MSN Exam for Neurological System Part II

Text Mode – Text version of the exam

Questions

1. In the hustle and bustle of Ward 6, Nurse Parker is diligently caring for a newly admitted patient, Mr. Mason, who is diagnosed with an unusual autoimmune condition, Myasthenia Gravis. She recalls from her training that the disorder is characterized by the impairment and destruction of certain types of receptors by rogue antibodies, but which ones?

A. Receptors responsive to nicotine.
B. Acetylcholine-targeting receptors.
C. Transient receptors.
D. Receptors designed for epinephrine.

2. Within the confines of a busy hospital, Nurse Sullivan is consulting a neuroscience textbook, brushing up on her knowledge of specialized neural cells. She comes across a term, ‘Oligodendrocytes’, and tries to recollect where these cells reside.

A. Peripheral Nervous System (PNS)
B. Central Nervous System (CNS)

3. During her afternoon rounds in the neurological ward, Nurse Thompson ponders the vast complexity of the human brain. She considers the multitude of amino acids, some of which have an additional role in the Central Nervous System (CNS) as neurotransmitters. She wonders, which among these amino acids can act in such a way?

A. Leucine
B. Glutamic acid
C. Valine
D. Lysine

4. Nurse Bennett, specialized in neurology, is providing care to Mrs. Douglas, a patient diagnosed with Huntington’s chorea, a genetic neurological disorder. In his clinical review, he recalls that this condition is associated with a deficiency in a particular amino acid, but which one?

A. L-lysine
B. L-tyrosine
C. Gamma-aminobutyric acid (GABA)
D. L-valine

5. In the middle of a hectic shift in the psychiatric unit, Nurse Garcia is revisiting her knowledge about monoamines, neurotransmitters playing crucial roles in mood regulation. Among the choices below, she is trying to identify the compound that doesn’t belong to the monoamine group.

A. Norepinephrine
B. Dopamine
C. Epinephrine
D. Adenosine

6. On a late-night shift in the neurology department, Nurse Mitchell is reflecting on her knowledge of catecholamines, a specific group of neurotransmitters. She is trying to identify the outlier among the following compounds – one that is not classified as a catecholamine.

A. Dopamine
B. Norepinephrine
C. Epinephrine
D. Serotonin

7. In the neurology department, Nurse Roberts is monitoring a patient suffering from seizures. Reflecting on the mechanism of the medication she just administered, she remembers that GABA promotes hyperpolarization by triggering the opening of specific ion channels. But which ones?

A. Sodium (Na+)
B. Calcium (Ca++)
C. Chloride (Cl-)
D. Potassium (K+)

8. As part of the night shift in the emergency department, Nurse Anderson is handling a case of severe anxiety. She administers Valium, a medication known to dampen neural communication. She reflects on which neurotransmitter this drug primarily influences.

A. Norepinephrine
B. Epinephrine
C. Dopamine
D. GABA

9. On a busy afternoon in the psychiatric ward, Nurse Williams is caring for a patient with depression. The prescribed medication for the patient functions by hindering the reabsorption of serotonin into presynaptic neurons. She ponders, which drug accomplishes this effect?

A. Xanax
B. Valium
C. Deprenyl
D. Prozac

10. In the neurological ward, Nurse Patterson is observing a patient suffering from a disorder affecting the ventricles and spinal cord. She remembers from her training that a specific type of cell lines these areas. But which ones are they?

A. Oligodendrocytes
B. Astrocytes
C. Ependymal cells
D. Schwann cells

11. In the emergency room, Nurse Hamilton encounters a case of suspected poisoning. She recalls that certain toxins can block the sodium channels, disrupting normal neurological function. She wonders, which toxin is known for this specific effect?

A. Strychnine
B. Curare
C. Neostigmine
D. Tetrodotoxin

12. In the infectious disease ward, Nurse Ramirez is caring for a patient diagnosed with botulism, caused by the bacterium Clostridium botulinum. She remembers that this bacterium releases a particular enzyme wreaking havoc on peptide bonds. What is this enzyme?

A. Endopeptidases
B. Exopeptidases
C. Amylase
D. Protein kinase

13. Nurse Campbell is providing care to Mr. Watson, who has recently been diagnosed with multiple sclerosis (MS), a disease that targets a specific component of neurons in the Central Nervous System (CNS). She is trying to remember the exact neural component under attack. Is it the:

A. Axon terminals
B. Myelin sheaths
C. Nicotinic receptors
D. Sodium channels

14. Nurse Roberts, while working in the neurology department, is reviewing her knowledge about different types of glial cells. One particular cell type, the Schwann cells, comes to her mind. She knows they reside in a specific part of the nervous system, but which one?

A. Peripheral Nervous System (PNS)
B. Central Nervous System (CNS)

15. Amid her night shift in the neurology ward, Nurse Hudson is studying different types of synapses. Among the following options, she’s attempting to pick out the one that is not recognized as a type of synapse.

A. Axon-to-axon junction.
B. Axon-to-cell body linkage.
C. Dendrite-to-axon connection.
D. Dendrite-to-dendrite interaction.

16. During her rounds in the neurological ward, Nurse Turner reflects on the myriad cell types within the Central Nervous System (CNS). Among these diverse cell types, she tries to recall which one is the most prevalent.

A. Celiac cells
B. Neurocytes
C. Oligocytes
D. Astrocytes

17. While working in the neurology department, Nurse Martin is reviewing the fundamentals of neural signaling. She knows that the specific manner in which a nerve impulse travels through the nodes of Ranvier has a particular name. But what is it?

A. Conduction along uncoated segments.
B. Relative conduction.
C. Saltatory conduction.
D. Simple transmission.

18. Nurse Thompson, in the neurology department, is reflecting on the numerous support cells found within the Central Nervous System (CNS). She remembers there’s a collective term for these cells. What is it?

A. Neuroglia
B. Star cells
C. Cell body cells
D. Orbiting cells

Answers and Rationales

1. Correct answer:

B. Acetylcholine-targeting receptors. Myasthenia Gravis is an autoimmune disorder where the body’s immune system mistakenly attacks its own tissues. In this case, the tissues under attack are the acetylcholine receptors located at the neuromuscular junction. Acetylcholine is a neurotransmitter, a chemical messenger that transmits signals across a chemical synapse, such as a neuromuscular junction. In a healthy body, acetylcholine binds to these receptors, triggering muscle contraction. However, in Myasthenia Gravis, antibodies block, alter, or destroy these receptors, which prevents the muscle cells from receiving messages (neurotransmitters) from the nerve cell. This results in muscle weakness and fatigue.

Imagine the neuromuscular junction as a mailbox (the receptor) and the mailman (the nerve) delivering letters (acetylcholine). In Myasthenia Gravis, it’s as if someone is blocking the mailbox or destroying it, preventing the letters from being delivered and read.

Incorrect answer options:

A. Receptors responsive to nicotine. While it’s true that acetylcholine receptors can also be responsive to nicotine (hence they are sometimes referred to as nicotinic acetylcholine receptors), the term “nicotine-responsive receptors” could be misleading. Not all receptors responsive to nicotine are involved in Myasthenia Gravis. The disorder specifically targets acetylcholine receptors at the neuromuscular junction.

C. Transient receptors. Transient receptor potential channels (TRP channels) are a group of ion channels located mostly on the plasma membrane of numerous animal cell types. These are not the primary receptors involved in Myasthenia Gravis.

D. Receptors designed for epinephrine. Epinephrine, also known as adrenaline, has its own set of receptors called adrenergic receptors. These receptors are not the primary targets in Myasthenia Gravis.

2. Correct answer:

B. Central Nervous System (CNS). Oligodendrocytes are a type of glial cell that reside in the central nervous system (CNS), which includes the brain and spinal cord. Their primary function is to produce myelin, a fatty substance that wraps around the axons of neurons, forming an insulating layer known as the myelin sheath. This myelination process is crucial for the rapid transmission of electrical signals along the nerve cells, enhancing the efficiency of communication within the nervous system.

Think of the axons as electrical wires and the myelin sheath as the plastic insulation around the wires. Just as the insulation prevents electrical signals from leaking out of the wires, the myelin sheath prevents signal loss from the axons, ensuring that the signals reach their intended destination quickly and accurately.

Incorrect answer option:

A. Peripheral Nervous System (PNS). While the peripheral nervous system (PNS) also contains myelinated neurons, the myelin in the PNS is produced by a different type of glial cell called Schwann cells, not oligodendrocytes. The PNS includes all the nerves outside the brain and spinal cord that connect the CNS to the rest of the body. Although oligodendrocytes and Schwann cells perform similar functions in their respective systems, they are distinct in their location and structure.

3. Correct answer:

B. Glutamic acid. Glutamic acid, also known as glutamate, is an amino acid that plays a crucial role in the central nervous system (CNS) as the primary excitatory neurotransmitter. It is involved in various cognitive functions such as learning and memory. Glutamate works by binding to specific receptors on the neurons, leading to the opening of ion channels and causing an influx of positive ions into the neuron. This results in the excitation of the neuron, triggering an action potential that allows the signal to be transmitted to the next neuron.

Think of glutamate as a key and the neuron as a locked door. When the key (glutamate) fits into the lock (receptor), the door (ion channel) opens, allowing people (ions) to enter. This influx of people changes the environment inside the room (neuron), leading to a series of events (action potential) that eventually opens another door to the next room (next neuron).

Incorrect answer options:

A. Leucine
C. Valine
D. Lysine

Leucine, valine, and lysine are all essential amino acids, meaning they cannot be synthesized by the body and must be obtained through the diet. While they are crucial for protein synthesis and various metabolic processes, they do not act as neurotransmitters in the CNS. Their primary roles are in muscle development and repair, energy production, and other metabolic processes.

4. Correct answer:

C. GABA. Huntington’s chorea, also known as Huntington’s disease, is a genetic disorder that causes progressive degeneration of nerve cells in the brain. This condition is associated with a deficiency in the neurotransmitter gamma-aminobutyric acid (GABA). GABA is an amino acid that acts as the primary inhibitory neurotransmitter in the central nervous system (CNS). It works by decreasing neuronal excitability, thus regulating muscle tone and preventing excessive activity in the nervous system.

In the context of Huntington’s disease, the deficiency in GABA leads to a lack of inhibitory control over muscle movement, resulting in the characteristic involuntary, jerky movements (chorea) seen in patients with this condition.

Think of GABA as the brakes on a car. Just as the brakes control the speed of the car and prevent it from going too fast, GABA controls the activity of neurons and prevents them from firing too rapidly. In Huntington’s disease, the lack of GABA is like having faulty brakes, leading to uncontrolled neuronal activity and, consequently, uncontrolled muscle movements.

Incorrect answer options:

A. Lysine
B. Tyrosine
D. Valine

Lysine, tyrosine, and valine are all amino acids, but they do not play a direct role in the pathophysiology of Huntington’s disease. While they are important for various metabolic processes and protein synthesis, they are not associated with the characteristic symptoms of Huntington’s disease.

5. Correct answer:

D. Adenosine. Adenosine is a purine nucleoside composed of a molecule of adenine attached to a ribose sugar molecule (ribofuranose) moiety via a β-N9-glycosidic bond. It plays an important role in energy transfer as adenosine triphosphate (ATP) and adenosine diphosphate (ADP), as well as in signal transduction as cyclic adenosine monophosphate (cAMP). It is also a neuromodulator, believed to play a role in promoting sleep and suppressing arousal. However, it is not classified as a monoamine neurotransmitter.

Monoamine neurotransmitters are neurotransmitters and neuromodulators that contain one amino group that is connected to an aromatic ring by a two-carbon chain (-CH2-CH2-). Examples of monoamines include dopamine, norepinephrine, and epinephrine.

Think of neurotransmitters as keys and the receptors in the brain as locks. Monoamines are a specific type of key that can open certain locks, while adenosine is a different type of key that opens different locks.

Incorrect answer options:

A. Norepinephrine. Norepinephrine is a monoamine neurotransmitter. It is synthesized from dopamine by the enzyme dopamine β-hydroxylase. It functions in the brain and body to regulate heart rate, blood pressure, and blood glucose levels. It is also involved in the body’s response to stress.

B. Dopamine. Dopamine is a monoamine neurotransmitter. It is synthesized in the brain and kidneys. Dopamine is involved in several functions in the brain, including motor control, reward, and regulation of mood.

C. Epinephrine. Epinephrine, also known as adrenaline, is a monoamine neurotransmitter and hormone. It is synthesized from norepinephrine and is involved in the body’s response to stress or danger. It increases heart rate, blood pressure, and blood glucose levels.

6. Correct answer:

D. Serotonin. Serotonin, also known as 5-hydroxytryptamine (5-HT), is a monoamine neurotransmitter derived from tryptophan. It is primarily found in the gastrointestinal tract, blood platelets, and the central nervous system of animals and humans. It is well known for contributing to feelings of well-being and happiness. However, it is not classified as a catecholamine.

Catecholamines are a group of neurotransmitters that include dopamine, norepinephrine, and epinephrine. They are called catecholamines because they contain a catechol group (a benzene ring with two hydroxyl side groups) and an amine (nitrogen-containing) group.

Think of neurotransmitters as different types of fuel for various vehicles. Catecholamines could be likened to gasoline, powering specific types of vehicles (or, in this case, transmitting signals in certain pathways in the brain). Serotonin, on the other hand, is more like diesel fuel. It’s a different type of fuel, used by different types of vehicles (or different pathways in the brain).

Incorrect answer options:

A. Dopamine. Dopamine is a catecholamine. It is synthesized in the brain and kidneys and is involved in several functions in the brain, including motor control, reward, and regulation of mood.

B. Norepinephrine. Norepinephrine is a catecholamine. It is synthesized from dopamine by the enzyme dopamine β-hydroxylase. It functions in the brain and body to regulate heart rate, blood pressure, and blood glucose levels. It is also involved in the body’s response to stress.

C. Epinephrine. Epinephrine, also known as adrenaline, is a catecholamine. It is synthesized from norepinephrine and is involved in the body’s response to stress or danger. It increases heart rate, blood pressure, and blood glucose levels.

7. Correct answer:

C. Chloride (Cl-). Gamma-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the central nervous system. It works by binding to GABA receptors, which are ligand-gated ion channels. When GABA binds to these receptors, the channels open and allow chloride ions (Cl-) to enter the neuron. This influx of negatively charged chloride ions makes the inside of the neuron more negative (or hyperpolarized), which makes it less likely to fire an action potential.

Think of the neuron as a party and the action potentials as the noise level. GABA is like a party-goer who turns down the music (lets in chloride ions), making it less likely that the neighbors (other neurons) will hear the noise (fire an action potential).

Incorrect answer options:

A. Sodium (Na+). Sodium ions are involved in the depolarization phase of the action potential. When sodium channels open, sodium ions rush into the neuron, making the inside more positive and triggering an action potential. This is the opposite of what GABA does.

B. Calcium (Ca++). Calcium ions play a key role in the release of neurotransmitters at the synapse. When an action potential reaches the end of a neuron, it triggers the opening of calcium channels, and the influx of calcium ions prompts the release of neurotransmitters into the synapse. However, calcium ions are not directly involved in the hyperpolarizing effect of GABA.

D. Potassium (K+). Potassium ions are involved in the repolarization phase of the action potential. After the neuron fires, potassium channels open to allow potassium ions to leave the neuron, which helps return the neuron to its resting state. While this does make the inside of the neuron more negative, it is not the mechanism by which GABA induces hyperpolarization.

8. Correct answer:

D. GABA. Valium, also known as diazepam, is a medication that belongs to the benzodiazepine class of drugs. It primarily influences the neurotransmitter gamma-aminobutyric acid (GABA). GABA is the main inhibitory neurotransmitter in the central nervous system. It works to slow down the activity of nerve cells in the brain, leading to effects such as reduced anxiety, relaxation of muscles, and sleepiness.

Benzodiazepines like Valium enhance the effect of GABA. They bind to a specific site on the GABA receptor and increase the frequency of chloride channel opening. This allows more chloride ions to enter the neuron, which further hyperpolarizes the neuron and makes it even less likely to fire an action potential. This leads to an overall decrease in brain activity, which can help to reduce symptoms of anxiety.

Think of GABA as the brakes of a car and the neurons as the car itself. Valium essentially makes these brakes (GABA) more effective, allowing the car (neurons) to slow down more effectively, leading to a calming effect.

Incorrect answer options:

A. Norepinephrine. Norepinephrine is a neurotransmitter involved in the body’s response to stress. It is not the primary target of Valium.

B. Epinephrine. Epinephrine, also known as adrenaline, is a hormone and neurotransmitter involved in the body’s response to stress. It is not the primary target of Valium.

C. Dopamine. Dopamine is a neurotransmitter involved in reward and pleasure systems in the brain. While benzodiazepines may indirectly affect dopamine systems, dopamine is not the primary target of Valium.

9. Correct answer:

D. Prozac. Prozac, also known as fluoxetine, is a type of antidepressant medication in the selective serotonin reuptake inhibitor (SSRI) class. SSRIs work by blocking the reabsorption (reuptake) of serotonin into neurons. This makes more serotonin available to improve transmission of messages between neurons. SSRIs are a popular type of antidepressant because they generally have fewer side effects than other types of antidepressants.

Think of serotonin as money, neurons as banks, and the synapse as the economy. In depression, it’s as if there isn’t enough money (serotonin) in the economy (synapse) to keep things running smoothly. Prozac works like a law that prevents banks (neurons) from taking money (serotonin) out of the economy (synapse), which helps to boost the economy (improve mood).

Incorrect answer options:

A. Xanax. Xanax, also known as alprazolam, is a benzodiazepine. It is primarily used to treat anxiety and panic disorders, and it works by enhancing the effect of the neurotransmitter GABA, not serotonin.

B. Valium. Valium, also known as diazepam, is another benzodiazepine. Like Xanax, it enhances the effect of GABA, not serotonin.

C. Deprenyl. Deprenyl, also known as selegiline, is a type of drug used to treat Parkinson’s disease. It works by inhibiting the activity of monoamine oxidase B, an enzyme that breaks down dopamine in the brain. It does not primarily affect serotonin reuptake.

10. Correct answer:

C. Ependymal cells. Ependymal cells are a type of glial cell and are responsible for lining the ventricles of the brain and the central canal of the spinal cord. They are involved in the production and regulation of cerebrospinal fluid (CSF), which bathes and cushions the brain and spinal cord.

Think of the brain and spinal cord as a delicate computer system. The ependymal cells would be like the cooling system that helps regulate temperature and prevent overheating (in this case, they help produce and regulate CSF to protect the brain and spinal cord).

Incorrect answer options:

A. Oligodendrocytes. Oligodendrocytes are a type of glial cell in the central nervous system that form the myelin sheath, which insulates nerve cell axons to increase the speed at which information (nerve impulses) is passed along the axon. They do not line the ventricles or the central canal of the spinal cord.

B. Astrocytes. Astrocytes are star-shaped glial cells in the brain and spinal cord. They perform many functions, including biochemical support of endothelial cells that form the blood–brain barrier, provision of nutrients to the nervous tissue, and maintenance of extracellular ion balance. They do not line the ventricles or the central canal of the spinal cord.

D. Schwann cells. Schwann cells are a variety of glial cell that keep peripheral nerve fibres (both myelinated and unmyelinated) alive. In myelinated axons, Schwann cells form the myelin sheath. The function of the myelin sheath is to allow electrical impulses to transmit quickly and efficiently along the nerve cells. They are not found in the brain or spinal cord, and thus do not line the ventricles or the central canal of the spinal cord.

11. Correct answer:

D. Tetrodotoxin. Tetrodotoxin is a potent neurotoxin that is known to block sodium channels. It is found in various marine animals, such as the pufferfish, blue-ringed octopus, and some species of newts and frogs. By blocking sodium channels, tetrodotoxin prevents the generation and conduction of action potentials, leading to symptoms such as numbness, paralysis, and in severe cases, death due to respiratory failure.

Think of the sodium channels as doors in a hallway, and the action potentials as people trying to get through those doors. Tetrodotoxin is like a barricade that prevents the doors from opening, so the people (action potentials) can’t get through.

Incorrect answer options:

A. Strychnine. Strychnine is a poison that acts as a central nervous system stimulant. It works by blocking the action of the inhibitory neurotransmitter glycine, leading to overstimulation of muscles.

B. Curare. Curare is a poison that causes paralysis by blocking the nicotinic acetylcholine receptor, which is a receptor for the neurotransmitter acetylcholine at the neuromuscular junction. This prevents the transmission of signals from nerves to muscles.

C. Neostigmine. Neostigmine is not a toxin, but a medication that is used to treat myasthenia gravis and to reverse the effects of non-depolarizing muscle relaxants. It works by inhibiting the action of acetylcholinesterase, an enzyme that breaks down acetylcholine in the synapse, thereby increasing the amount of acetylcholine available to stimulate muscle contraction.

12. Correct answer:

A. Endopeptidases. The bacterium Clostridium botulinum produces a neurotoxin known as botulinum toxin, which is one of the most potent toxins known. This toxin functions as a protease, a type of enzyme that breaks down proteins. More specifically, it is an endopeptidase, which means it cleaves peptide bonds within the protein chain. In the case of botulinum toxin, it cleaves proteins involved in the fusion of synaptic vesicles with the presynaptic membrane, thereby preventing the release of acetylcholine and causing paralysis.

Think of a protein as a string of Christmas lights. Each light bulb is like an amino acid, and the wire connecting them represents the peptide bonds. An endopeptidase is like a pair of scissors that can cut the wire (peptide bonds) anywhere along the string (protein), not just at the ends.

Incorrect answer options:

B. Exopeptidases. Exopeptidases are enzymes that cleave peptide bonds at the end of proteins, removing a single amino acid at a time. They do not target the internal peptide bonds like endopeptidases do.

C. Amylase. Amylase is an enzyme that breaks down starch into sugars. It is not involved in the action of botulinum toxin.

D. Protein kinase. Protein kinases are enzymes that modify proteins by adding a phosphate group to them, a process known as phosphorylation. They do not break peptide bonds like proteases do.

13. Correct answer:

B. Myelin sheaths. Multiple sclerosis (MS) is a chronic disease of the central nervous system in which the immune system mistakenly attacks the myelin sheaths that cover nerve fibers, causing communication problems between the brain and the rest of the body. Over time, the disease can cause the nerves themselves to deteriorate or become permanently damaged.

Think of the neurons as electrical wires and the myelin sheaths as the insulation around the wires. In MS, it’s as if the insulation is being stripped away, which disrupts the flow of electricity (or, in this case, the transmission of nerve impulses).

Incorrect answer options:

A. Axon terminals. While axon terminals are crucial for transmitting signals from one neuron to another, they are not the primary target in MS.

C. Nicotinic receptors. Nicotinic receptors are a type of receptor for the neurotransmitter acetylcholine. They are not the primary target in MS.

D. Sodium channels. Sodium channels play a crucial role in generating and conducting action potentials in neurons. While changes in sodium channel function can occur in MS as a result of demyelination, they are not the primary target of the immune attack in MS.

14. Correct answer:

A. Peripheral Nervous System (PNS). Schwann cells are a type of glial cell that reside in the peripheral nervous system. They play a crucial role in the maintenance and functioning of nerve fibers in the PNS. One of their main functions is to form the myelin sheath, a fatty layer that insulates nerve fibers and allows for efficient transmission of electrical signals along the nerve.

Think of the nerve fibers as electrical wires and the Schwann cells as the insulation around those wires. Just as the insulation around a wire prevents the electrical signal from leaking out, the myelin sheath formed by Schwann cells ensures that the electrical signals (nerve impulses) are transmitted efficiently along the nerve fiber.

Incorrect answer option:

B. Central Nervous System (CNS). The myelin sheath in the central nervous system is produced by a different type of glial cell called oligodendrocytes, not Schwann cells.

15. Correct answer:

C. Dendrite-to-axon connection. In the nervous system, synapses typically involve a connection between the axon of one neuron and the dendrite or cell body of another neuron. The term “dendrite-to-axon connection” is not recognized as a standard type of synapse. The more common types of synapses are axodendritic (axon to dendrite) and axosomatic (axon to cell body).

Think of neurons as people having a conversation. The axon is like the mouth of one person, and the dendrite or cell body is like the ear of another person. A dendrite-to-axon connection would be like one person trying to talk into the mouth of another person, which is not a typical way of communicating.

Incorrect answer options:

A. Axon-to-axon junction. This type of synapse, also known as an axoaxonic synapse, does exist, but it is less common and typically serves to modulate the activity of other synapses rather than directly transmit information.

B. Axon-to-cell body linkage. This is a type of synapse known as an axosomatic synapse. It involves a connection between the axon of one neuron and the cell body (soma) of another neuron.

D. Dendrite-to-dendrite interaction. This is a type of synapse known as a dendrodendritic synapse. It involves a connection between the dendrites of two neurons and can allow for bidirectional communication.

16. Correct answer:

D. Astrocytes. Astrocytes are the most abundant cell type within the Central Nervous System (CNS). These star-shaped glial cells perform a variety of functions, including biochemical support of endothelial cells that form the blood-brain barrier, provision of nutrients to nervous tissue, and maintenance of extracellular ion balance. They also play a role in the repair and scarring process of the brain and spinal cord following traumatic injuries.

Think of the CNS as a bustling city. The neurons are like the city’s residents, while the astrocytes are like the infrastructure and support services that keep the city running smoothly. Just as a city has more buildings and services than people, the CNS has more astrocytes than neurons.

Incorrect answer options:

A. Celiac cells. Celiac cells are not a recognized cell type within the CNS. The term “celiac” is more commonly associated with the celiac disease, which is an autoimmune disorder affecting the small intestine.

B. Neurocytes. While “neurocyte” is sometimes used as a general term for a nerve cell or neuron, neurons are not the most abundant cell type in the CNS. That distinction goes to the astrocytes.

C. Oligocytes. There is no recognized cell type called “oligocytes” in the CNS. The term may be a confusion with oligodendrocytes, which are a type of glial cell in the CNS that produce the myelin sheath around neuronal axons.

17. Correct answer:

C. Saltatory conduction. Saltatory conduction is the process by which action potentials in neurons are propagated along the axons with myelin sheaths. The action potential “jumps” from one node of Ranvier (gaps in the myelin sheath where the axon is exposed) to the next, rather than propagating along every part of the axon. This allows for faster transmission of the action potential along the axon.

Think of saltatory conduction as a kangaroo hopping along a path. The kangaroo (the action potential) doesn’t walk along the entire path (the axon); instead, it hops from one point (node of Ranvier) to the next, which allows it to travel faster.

Incorrect answer options:

A. Conduction along uncoated segments. This is not a recognized term in neuroscience. It may be a confusion with the concept of saltatory conduction, which involves conduction along the uncoated segments of the axon (the nodes of Ranvier).

B. Relative conduction. This is not a recognized term in neuroscience. Conduction of action potentials is not typically described as “relative.”

D. Simple transmission. This is not a recognized term in neuroscience. While action potentials do involve the transmission of information along the axon, this process is not typically described as “simple transmission.”

18. Correct answer:

A. Neuroglia. Neuroglia, also known simply as glia, are the support cells of the central nervous system. They provide various critical functions that help neurons to operate effectively. These functions include providing nutrients to neurons, maintaining the balance of ions in the extracellular environment, participating in the immune response, and forming the myelin sheath around axons.

Think of the CNS as a bustling city. The neurons are like the city’s residents, while the neuroglia are like the infrastructure and support services that keep the city running smoothly. Just as a city needs more than just people to function, the CNS needs more than just neurons to operate effectively.

Incorrect answer options:

B. Star cells. This is not a recognized term for the support cells in the CNS. The term may be a confusion with astrocytes, which are a type of glial cell. The name “astrocyte” comes from the Greek words for “star” and “cell,” reflecting their star-like shape.

C. Cell body cells. This is not a recognized term for the support cells in the CNS. The term “cell body” refers to the part of a neuron that contains the nucleus and most of the cell’s organelles.

D. Orbiting cells. This is not a recognized term for the support cells in the CNS.