Question

Which of the following is a powerful vasoconstrictor that increases the glomerular blood pressure and there the GFR?
A. Renin
B. Angiotensin-II
C. Aldosterone
D. ANF

Answer 1

Hint: Vasoconstrictor is used to construct the blood carrying tube to increase blood pressure.

Step by step answer:Osmoreceptors in the body are activated by change in blood volume or body fluid volume and ionic concentration.
Falling glomerular blood flow or glomerular blood pressure / GFR can activate the JG cells to release renin which converts angiotensinogen in the blood to angiotensin I and further to angiotensin II.
Angiotensin II being a powerful vasoconstrictor increases the glomerular blood pressure and thereby glomerular filtration rate. Angiotensin II also activates the adrenal cortex to release aldosterone. Aldosterone causes reabsorption of NA+ and water from the distal part of the tubule. This also leads to an increase in blood pressure in the glomerular filtration rate. This complex mechanism is generally known as the renin-angiotensin mechanism.
Hence, the correct answer is ( B ).
Some additional information:
ANF is known as an atrial natriuretic factor. It is also known as an atrial natriuretic peptide. The main function of the atrial natriuretic factor is causing a reduction in expended extracellular fluid volume by increasing renal sodium excretion. The atrial natriuretic factor is synthesized and secreted by cardiac muscle cells in the walls of the atria in the heart. These cells contain volume receptors that respond to increased stretching of the atrial wall due to an increase in arterial blood volume.

Note: Atrial natriuretic factor is only responsible for decreasing blood pressure. The main function of the atrial natriuretic factor is causing a reduction in expended extracellular fluid volume by increasing renal sodium excretion.