Question

Complete the following paragraph by selecting the option that correctly fills the blanks (i) – (iv).
The kidneys have built-in mechanisms for the regulation of glomerular filtration rate. One such efficient mechanism is carried out by (i). It is a special sensitive region formed by cellular modifications in the (ii) and the (iii) at the location of their contact. A fall in GFR can activate the JG cells to release (iv) which can stimulate glomerular blood flow and thereby bring GFR back to normal.
A. ANF PCT Efferent arteriole Angiotensin
B. ANF DCT Afferent arteriole Renin
C. JGA PCT Efferent arteriole Angiotensinogen
D. JGA DCT Afferent arteriole Renin

Answer 1

In vertebrates, the kidneys are a pair of reddish-brown bean-shaped organs. In the retroperitoneal space, they can be found on the left and right. The paired renal arteries supply blood, and the paired renal veins return blood. A ureter is a tube that connects each kidney to the bladder and transports discharged urine. The kidneys perform a number of important regulatory tasks.

Complete answer :
D. JGA DCT Afferent arteriole Renin : The glomerular filtration rate is regulated by mechanisms built into the kidneys. JGA is one such effective method. It's a sensitive zone created by cellular changes in the DCT and the Afferent arteriole at their meeting point. When GFR drops, JG cells release renin, which stimulates glomerular blood flow and restores GFR to normal.
The juxtaglomerular apparatus or JGA (also known as the juxtaglomerular complex) is a kidney structure that controls the function of each nephron, or functional unit of the kidney. Because it is located close to the glomerulus, it is called the juxtaglomerular apparatus.
A section of the kidney nephron between the loop of Henle and the collecting tubule is known as the distal convoluted tubule (DCT).
In many excretory systems, the afferent arterioles are a collection of blood arteries that supply the nephrons. As part of the tubuloglomerular feedback mechanism, they play a vital role in blood pressure regulation.
Renin, also known as angiotensinogenase, is an aspartic protease protein and enzyme released by the kidneys that regulates extracellular fluid volume and arterial constriction through the renin–angiotensin–aldosterone system, sometimes known as the renin–angiotensin–aldosterone axis. As a result, it helps to maintain the body’s mean arterial blood pressure.

Additional information :
ANF PCT Efferent arteriole Angiotensin : The amino acid polypeptide hormone atrial natriuretic factor (ANF) is released primarily by the heart atria in response to atrial strain. By exchanging hydrogen ions in the interstitium for bicarbonate ions in the filtrate, the proximal convoluted tubule (PCT) effectively regulates the pH of the filtrate. Hence option A is not correct.
ANF DCT Afferent arteriole Renin : All other options except ANF or Atrial Natriuretic Factor are correct. Since ANF is wrong, option B is not correct.
JGA PCT Efferent arteriole Angiotensinogen : Options PCT, efferent arteriole and Angiotensinogen are wrong. Hence option C is not correct.

So, the correct answer is option D. JGA DCT Afferent arteriole Renin.

Note :
The kidneys perform a number of important regulatory tasks. Electrolyte regulation, acid-base balance maintenance, and blood pressure regulation are all dependent on them. They help the body by filtering blood and removing wastes that would otherwise be excreted in the urine bladder. The kidneys are responsible for excreting wastes such as urea and ammonium, as well as the reabsorption of water, glucose, and amino acids.