Chapter 11: nerves

What specific part of the neuron communicates with a target cell and serves as the secretory region of the cell?

Axon terminals (synaptic knobs)

What best describes a converging circuit?

Axon terminals from multiple input neurons join onto a single postsynaptic neuron

Which of the following are organs of the central nervous system?

Brain and spinal cord

What ion triggers synaptic vesicles to release neurotransmitters into the synaptic cleft?

Calcium

Determine the direction in which an electrical signal is carried in a typical multipolar neuron.

Dendrites, cell body, axon

Which of the following is most likely to produce an action potential?

Excitatory postsynaptic potential (EPSP)

The concentration of K+ is higher inside than outside the cell.

K+

The membrane is more permeable to K+.

K+

During an action potential, hyperpolarization is caused by:

K+ efflux

The resting membrane potential is maintained by Na+-K+ pumps that actively transport ___ into and ___out of the cell.

K+, Na+

What type of ion channel is always open?

Leak

Which type of fiber has the largest diameter?

Type A

Where are neuronal pools located?

Within the CNS

A bundle of axons in the PNS is called __________.

a nerve

Cholinergic synapses use the neurotransmitter __________.

acetylcholine

Involuntary control of smooth and cardiac muscles and glands is provided by the __________.

autonomic nervous system

The conducting region of the neuron is the __________.

axon

What ion triggers synaptic vesicles to release neurotransmitters into the synaptic cleft?

calcium

The brain and spinal cord compose the __________.

central nervous system

Bundles of axons known as tracts are part of the __________.

central nervous system (CNS)

The two anatomical divisions of the nervous system are the:

central nervous system and peripheral nervous system.

Bundles of axons known as tracts are part of the:

central nervous system.

The majority of synapses in the nervous system are __________.

chemical

What type of synapse must have receptors to transmit signals?

chemical synapse

Ependymal cells:

circulate cerebrospinal fluid.

Action potential propagation in unmyelinated axons happens via:

continuous conduction

Which of the following is one of the mechanisms for termination of synaptic transmission?

degradation of neurotransmitter by enzyme

Multiple sclerosis is an autoimmune disease that destroys myelin in the CNS. Which of the following would be a symptom of multiple sclerosis?

delay in neural conduction

The short, branched cytoplasmic extensions that allow neurons to receive input signals are called __________.

dendrites

The influx of positive charges makes the membrane potential more positive and is known as __________.

depolarization

Depolarization to threshold during action potential propagation in axons is due to:

diffusion of Na ions down to the next segment of the axon

What is NOT a function of the nervous system?

direct long-term functions such as growth

Which of the following is NOT a function of neurons?

forming the myelin sheath

Loss of K ions from the cytosol will have the same effect as:

gain of Cl ions

The relative refractory period is caused by:

hyperpolarization

A series of measurements with a voltmeter show a neuron's membrane potential becoming more negative, from -70 mV to -85 mV. This neuron is experiencing a __________.

hyperpolarization phase

A series of measurements with a voltmeter show a neuron's membrane potential becoming more negative, from -70 mV to -85 mV. This neuron is experiencing a:

hyperpolarization phase.

Batrachotoxin produced by certain species of frogs is a toxin that permanently opens voltage-gated Na ion channels. The results of exposure to batrachotoxin will be:

inability to generate action potentials

Conduction speed will be fastest in a __________.

large myelinated axon

The most common type of neuron in the human body is __________.

multipolar

The most common type of neuron in the human body is:

multipolar

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

neurotransmitter; receptor

The same __________ can have different effects depending on the properties of the __________.

neurotransmitter; receptor

If a neuron simultaneously receives a stimulus that results in local depolarization of 10 mV and a stimulus that results in a local hyperpolarization of 10 mV, the net effect would be:

no net change in membrane potential

During saltatory conduction, action potentials are generated __________.

only at nodes of Ranvier of myelinated axons

The autonomic nervous system does not carry signals to __________.

skeletal muscle

Sarah sensed a mosquito land on her arm and swatted it away with her hand. Which specific PNS division was responsible for the movement of Sarah's hand?

somatic motor division

Upon entering your house, you noticed the smell of cake baking in the oven. What division of the peripheral nervous system is responsible?

somatic sensory division

Simultaneous stimulation from multiple presynaptic neurons will result in __________.

spatial summation

A neurotransmitter may have an excitatory or an inhibitory effect on the postsynaptic cell, depending on __________.

the receptor to which it binds

Resting membrane potential is maintained by the Na+/K+ pump, which brings __________.

two potassium ions into the cytosol and three sodium ions into the extracellular fluid

The channels that open when the axolemma reaches threshold depolarization are the:

voltage-gated Na ion channels

Place these steps of the action potential in the correct order. 1. Sodium ions channels return to the resting state and repolarization continues. 2. Voltage-gated sodium ion channels activate, sodium ions enter, and the axon section depolarizes. 3. As potassium ion channels return to resting state, the axolemma may hyperpolarize before returning to the resting membrane potential. 4. A local potential depolarizes the axolemma of the trigger zone to threshold. 5. Sodium ion channels inactivate, and voltage-gated potassium ion channels activate, so sodium ions stop entering and potassium ions leave, beginning repolarization.

4, 2, 5, 1, 3

Which neuroglial cell helps form the blood-brain barrier?

Astrocyte

Because of their ability to rapidly divide during brain injury, which type of neuroglial cell would be more likely to form a brain tumor?

Astrocyte

Depolarizing local potentials are caused by an influx of:

Na ions via gated ion channels

The concentration of _____ is higher outside than inside the cell.

Na+

The Na+/K+ pump moves __________.

Na+ out of and K+ into the cell

Which of the following is controlled by the somatic motor division?

Skeletal muscle

Which neuropeptide neurotransmitter is released from fibers transmitting sensory information about pain and temperature?

Substance P

When a second EPSP arrives at a single synapse before the effects of the first have disappeared, what results?

Temporal summation

Regeneration of neural tissue in the PNS is possible only if the neuron's cell body remains intact.

True