Question

Human urine is usually acidic because
A. Hydrogen ions are actively secreted into the filtrate
B. The sodium transporter exchanges one hydrogen ion for each sodium ion in peritubular capillaries
C. Excreted plasma proteins are acidic
D. Potassium and sodium exchange generated acidity

Answer 1

Hint: A normal adult human excretes, 1 to 1.5 liters of urine per day. The urine excreted is a light yellow colored watery fluid. It is slightly acidic (pH-6.0). The pH is maintained by tubular secretions. It also maintains the pH and ionic balance of body fluids in which hydrogen ions are actively secreted into the filtrate. Bicarbonate ions are reabsorbed.

Complete answer:
Filtration is the process of transfer of soluble components (water and waste) from the blood into the glomerulus.
Reabsorption is the process of absorption of molecules, ions, and water. These are necessary for the body to maintain homeostasis from the glomerular filtrate back into the blood.
Secretion is the process of transfer of hydrogen ions, creatinine, drugs, and urea from the blood into the collecting duct. They are primarily made of water.
In normal conditions, Blood and glucose are not found in urine.
The proximal tubule is the fraction of the nephron of the kidney. It leads from the Bowman's capsule to the loop of Henle. The pH of the filtrate is regulated by exchanging hydrogen ions in the filtrate. The human urine is usually acidic due to the H+ ions as H+ is actively secreted into the filtrate.

So, the correct answer is option A- 'Hydrogen ions are actively secreted into the filtrate'.

Note: Urine is a liquid by-product of metabolism in humans and other animals. Urine gushes from the kidneys through the ureters to the urinary bladder. Urine is excreted from the body through the urethra as a result of Urination.