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.