Question 1

A stimulus traveling toward a synapse appears to open calcium ion channels at the presynaptic end,which in turn promotes fusion of synaptic vesicles to the axonal membrane.

Accepted Answer

This is true. The entry of calcium ions into the presynaptic terminal triggers the exocytosis of neurotransmitter-containing vesicles, which release their contents into the synaptic cleft.

Question 2

The action potential is caused by permeability changes in the plasma membrane.

Accepted Answer

The opening and closing of ion channels in the plasma membrane causes changes in permeability, which trigger the depolarization and repolarization phases of the action potential.

Question 3

Cell bodies of sensory neurons may be located in ganglia lying outside the central nervous system.

Accepted Answer

This is true. Sensory neurons may have cell bodies located in clusters of neurons called ganglia, which can be found outside the central nervous system. For example, the cell bodies of sensory neurons involved in touch and pain sensations in the limbs are located in dorsal root ganglia, which lie outside the spinal cord.

Question 4

A postsynaptic potential is a graded potential that is the result of a neurotransmitter released into the synapse between two neurons.

Accepted Answer

A postsynaptic potential is indeed a graded potential that occurs in response to the release of a neurotransmitter into the synapse between two neurons.

Question 5

In myelinated axons the voltage-regulated sodium channels are concentrated at the nodes of Ranvier.

Accepted Answer

This is because myelin provides insulation, preventing the spread of action potentials along the axon. The nodes of Ranvier are the gaps between the myelin sheaths where the action potential can be regenerated, and therefore they are where the voltage-regulated sodium channels are concentrated.

Question 6

Strong stimuli cause the amplitude of action potentials generated to increase.

Accepted Answer

The amplitude of action potentials does not vary with the strength of the stimulus; rather, it is the frequency of action potentials that increases with stronger stimuli.

Question 7

Nerve impulses are sent to slow the heart's rate of contraction.The nerve fibers sending these signals will most likely belong to which division of the nervous system?

Accepted Answer

The parasympathetic division is responsible for slowing the heart rate and is often referred to as the "rest and digest" division.

Question 8

The concentration neurotransmitters in the fluid of the synaptic cleft must be tightly regulated for neurons to function properly.Which of the following cells is most responsible for aiding in this regulation?

Accepted Answer

Astrocytes are a type of glial cell in the central nervous system that are involved in regulating the concentration of neurotransmitters in the synaptic cleft. They take up excess neurotransmitter molecules from the synaptic cleft and release them back to neurons when needed. This helps to maintain the proper balance of neurotransmitters for normal neuronal function. Satellite cells are found in the peripheral nervous system and support ganglia function. Schwann cells are responsible for myelination in the peripheral nervous system. Oligodendrocytes are responsible for myelination in the central nervous system.

Question 9

Reflexes are rapid,automatic responses to stimuli that will produce the same effect every time.

Accepted Answer

This is the definition of reflexes. They are involuntary and occur without conscious thought or decision-making.

Question 10

The all-or-none phenomenon as applied to nerve conduction states that the whole nerve cell must be stimulated for conduction to take place.

Accepted Answer

The all-or-none phenomenon refers to the principle that once a nerve impulse is initiated, it will travel along the neuron all the way to the end without decreasing in strength, but it does not require the whole nerve cell to be stimulated for conduction to take place; rather, it requires reaching a certain threshold of stimulation at the trigger zone.

Question 11

Unipolar neurons have axons structurally divided into peripheral and central processes.

Accepted Answer

Unipolar neurons have a single process that divides into two branches, one containing dendrites and the other an axon. The axon is further divided into a peripheral process that extends towards the periphery and a central process that extends towards the central nervous system.

Question 12

The concentration of ions in the chemical environment surrounding the neurons must be tightly regulated for neurons to function properly.Which of the following cells is most responsible for this?

Accepted Answer

Astrocytes are the most responsible cells for regulating ion concentration in the chemical environment surrounding the neurons. These cells maintain the optimal ionic balance by removing excess ions and recycling neurotransmitters.

Question 13

Cranial nerve II,the optic nerve sends nerve impulses to the brain carrying information about the things we see.These nerve fibers most likely belong to which division of the nervous system?

Accepted Answer

The optic nerve is responsible for transmitting sensory information from the eyes to the brain, making it a part of the sensory (afferent) division of the nervous system. The somatic nervous system is responsible for voluntary control of skeletal muscles, while the sympathetic and parasympathetic divisions are both part of the autonomic nervous system, which controls involuntary processes such as heart rate and digestion.

Question 14

During depolarization,the inside of the neuron's membrane becomes less negative.

Accepted Answer

During depolarization, the membrane potential becomes less negative, which can lead to the generation of an action potential.

Question 15

Nerve impulses leading to the skeletal muscle carry information to direct movement.The nerve fibers sending these signals will most likely belong to which division of the nervous system?

Accepted Answer

The somatic nervous system is responsible for carrying signals to skeletal muscles to direct movement. The sensory division carries signals from sensory receptors to the central nervous system, while the sympathetic and parasympathetic divisions are involved in the autonomic nervous system and control functions such as heart rate, digestion, and respiration.

Question 16

Enkephalins and endorphins are peptides that act like morphine.

Accepted Answer

Enkephalins and endorphins are both types of opioids that bind to the same receptors as morphine, producing analgesic and euphoric effects.

Question 17

Bacteria in the blood can be prevented entry to the fluids surrounding the brain.Which cells are most responsible for preventing bacteria from entering the fluids of the brain?

Accepted Answer

Astrocytes are a type of glial cell that play a crucial role in the blood-brain barrier. They form tight junctions with the cells lining the blood vessels in the brain, preventing bacteria from passing through into the cerebrospinal fluid that surrounds the brain. Satellite cells are found in peripheral nervous tissue and are not involved in the blood-brain barrier. Schwann cells and oligodendrocytes are responsible for myelination in the peripheral and central nervous systems respectively, and are not involved in preventing bacteria from entering the brain fluids.

Question 18

Nerve impulses leading to the brain carry information about cool temperatures on the skin.The nerve fibers sending these signals will most likely belong to which division of the nervous system?

Accepted Answer

Sensory (afferent) division of the nervous system is responsible for carrying sensory information from receptors to the central nervous system (brain and spinal cord). Cool temperatures on the skin are detected by sensory receptors and nerve impulses are sent through the sensory neurons to the brain for processing. The somatic nervous system is responsible for voluntary movements and controlling skeletal muscles, and is not directly involved in the perception of cool temperatures. The sympathetic and parasympathetic divisions of the autonomic nervous system are responsible for regulating involuntary bodily functions, such as heart rate and digestion, and are not directly involved in the perception of cool temperatures on the skin.

Question 19

Axon diameter and degree of myelination determine nerve impulse conduction velocity.

Accepted Answer

Axon diameter and degree of myelination have a direct impact on nerve impulse conduction velocity. Larger diameter axons and higher levels of myelination result in faster conduction velocities.

Question 20

Neurons in the CNS are organized into functional groups.

Accepted Answer

Neurons in the CNS are organized into functional groups such as sensory neurons, motor neurons, and interneurons.

Quiz 11: Fundamentals of the Nervous System and Nervous Tissue