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