The part of the peripheral nervous system that carries sensory information to the CNS is designated
Most CNS neurons lack centrioles. This observation explains
D) why CNS neurons cannot divide to regenerate damaged tissue.
Which of the following is a type of glial cell found in the peripheral nervous system?
A) satellite cells
The largest and most numerous of the glial cells in the central nervous system are the
Functions of astrocytes include all of the following:
-responding to neural tissue damage
-maintaining the blood-brain barrier
-forming a three-dimensional framework for the CNS
-guiding neuron development
except conduct action potential D
Many medications introduced into the bloodstream cannot directly affect the neurons of the CNS because
C) the endothelium of CNS capillaries forms a blood-brain barrier.
Extensive damage to oligodendrocytes in the CNS could result in
B) loss of sensation and motor control.
Which of the following is NOT involved in the establishment of a neuron's resting potential?
Electrical forces push sodium ions out of the cell.
The sodium-potassium ion exchange pump
E) moves sodium and potassium opposite to the direction of their electrochemical gradients.
If the permeability of a resting axon to sodium ion increases,
B) inward movement of sodium will increase and the membrane will depolarize.
If the potassium permeability of a resting neuron increases above the resting permeability, what effect will this have on the transmembrane potential?
A) The inside of the membrane will become more negative.
If acetylcholine (ACh) causes inhibition of a postsynaptic neuron, to what type of membrane channel did the ACh bind?
E) chemically-regulated potassium channel
A stimulus that changes a neuron membrane potential from the resting -75 mV to -85 mV is:
B) an inhibitory stimulus
If the axolemma becomes more permeable to potassium ion:
a stronger stimulus will be required to cause an action potential
Main steps in the generation of an action potential.
1. A graded depolarization brings an area of an excitable membrane to threshold.
2. Sodium channel activation occurs.
3. Sodium ions enter the cell and depolarization occurs.
4. Sodium channels are inactivated.
5. Potassium channels open and potassium moves out of the cell, initiating repolarization.
6. Sodium channels regain their normal properties.
7. A temporary hyperpolarization occurs.
The all-or-none principle states that
B) all stimuli great enough to bring the membrane to threshold will produce identical action potentials.
The same ________ can have different effects depending on the properties of the ________.
E) neurotransmitter; receptor
Which of the following statements about the action potential is false?
A) The rapid depolarization phase is caused by the entry of potassium ions.
B) Repolarization occurs as potassium ions leave the axon.
C) In the after-hyperpolarization phase, membrane potential approaches the potassium equilibrium potential.
D) During the repolarization phase, sodium channels close and potassium channels open.
E) During the depolarization phase, membrane potential becomes positive.
The rapid depolarization phase is caused by the entry of potassium ions.
How would a chemical that prevents the opening of voltage-regulated Na+ channels affect the function of a neuron?
neuron will only be capable of producing graded potentials
Puffer fish poison blocks voltage-gated sodium channels like a cork. What effect would this neurotoxin have on the function of neurons?
A) The axon would be unable to generate action potentials.
In what would the rate of impulse conduction be the greatest?
C) a myelinated fiber of 10-μm diameter
The steps involved in transmission at a cholinergic synapse: C) 4,2,6,7,1,8,3,5.
4. An action potential depolarizes the synaptic terminal at the presynaptic membrane.
2. Calcium ions enter the synaptic terminal.
6. Acetylcholine is released from storage vesicles by exocytosis.
7. Acetylcholine binds to receptors on the postsynaptic membrane.
1. Chemically-gated sodium channels on the postsynaptic membrane are activated.
8. Calcium ions are removed from the cytoplasm of the synaptic terminal.
3. Acetylcholinesterase hydrolyzes acetylcholine.
5. The synaptic terminal reabsorbs choline.
If the chemically-gated sodium channels in the postsynaptic membrane were completely blocked,
C) synaptic transmission would fail.
The effect that a neurotransmitter has on the postsynaptic membrane depends on:
-the frequency of neurotransmitter release
-the quantity of neurotransmitters released.
-the nature of the neurotransmitter.
-the characteristics of the receptors.
Each of the following is an example of a neuroeffector junction, except the junction between a neuron and a(n)
A) nerve cell.
B) exocrine gland cell.
C) smooth muscle cell.
D) endocrine gland cell.
E) skeletal muscle cell.
nerve cell. a)
What triggers the release of acetylcholine from a synaptic terminal?
E) diffusion of calcium ions into the synaptic terminal
A postsynaptic neuron will have an Excitatory Postsynaptic Potential (EPSP) when
A) chemically-regulated sodium channels are open and sodium is diffusing into the cell.
When a second EPSP arrives at a single synapse before the effects of the first have disappeared, what occurs?
B) temporal summation
Summation that results from the cumulative effect of multiple synapses at multiple places on the neuron is designated
D) spatial summation.
Samples of CSF for diagnostic purposes are normally obtained by placing the tip of a needle in the
D) subarachnoid space.
In the spinal cord, white matter is separated into ascending and descending tracts organized as
Axons crossing from one side of the spinal cord to the other within the gray matter are found in the?
E) gray commissures.
The white matter of the spinal cord contains?
B) bundles of axons with common origins, destinations, and functions.
Postganglionic fibers of the autonomic nervous system that innervate internal organs do not rejoin the spinal nerve but form
B) sympathetic nerves.
The layer of connective tissue that surrounds a fascicle within a peripheral nerve is the
A viral disease that destroys the cells of the anterior gray horn will
lead to skeletal muscle weakness or paralysis.
The complex, interwoven network formed by contributions from the ventral rami of neighboring spinal nerves is termed a(n)
Each of the following nerves originates in the lumbar plexus, except the ________ nerve.
The layer of connective tissue that surrounds individual axons within a peripheral nerve is termed the
If a person has a crush injury to the C3-C5 spinal segments, you would expect that he
might be unable to breathe on his own.
Which nerve approaches the knee, than divides into two branches, the fibular nerve and the tibial nerve.
The brachial plexus gives rise to all of the following nerves?
Recognized neuronal circuit patterns include:
- parallel processing.
What are neural reflexes functions?
- are the simplest form of behavior.
- are automatic motor responses.
- help preserve homeostasis.
- involve at least two neurons.
EXCEPT cannot be modified by the brain.
Reflexes can be classified by:
- where information processing occurs.
- the motor response.
- their development.
- the complexity of the neural circuit.
EXCEPT whether they are sensory or motor.
All of the following are true of muscle spindles, except that they
EXCEPT found in tendons.
-consist of specialized fibers called intrafusal fibers.
- are the receptor for the stretch reflex.
- are found within skeletal muscle.
- are innervated by gamma motor neurons.
Neurons in which dendritic and axonal processes are continuous and the soma lies of to one side are called?