Test: Concentration of Filtrate, Regulation of Kidney Function & Micturition - NEET MCQ

Juxtaglomerular cells in the renal cortex synthesize the hormone called Renin. Here's the detailed explanation:

- Renin plays a crucial role in regulating blood pressure and electrolyte balance.
- It is released in response to low blood pressure, low sodium levels, or sympathetic nervous system stimulation.
- Renin acts on angiotensinogen to produce angiotensin I, which is then converted to angiotensin II, a potent vasoconstrictor.
- Angiotensin II helps in increasing blood pressure by constricting blood vessels and stimulating the release of aldosterone to retain sodium and water.

This hormone cascade is essential for maintaining blood pressure and electrolyte balance in the body.

ADH acts in the kidney to regulate the volume and osmolarity of the urine. Specifically, it acts in the distal convoluted tubule (DCT) and collecting ducts (CT) cells. Hence, Option A is the correct option. 

The process described where the urinary bladder contracts and the urethral sphincter relaxes to release urine is known as micturition. This process is controlled by neural mechanisms known as the micturition reflex, initiated by signals sent from stretch receptors in the bladder to the central nervous system. Micturition is essential for the elimination of urine from the body and is a coordinated response involving the bladder muscles and the urethral sphincter.

The presence of glucose (Glycosuria) and ketone bodies (Ketonuria) in urine are indicative of diabetes mellitus. Glycosuria occurs when the blood sugar levels are high, leading to the excretion of glucose in the urine. Ketonuria, on the other hand, occurs when the body breaks down fat for energy instead of glucose, leading to the presence of ketone bodies in the urine. Monitoring these substances in urine can help in diagnosing and managing diabetes mellitus, a metabolic disorder characterized by high blood sugar levels.

Both the assertion and reason are true:

• Urine is indeed prevented from flowing back into the ureters.
• Urethral sphincters do relax during micturition.

However, the reason given does not explain why urine is prevented from flowing back into the ureters. The backflow prevention is due to the vesicoureteral junction, not the relaxation of the urethral sphincters. Therefore, the correct answer is (b).