Question 1

Responses made possible by motor signals transmitted by the parasympathetic nervous system tend to be displayed throughout the body simultaneously because there is much divergence of nerve pathways and close anatomical association between presynaptic neurons and their ganglia as well as accessory activity with the adrenal glands.

Accepted Answer

The answer of Responses made possible by motor signals transmitted...

Question 2

Preganglionic fibers of the parasympathetic division of the autonomic nervous system leave the CNS at the level of the brainstem and sacral portions of the spinal cord.

Accepted Answer

This statement is true. Preganglionic fibers of the parasympathetic division originate from the brainstem and sacral regions of the spinal cord.

Question 3

Although nerve cells in each cerebral hemisphere make connections with other cells in the same hemisphere,there is no crossover of information between the two hemispheres.

Accepted Answer

There is crossover of information between the two hemispheres through a bundle of nerve fibers called the corpus callosum.

Question 4

Catecholamines are the most abundant neurotransmitters in the CNS.

Accepted Answer

While catecholamines (such as dopamine, norepinephrine, and epinephrine) are important neurotransmitters in the CNS, they are not the most abundant. Other neurotransmitters such as glutamate and GABA are more abundant.

Question 5

SNARE receptor protein complexes in presynaptic neurons function as inhibitors of calcium transport to dampen or reduce the amount of neurotransmitter vesicles which participate in exocytosis.

Accepted Answer

SNARE receptor protein complexes in presynaptic neurons facilitate calcium transport to promote the exocytosis of neurotransmitter vesicles, rather than inhibit it.

Question 6

The most common neurotransmitters for neuroeffector communication are dopamine and acetylcholine.

Accepted Answer

While dopamine and acetylcholine are important neurotransmitters, they are not the most common for neuroeffector communication. The most common neurotransmitter for neuroeffector communication is actually acetylcholine, followed by norepinephrine and dopamine.

Question 7

The frequency of action potentials in a postsynaptic cell is directly related to the degree of depolarization of the postsynaptic cell.

Accepted Answer

The frequency of action potentials in a postsynaptic cell is directly proportional to the degree of depolarization of the postsynaptic cell. As the cell becomes more depolarized, the frequency of action potentials increases, and as it becomes less depolarized, the frequency of action potentials decreases. This relationship is essential for transmitting signals from one neuron to another and is a fundamental principle of synaptic transmission in the nervous system.

Question 8

Most of the parasympathetic ganglia lie in chains along the spinal cord called sympathetic trunks.

Accepted Answer

The statement is describing sympathetic ganglia, not parasympathetic ganglia. Parasympathetic ganglia are usually located near or within the targeted organs.

Question 9

The action potential elicited by a supra-threshold stimulus is larger than one elicited by a threshold stimulus.

Accepted Answer

The magnitude of an action potential is not affected by the size of the stimulus; as long as the stimulus reaches the threshold, the action potential will always have the same magnitude due to the all-or-none principle.

Question 10

Opioid drugs,such as morphine,are agonists of a class of neurotransmitters called endorphins.

Accepted Answer

Opioid drugs bind to the same receptors in the brain that endorphins do, and they mimic the effects of endorphins by activating the same brain reward pathways. Therefore, they are considered agonists of endorphins.

Question 11

The Na⁺ and K⁺ channels that open during an action potential are voltage regulated,both opening in response to depolarization of the membrane.

Accepted Answer

These channels are indeed voltage regulated and open in response to depolarization of the membrane.

Question 12

The basal ganglia are important subcortical nuclei in the cerebrum.

Accepted Answer

The statement is true. The basal ganglia are a group of subcortical nuclei in the cerebrum that are involved in a variety of functions such as motor control, decision-making, and emotion regulation.

Question 13

The thalamus is the single most important control area for regulating the homeostasis of the internal environment.

Accepted Answer

While the thalamus is an important area in the brain, the hypothalamus is actually the main control center for regulating internal homeostasis. The hypothalamus is responsible for regulating body temperature, hunger and thirst, sleep, and various hormone productions.

Question 14

The efferent division of the peripheral nervous system consists of the somatic nervous system and the autonomic nervous system.

Accepted Answer

The efferent division of the peripheral nervous system includes both the somatic nervous system, which controls voluntary movements of skeletal muscles, and the autonomic nervous system, which controls involuntary actions such as heart rate, digestion, and breathing.

Question 15

The absolute refractory period of an excitable membrane roughly corresponds to the period when sodium channels are opening and inactivated.

Accepted Answer

During the absolute refractory period, sodium channels are opening and then quickly inactivating, preventing the depolarization of the membrane and making it unable to respond to another stimulus. This period lasts until the sodium channels fully recover from inactivation, which roughly corresponds to the end of the absolute refractory period.

Question 16

Because all parts of a neuronal cell body have the same threshold,no one synapse on the cell is more important than any other.

Accepted Answer

Different synapses on the same neuron can have different strengths and can contribute differently to the overall activity and firing of the neuron. This is known as synaptic plasticity and is a fundamental mechanism underlying learning and memory. Therefore, not all synapses on a neuron have the same significance or importance.

Question 17

The cerebrum consists only of gray matter.

Accepted Answer

The cerebrum consists of both gray and white matter.

Question 18

The relative refractory period of an excitable membrane refers to the period of time during which no stimulus,however strong,will elicit a second action potential in the membrane.

Accepted Answer

The relative refractory period is the period of time during which a stronger-than-threshold stimulus can generate an action potential.

Question 19

Dorsal root ganglia contain the cell bodies of efferent neurons.

Accepted Answer

Dorsal root ganglia contain the cell bodies of sensory (afferent) neurons, not efferent neurons. Efferent neurons have their cell bodies in the spinal cord or other parts of the central nervous system.

Question 20

Spinal nerves are composed of the axons of both afferent and efferent neurons.

Accepted Answer

Spinal nerves consist of both afferent and efferent neurons. Afferent neurons transmit sensory information from the peripheral sensory receptors to the spinal cord while efferent neurons transmit motor information from the spinal cord to the peripheral effectors, such as muscles or glands.

Quiz 6: Neuronal Signaling and the Structure of the Nervous System