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NEET Questions / Zoology / Chemical Coordination and Integration
A mutation in the gene encoding for 11Ξ²-hydroxysteroid dehydrogenase type 2 (11Ξ²-HSD2) results in apparent mineralocorticoid excess (AME). This is because:
Aldosterone production is increased.
Cortisol is not converted to cortisone in the kidney, allowing it to bind to mineralocorticoid receptors.
The kidneys become insensitive to aldosterone.
Sodium reabsorption in the kidneys is inhibited.
A patient presents with persistent hyperglycemia, muscle weakness, and central obesity. Upon examination, they are found to have elevated cortisol levels. Which of the following is the LEAST likely cause of these symptoms?
Pituitary adenoma secreting ACTH
Adrenal cortex tumor secreting cortisol
Exogenous administration of glucocorticoids
Adrenal medulla tumor secreting epinephrine
Conn's syndrome, characterized by primary hyperaldosteronism, results in specific electrolyte imbalances. Which of the following electrolyte profiles is MOST consistent with this condition?
Hyperkalemia, hyponatremia, and metabolic acidosis
Hypokalemia, hypernatremia, and metabolic alkalosis
Hyperkalemia, hypernatremia, and metabolic alkalosis
Hypokalemia, hyponatremia, and metabolic acidosis
A patient presents with disrupted sleep-wake cycles, depressed mood, and abnormal thermoregulation. Damage to which specific region of the epithalamus is MOST likely responsible for these symptoms?
Habenular nuclei
Pineal gland parenchyma
Posterior commissure
Stria medullaris
A researcher observes increased melatonin secretion in a subject exposed to prolonged darkness. This response is PRIMARILY mediated by which neural pathway?
Optic nerve β Lateral geniculate nucleus β Visual cortex β Pineal gland
Retinohypothalamic tract β Suprachiasmatic nucleus β Superior cervical ganglion β Pineal gland
Vestibulocochlear nerve β Brainstem β Cerebellum β Pineal gland
Olfactory nerve β Olfactory bulb β Amygdala β Pineal gland
Calcified pineal glands are often observed in older individuals. While generally asymptomatic, significant calcification could theoretically interfere with which cellular process MOST crucial for melatonin synthesis?
Pinealocyte cell division
Enzyme activity related to serotonin conversion
Calcium ion transport across cell membranes
Synthesis of tryptophan
A patient presents with recurrent infections, severely depleted T-cell counts, and underdeveloped secondary lymphoid organs. Genetic analysis reveals a mutation affecting a specific receptor crucial for thymocyte development. Which receptor is MOST likely mutated, leading to this severe immunodeficiency?
a) IL-7 receptor
b) CXCR4 receptor
c) Notch1 receptor
d) CCR7 receptor
Hassall's corpuscles, unique structures found within the thymic medulla, are hypothesized to play a role in which of the following processes?
a) Positive selection of thymocytes
b) Production of thymic hormones like thymopoietin
c) Maturation and differentiation of regulatory T cells (Tregs)
d) Removal of apoptotic thymocytes by macrophages
A patient with long-term glucocorticoid therapy is abruptly taken off the medication. Which of the following is the MOST likely immediate consequence related to the adrenal gland?
Acute adrenal insufficiency
Cushing's syndrome
Conn's syndrome
Adrenal hyperplasia
A patient presents with persistent hypokalemia, metabolic alkalosis, and hypertension. Plasma renin activity is suppressed. Which adrenal tumor is the MOST likely cause?
Cortisol-producing adenoma
Aldosterone-producing adenoma
Adrenal medullary tumor (pheochromocytoma)
Adrenocortical carcinoma
