26 Year 3: Endocrine and Metabolic Pathology exam questions on Neurochemistry Test – Questions and Answers for medical students. Includes MCQs, answers, explana
This MCQ set contains 26 questions on Neurochemistry Test – Questions and Answers in the Year 3: Endocrine and Metabolic Pathology unit. Each question includes the correct answer and a detailed explanation for active recall and exam preparation.
Correct answer: C – Endorphins
Endorphins are the body's natural opioids that create feelings of euphoria and pain relief. During intense exercise like running, the body releases endorphins, which bind to opioid receptors and produce the characteristic "runner's high" - a feeling of well-being and reduced pain perception. ---
Correct answer: A – GABA
GABA (Gamma-Aminobutyric Acid) is the primary inhibitory neurotransmitter in the brain. Low GABA activity is associated with increased anxiety, as GABA normally helps calm neural activity. Many anti-anxiety medications work by enhancing GABA function. ---
Correct answer: C – In the nucleus
The nucleus contains the cell's DNA, which stores all genetic information. This DNA is transcribed into mRNA, which then travels to ribosomes for protein synthesis. The nucleus is the central control center for all cellular functions. ---
Correct answer: B – GABA and glycine
GABA is the major inhibitory neurotransmitter in the brain, while glycine is the major inhibitory neurotransmitter in the spinal cord. Both cause hyperpolarization of the postsynaptic membrane, making it less likely to fire an action potential. ---
Correct answer: B – The role of sodium channels in depolarization
Tetrodotoxin specifically blocks voltage-gated sodium channels, preventing action potentials from occurring. This demonstrates that sodium influx through these channels is essential for depolarization and action potential generation. ---
Correct answer: C – Serotonin
Serotonin is strongly associated with mood regulation. Low serotonin levels are linked to depression, anxiety, and other mood disorders. SSRIs (Selective Serotonin Reuptake Inhibitors) are commonly prescribed antidepressants that increase serotonin availability. ---
Correct answer: C – Neuron membranes have sodium/potassium ion pumps that take out potassium ions
This statement is incorrect. The sodium-potassium pump actually pumps potassium ions INTO the cell and sodium ions OUT of the cell (3 Na+ out, 2 K+ in). This maintains the concentration gradients necessary for the resting potential. ---
Correct answer: E – Serotonin
Serotonin plays a crucial role in sleep regulation. It's a precursor to melatonin and helps regulate sleep-wake cycles. Imbalances in serotonin can lead to sleep disorders including insomnia. ---
Correct answer: C – Glutamate
Glutamate is the primary excitatory neurotransmitter in the brain. Excessive glutamate activity or insufficient GABA inhibition can lead to seizures, as the brain becomes hyperexcitable with uncontrolled neuronal firing. ---
Correct answer: C – Pleasure
Dopamine is central to the brain's reward system and pleasure pathways. It's released in response to rewarding experiences and motivates behavior toward pleasurable activities. This is why dopamine is often called the "feel-good" neurotransmitter. ---
Correct answer: E – Pleasure
Endorphins are the body's natural opioids that produce feelings of pleasure and well-being. They're released during exercise, stress, pain, and other activities, binding to opioid receptors to create euphoric feelings and reduce pain perception. ---
Correct answer: C – Dopamine
Parkinson's disease is characterized by the death of dopamine-producing neurons in the substantia nigra. This leads to decreased dopamine levels, causing the characteristic motor symptoms like tremors, rigidity, and bradykinesia (slowness of movement). ---
Correct answer: A – Acetylcholine
Alzheimer's disease involves significant loss of acetylcholine-producing neurons, particularly affecting memory and cognitive function. Cholinesterase inhibitors, which increase acetylcholine availability, are used as treatments for Alzheimer's. ---
Correct answer: A – Peptide neurotransmitter precursors and their enzymes are axonally transported in vesicles
Peptide neurotransmitters are synthesized in the cell body and transported down the axon in vesicles, while small-molecule neurotransmitters are typically synthesized locally at nerve terminals. This is a key distinguishing feature between these two types of neurotransmitters. ---
Correct answer: D – Norepinephrine
Most postganglionic sympathetic neurons release norepinephrine (noradrenaline) as their neurotransmitter. This activates adrenergic receptors on target organs, producing the "fight or flight" response characteristic of sympathetic activation. ---
Correct answer: A – They interact with specific opioid receptor proteins to produce their effects
Enkephalins are endogenous opioid peptides that bind to opioid receptors (mu, delta, and kappa) to reduce pain perception. They work similarly to morphine and other opioid drugs by activating these same receptor systems. ---
Correct answer: B – The postsynaptic receptors
The type of postsynaptic receptors determines whether the effect will be excitatory or inhibitory, and the magnitude of the response. The same neurotransmitter can have different effects depending on which receptors are present on the postsynaptic cell. ---
Correct answer: D – During the absolute refractory period
During the absolute refractory period, sodium channels are inactivated and cannot be reopened regardless of stimulus strength. This ensures unidirectional propagation of action potentials and limits firing frequency. ---
Correct answer: B – It would definitely be less negative than the normal resting potential
If sodium channels were normally open, sodium would continuously flow into the cell down its concentration gradient, making the inside less negative (more positive) than the normal resting potential of -65 mV. ---
Correct answer: E – Make use of faster internodal passive electrical conduction
Myelination allows for saltatory conduction, where the action potential "jumps" from node to node via fast passive electrical conduction through the myelinated segments, rather than having to actively propagate along the entire axon length. ---
Correct answer: B – Reduce neurotransmitter release at a synapse
Autoreceptors provide negative feedback control. When activated by the neurotransmitter they respond to, they reduce further neurotransmitter release, serving as a self-regulating mechanism to prevent excessive synaptic activity. ---
Correct answer: A – Exocytosis
Exocytosis is the process by which synaptic vesicles fuse with the presynaptic membrane and release their neurotransmitter contents into the synaptic cleft. This is triggered by calcium influx following action potential arrival. ---
Correct answer: B – Voltage-Dependent (gate
Voltage-gated calcium channels open when the action potential reaches the presynaptic terminal. The influx of calcium ions triggers the fusion of synaptic vesicles with the membrane, leading to neurotransmitter release via exocytosis. ---
Correct answer: D – Packaged in small synaptic vesicles
Small molecule neurotransmitters (like acetylcholine, dopamine, serotonin) are stored in small, clear synaptic vesicles, typically synthesized locally at nerve terminals, unlike peptide neurotransmitters which are made in the cell body. ---
Correct answer: A – Packaged in large synaptic vesicles
Small molecule neurotransmitters are packaged in small synaptic vesicles, not large ones. Large dense-core vesicles are typically used for peptide neurotransmitters and neuromodulators. ---