Anatomy Ch12

The structural classification of neurons is based on the number of processes that extend from the neuron cell body. Match these definitions to the correct term

1. Many dendrites and a single axon Multipolar neuron 2. One dendrite and one axon Bipolar neuron 3. One process with two branches; one extending to the CNS, one extending to the periphery Unipolar neuron

What is the correct order for the events of neurotransmitter release from the synaptic terminal?1. Extracellular Ca2+ enters terminal and binds to sensor protein in the cytoplasm2. Exocytosis of neurotransmitter into synaptic cleft3. Action potential reaches axon terminal4. Ca2+-protein complex stimulates fusion of the docked synaptic vesicle with the plasma membrane5. Voltage-gated Ca2+ channels open

3, 5, 1, 4, 2

Which glial cell is starlike in shape and helps form the blood-brain barrier?

Astrocytes

While waiting for your food at your favorite restaurant, you see your favorite dish being carried to the table next to yours. The sight and smell of the food causes your salivary glands to produce saliva. What type of neuronal circuit caused this single reaction from the multiple stimuli you experienced?

Converging circuit

What type of cells produce the myelin sheath in the central nervous system (CNS)?

Oligodendrocytes

When sodium enters the neuron via chemically gated sodium channels, the membrane will depolarize. Therefore, the membrane potential will become more

Positive

Which part of a neuron contains calcium pumps and channels?

Synaptic bulbs

Which of the following characteristics of action potentials can vary?

The frequency of action potentials

Scorpion agitoxin is a neurotoxin that blocks the activity of voltage-gated potassium channels. In the presence of agitoxin, which will occur during an action potential?

The neuron will remain depolarized and unable to repolarize.

During the transmission of an action potential along a myelinated axon, as one neurofibril node is depolarizing, the previous node is repolarizing.

True

If extracellular calcium was absent, which would likely be true?

Vesicles containing neurotransmitter would not merge with the plasma membrane.

A recently depolarized area of a cell membrane cannot generate an action potential because of the

absolute refractory period

The _______ is a period when a membrane cannot respond to another stimulus (no matter how strong).

absolute refractory period

To enhance the effect acetylcholine has in a particular synapse, a drug may block acetylcholinesterase (AChE) so that

acetylcholine is not destroyed and will remain in the synapse longer.

Pain receptors in the skin send signals to the CNS for processing. These pain receptors are an example of ____________ neurons.

afferent

The fundamental physiological properties that enable nerve cells to communicate with other cells are

all of these choices are correct

When threshold is reached, depolarization occurs with the same amplitude of potential change. This is known as

all or none principle

Acetylcholinesterase

catalyzes hydrolysis of ACh to remove it from the synaptic cleft.

Nitric oxide is a neuromodulator that

causes some blood vessels to dilate.

Ependymal cells help produce

cerebrospinal fluid.

When a neurotransmitter binds a protein channel, it opens and lets sodium diffuse down its concentration gradient. This is an example of a

chemically gated sodium channel.

Classifying axons into types A, B, and C is based on their

conduction velocity.

Upon binding of endocannabinoids to their target, there is a(n)

decrease neurotransmitter release from presynaptic neurons.

An EPSP will cause the postsynaptic membrane

depolarize

A small group of neurons in the brain coordinating the action of many leg, back, and arm muscles during running is an example of a

diverging circuit.

Neurons that carry signals from the CNS to skeletal muscle for contraction would be classified as _____________ neurons.

efferent

On a graph of an action potential, the small depolarizations that lead to threshold are from

excitatory postsynaptic potentials (EPSPs).

A neuromodulator is another name for a neurotransmitter.

false

EPSPs and IPSPs have a long-term effect on a neuron.

false

Ganglia are clusters of neuron cell bodies located within the CNS.

false

Glial cells help neurons by generating action potentials.

false

Greater current flow is possible with larger resistance and a lower voltage.

false

Individual EPSPs and IPSPs determine whether or not a neuron fires and the rate of firing by stimulating or inhibiting the production of more action potentials.

false

Nerve impulses relaying pain would most likely use saltatory conduction.

false

Neurons are unique in that they do not require glucose or oxygen to function.

false

One function of the nervous system is to always respond to sensory input.

false

The endoneurium wraps around groups of fasicles to form a nerve.

false

An axon with a large diameter transmits an impulse ____ than an axon with a smaller diameter.

faster

If neurotransmitter from Neuron A causes Neuron B to hyperpolarize, this is an example of an

inhibitory postsynaptic potential.

An excitatory postsynaptic potential (EPSP)

may result from positively charged ions entering the postsynaptic neuron.

The vagus nerve contains afferent and efferent neurons; therefore it is an example of a(n) __________ nerve.

mixed

The most common type of neuron contains many dendrites and a single axon. Structurally, this is classified as a(n) ______________ neuron.

multipolar

Nerve growth factors that stimulate outgrowth of severed axons are secreted by

neurolemmocytes.

Neurolemmocytes produce myelin in the _____ nervous system.

peripheral

Myelin sheaths mainly consist of which part of the glial cells that form them?

plasma membrane

What type of neural circuit results in a repeating, cyclical response?

reverberating

The ___________ nervous system transmits information from receptors to the CNS, while the ___________ nervous system transmits information from the CNS to the rest of the body.

sensory; motor

As a result of a neurotransmitter opening up chemically gated sodium channels on the postsynaptic membrane,

sodium ions enter the cell.

A typical synapse in the CNS consists of a presynaptic neuron and a postsynaptic neuron, separated by a narrow space called the

synaptic cleft

If all the sodium leakage channels were removed from the cell membrane of a neuron,

the membrane potential would be about -90 millivolts.

An excitatory postsynaptic potential (EPSP) causes

the postsynaptic neuron's membrane potential to become more positive. Correct

The negative value of the resting membrane potential means that

there are more negatively charged particles on the inside of the membrane than on the outside.

A regenerating axon in the PNS is guided by the regeneration tube and grows at a rate of about 5 millimeters per day.

true

After its synthesis in a neuron, acetylcholine is stored in synaptic vesicles within the synaptic knob.

true

Axoplasmic flow is an example of slow axonal transport.

true

Fast retrograde transport returns used synaptic vesicles and other materials to the soma and informs the soma of conditions at the axon terminals.

true

Neurotransmitters are removed from a synapse by degradation and reuptake.

true

On a typical neuron, the axon is usually longer in length than the dendrites.

true

Postsynaptic neurons can generate both inhibitory and excitatory postsynaptic potentials simultaneously.

true

Sodium has a higher concentration outside the cell than within.

true

The entry of sodium ions into the postsynaptic neuron causes depolarization.

true

The enzyme acetylcholinesterase, located in the synaptic cleft and on the postsynaptic membrane, breaks ACh down into acetate and choline, thereby stopping the stimulation of a postsynaptic cell.

true

An inhibitory postsynaptic potential (IPSP)

will make it more difficult for the postsynpatic neuron to reach threshold.