na+ ions into cell.

Rising phase

Which type of muscle tissue is controlled by motor neurons of the somatic nervous system?

Skeletal

The autonomic nervous system is subdivided into which of the following divisions?

Sympathetic Parasympathetic

Which of the following are part of the falling phase of an action potential?

The K+ channel opens K+ diffuses out of the cell The membrane becomes repolarized

The membrane of a neuron is able to repolarize after voltage-gated K+channels open for which of the following reasons?

The high concentrations of K+ inside the cell causes an efflux. The efflux of K+ is able to counteract the effects of the Na+ channel.

What prevents the membrane potential from reaching +60mV during the rising phase of an action potential?

The inactivation gate of the Na+ closes.

Which of the following are part of the falling phase of an action potential?

The membrane becomes repolarized K+ diffuses out of the cell The K+ channel opens

Which of the following are part of the rising phase of an action potential?

The membrane potential shifts towards the equilibrium potential for Na+ The Na+ channel rapidly opens

Action potentials are separate, all-or-none events that result from which of the following?

The passive diffusion of ions

Which of the following helps to establish ion concentration gradients and maintain resting membrane potential?

The sodium-potassium pump

Which of the following describes the function of the sodium-potassium pump?

The sodium-potassium pump establishes concentration gradients for Na+ and K+ by transporting Na+ out and K+ into the cell.

Which of the following describes the events of action potentials?

They are all or none events. They are separate events.

Which of the following describes the events of action potentials?

They are separate events. They are all or none events.

When a particular level of depolarization is reached, a nerve impulse, or _______________ potential is produced.

action

The nature of __________________ potentials is such that they do not add together or interfere with one another, as __________________ potentials do.

action, graded

An _______________ ________________ that originates at an axon base is recreated along the membrane of an axon pathway until the end of the axon is reached.

action, potential

An _______________ ___________________ that originates at an axon base is recreated along the membrane of an axon pathway until the end of the axon is reached.

action, potential

The rising phase, falling phase, and undershoot phase are the three phases of a(n) __________________ ___________________ .

action, potential

The rising phase, falling phase, and undershoot phase are the three phases of a(n) ___________________ _________________ .

action, potential

The nature of __________________ potentials is such that they do not add together or interfere with one another, as _______________ potentials do.

action,graded

An action potential is triggered at the base of a(n) ________________ when the membrane potential reaches a certain threshold level.

axon

An action potential is triggered at the base of a(n) _________________________ when the membrane potential reaches a certain threshold level.

axon

Motor and associative neurons must be able to receive many different information inputs simultaneously. To deal with this, their dendrites are highly _________________ relative to other types of neurons.

branched

The brain the spinal cord comprise the __________________ nervous system of vertebrates.

central

The brain the spinal cord comprise the ____________________ nervous system of vertebrates.

central

Cytoplasmic extensions of the cell body of neurons are called __________________ .

dendrites

Motor and associative neurons are able to receive information from many different sources simultaneously because of their profusion of highly branched ________________ .

dendrites

Motor and associative neurons are able to receive information from many different sources simultaneously because of their profusion of highly branched ___________________ .

dendrites

A neuron integrates information arriving at its ________________ via the membrane of the cell body. If the resulting excitation is sufficient, it triggers the conduction of impulses away from the cell body along the ________________ .

dendrites or dendrite, axon or axons

A neuron integrates information arriving at its ________________ via the membrane of the cell body. If the resulting excitation is sufficient, it triggers the conduction of impulses away from the cell body along the _________________ .

dendrites or dendrite, axon or axons

Once it is generated at the base of an axon, an action potential propagates along the axon because the positive charges due to the influx of sodium ions _____________________ the adjacent region of membrane to the _________________ potential.

depolarizes, threshold

Once it is generated at the base of an axon, an action potential propagates along the axon because the positive charges due to the influx of sodium ions _____________________ the adjacent region of membrane to the ____________________ potential.

depolarizes, threshold

Myelinated axons conduct nerve impulses ____.

faster than unmyelinated axons

A small, continuous change to the membrane potential of a neuron is called a(n) ________________ potential.

graded

Ligand-gated channels are important for producing ______________ potentials, while voltage-gated channels are involved in the production of _______________ potentials.

graded, action

__________________ potentials are small, continuous changes to the membrane potential, while _________________ potentials are sharp, transient alterations to the membrane potentials.

graded, action

Neurons of the somatic nervous system that control skeletal muscles are called _______________ neurons.

motor or efferent

A potential difference exists across every cell's plasma membrane. The side of the membrane exposed to the cytoplasm is the __________________ charged pole, while the side exposed to the extracellular fluid is the _________________ charged pole.

negatively or negative, positively or positive

The opening of the activation gate of the K+ channel causes a ___________________ of the cell membrane as a result of an __________________ of K+ ions.

repolarization or repolarizing, efflux, exit, or departure

The opening of the activation gate of the K+ channel causes a _______________ of the cell membrane as a result of an _________________ of K+ ions.

repolarization or repolarizing; efflux, exit, or departure

The _________________ membrane potential of a neuron arises due to the action of the sodium-potassium pump and the differential permeability of the membrane to Na+ and K+ due to ion channels.

resting

The action potential has three phases: a _____________ phase, a ________________ phase, and an ______________ phase.

rising, falling, undershoot

In myelinated axons, the nerve impulse appears to jump from one node of Ranvier to the next. This type of nerve impulse conduction is called _________________ conduction.

saltatory

Motor neurons of the somatic nervous system stimulate ____________________ muscles to contract, while motor neurons of the autonomic nervous system regulate the activity of ____________________ muscles, cardiac muscle, and __________________.

skeletal, smooth, glands or gland cells

The action potential generated by a membrane channel do not back up because after firing, the _______________ channels remain in an inactivated state and are refractory to stimulation.

sodium, Na, or Na+

The action potential generated by a membrane channel do not back up because after firing, the __________________ channels remain in an inactivated state and are refractory to stimulation.

sodium, Na, or Na+

Some neurons have dendritic _________________ that increase the neuron's surface area available to receive stimuli.

spines

Some neurons have dendritic ___________________ that increase the neuron's surface area available to receive stimuli.

spines

In vertebrates, there are two subdivisions of the autonomic nervous system, the _____________ division, and the _____________ division.

sympathetic, parasympathetic

The two main divisions of the vertebrate nervous system are ____.

the central and the peripheral nervous systems