Question

Which of the following is not true about Juxtaglomerular apparatus ?

• A. Lies at the junction of distal tubule and against the afferent (efferent) arteriole
• B. Arteriole walls have juxtaglomerular cells, enlarged smooth muscle cells, Have secretory granules containing renin, Act as mechanoreceptors
• C. Macula densa function as chemoreceptors (sense concentrations of $(N{a}^{+},K^{+}andC{l}^{-})$ and on sensing higher levels of these ions, release prostaglandins which suppress the granular cells from releasing renin.
• D. Mesangial cells, Have phagocytic and contractile properties, Influence capillary filtration

Answer 1

The correct option is C Macula densa function as chemoreceptors (sense concentrations of $(N{a}^{+},K^{+}andC{l}^{-})$ and on sensing higher levels of these ions, release prostaglandins which suppress the granular cells from releasing renin.

The macula densa cells, sense lower levels of sodium chloride, and release certain prostaglandins, that are local hormones- i.e., signaling molecules like hormones, but which act locally. The prostaglandins trigger the granular cells to release renin and not suppress them.