Iodine deficiency primarily affects the function of which gland?
A. Adrenal
B. Pituitary
C. Thyroid
D. Pancreas
Answer: Option C
Solution (By JKExamLibrary)
Iodine is essential for the synthesis of thyroid hormones T₃ and T₄. Deficiency causes hypothyroidism and goiter (enlarged thyroid gland). Iodized salt is a preventive measure.
Explanation:
Adenylyl cyclase converts ATP to cyclic AMP (cAMP), a second messenger. Phosphodiesterase breaks down cAMP, PKA is activated by cAMP, PLC produces IP₃ and DAG.
Explanation:
The juxtaglomerular apparatus (JGA) is a specialized structure where the distal convoluted tubule (DCT) comes into contact with the afferent arteriole. It consists of juxtaglomerular cells (modified smooth muscle cells in the afferent arteriole that secrete renin), macula densa cells (modified DCT cells that sense NaCl concentration), and extraglomerular mesangial cells. It plays a crucial role in regulating blood pressure and glomerular filtration rate via the renin-angiotensin-aldosterone system.
Explanation:
Vitamin B₁₂ (cobalamin) contains a cobalt ion at the center of its corrin ring. It is the only vitamin that contains a metal. Iron is in heme, zinc in enzymes, magnesium in chlorophyll.
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