Neurological System Part II (Practice Mode)- Www.Rnpedia.Com

Multiple sclerosis is a disease that attacks the myelin sheaths of neurons in the central nervous system (CNS). Myelin sheaths are protective coverings that surround and insulate nerve fibers, allowing for efficient transmission of electrical signals. When these myelin sheaths are damaged, communication between neurons is disrupted, leading to various neurological symptoms experienced by individuals with multiple sclerosis.

Myasthenia gravis is an autoimmune disorder where the body's own antibodies mistakenly attack and destroy acetylcholine receptors. Acetylcholine is a neurotransmitter that plays a crucial role in muscle contraction and communication between nerves and muscles. When the acetylcholine receptors are blocked and destroyed by these antibodies, it leads to muscle weakness and fatigue, which are characteristic symptoms of myasthenia gravis.

Oligodendrocytes are a type of glial cell that are responsible for producing myelin in the central nervous system (CNS). Myelin is a fatty substance that forms a protective sheath around nerve fibers, allowing for faster and more efficient transmission of electrical signals. Therefore, oligodendrocytes are specifically located in the CNS, where they play a crucial role in maintaining the proper functioning of nerve cells.

Adenosine is not considered a monoamine because it is not derived from an amino acid and does not contain an amine group. Monoamines are a class of neurotransmitters that are derived from amino acids and contain an amine group. Epinephrine, norepinephrine, and dopamine are all monoamines because they are derived from the amino acid tyrosine and contain an amine group. Adenosine, on the other hand, is a nucleoside that is not derived from an amino acid and does not contain an amine group, making it not considered a monoamine.

Glutamic acid can function as a neurotransmitter in the central nervous system (CNS). It is an excitatory neurotransmitter that plays a crucial role in synaptic transmission and the regulation of neuronal activity. Glutamic acid is involved in various physiological processes, including learning, memory, and cognition. It is also essential for the normal functioning of the brain and is involved in the pathophysiology of several neurological disorders. Leucine, lysine, and valine are not known to function as neurotransmitters in the CNS.

Schwann cells are a type of glial cell that are found in the peripheral nervous system (PNS). They play a crucial role in supporting and protecting nerve cells by forming the myelin sheath around peripheral nerves. This insulation helps to increase the speed and efficiency of nerve signal transmission. In contrast, the central nervous system (CNS) is composed of the brain and spinal cord, where Schwann cells are not present. Therefore, the correct answer is PNS.

Serotonin is not considered a catecholamine because it is not derived from the amino acid tyrosine, unlike dopamine, norepinephrine, and epinephrine. Catecholamines are a class of neurotransmitters that are synthesized from tyrosine and play important roles in the central nervous system, regulating mood, stress response, and various physiological functions. Serotonin, on the other hand, is derived from the amino acid tryptophan and functions as a neurotransmitter and hormone involved in mood regulation, sleep, appetite, and other processes.

Neuroglia refers to the supporting cells located within the central nervous system (CNS). These cells provide structural support, insulation, and nourishment to neurons. They also play a crucial role in maintaining the homeostasis of the CNS and protecting neurons from damage. Astrocytes, perikaryon, and satellite cells are specific types of neuroglia that perform different functions within the CNS. Therefore, the correct answer is neuroglia.

Prozac is a selective serotonin reuptake inhibitor (SSRI) drug, meaning it blocks the reuptake of serotonin into presynaptic axons. By doing so, Prozac increases the levels of serotonin in the brain, which can help alleviate symptoms of depression, anxiety, and other mood disorders. Valium and Xanax are benzodiazepines used to treat anxiety disorders, while Deprenyl is a medication used to treat Parkinson's disease. Therefore, Prozac is the correct answer in this context.

Huntington's chorea is a neurodegenerative disorder characterized by the progressive loss of motor control. It has been linked to a deficiency in the neurotransmitter gamma-aminobutyric acid (GABA). GABA is an inhibitory neurotransmitter that helps regulate the excitability of neurons in the brain. A deficiency in GABA can lead to an imbalance in brain activity, resulting in the symptoms associated with Huntington's chorea. Therefore, the correct answer is GABA.

Valium, also known as diazepam, is a benzodiazepine medication that acts as a central nervous system depressant. It enhances the inhibitory effects of gamma-aminobutyric acid (GABA), which is a neurotransmitter that inhibits neural transmission in the brain. Therefore, Valium has an effect on GABA to inhibit neural transmission.

Tetrodotoxin is the correct answer because it is a potent neurotoxin that blocks sodium channels. Sodium channels are responsible for the propagation of action potentials in nerves and muscles. By blocking these channels, tetrodotoxin prevents the normal transmission of electrical signals in the body, leading to paralysis and potentially death. Strychnine is a toxin that acts on the central nervous system, Neostigmine is a medication used to treat myasthenia gravis, and Curare is a toxin that blocks nicotinic acetylcholine receptors.

Saltatory conduction refers to the process of nerve impulse propagation along myelinated axons, specifically between the nodes of Ranvier. In this type of conduction, the nerve impulse "jumps" from one node of Ranvier to the next, rather than traveling continuously along the entire length of the axon. This allows for faster and more efficient transmission of the nerve impulse, as the myelin sheath insulates and speeds up the impulse between the nodes.

Endopeptidases are enzymes that break down proteins by cleaving peptide bonds within the protein chain. Clostridium botulinum, a bacterium that causes botulism, releases endopeptidases that specifically target and destroy peptide bonds in proteins. This action leads to the degradation of proteins and contributes to the pathogenicity of the bacterium. Therefore, endopeptidases are the correct answer as they are the enzymes released by Clostridium botulinum that destroy peptide bonds.

Astrocytes are the most common type of cells in the central nervous system (CNS). They are star-shaped cells that provide support and nourishment to neurons, regulate the chemical environment of the brain, and help maintain the blood-brain barrier. Astrocytes also play a role in repairing damaged brain tissue and modulating synaptic activity. Their abundance and diverse functions make them essential for the proper functioning of the CNS.

Ependymal cells are the correct answer because they line the ventricles of the brain and the central canal of the spinal cord. These cells have cilia on their surface that help circulate cerebrospinal fluid and provide a barrier between the fluid and the surrounding nervous tissue. Astrocytes are a type of glial cell that provide support and nourishment to neurons. Schwann cells are found in the peripheral nervous system and are responsible for myelinating axons. Oligodendrocytes are found in the central nervous system and also myelinate axons.

Denoaxonic is not considered a type of synapse. The other options listed, dendrodendritic, axosomatic, and axoaxonic, are all types of synapses that occur between different parts of neurons. However, denoaxonic is not a recognized type of synapse in neuroscience.

Excessive polarization due to GABA is created due to the opening of Cl- channels. GABA (gamma-aminobutyric acid) is an inhibitory neurotransmitter in the central nervous system. When GABA binds to its receptors, it opens Cl- channels, allowing Cl- ions to enter the cell. This influx of negatively charged Cl- ions causes hyperpolarization, making the cell more negative and less likely to fire an action potential. This inhibitory effect helps to regulate and balance neuronal activity in the brain.

Cocaine blocks the re-uptake of monoamines in the nervous system. Monoamines are a class of neurotransmitters that include dopamine, norepinephrine, and serotonin. By blocking their re-uptake, cocaine increases the levels of these neurotransmitters in the synaptic cleft, leading to increased stimulation of the postsynaptic neuron and an overall increase in neurotransmission. This is what contributes to the stimulant effects of cocaine, such as increased energy, euphoria, and heightened alertness.

Calmodulin is a regulatory protein found in the cytoplasm that plays a crucial role in various processes at the synapse. It binds to calcium ions and undergoes conformational changes, which allows it to interact with other proteins and regulate their activity. By binding to and activating or inhibiting target proteins, calmodulin helps to control processes such as neurotransmitter release, synaptic plasticity, and neuronal signaling. Therefore, calmodulin is an essential regulatory protein involved in synaptic function.