Which of the following organs filters excess solutes from the blood?
A.
Stomach
B.
Spleen
C.
Kidney
D.
Gallbladder
The Correct answer and Explanation is:
The correct answer is C. Kidney.
The kidneys are vital organs responsible for filtering excess solutes, waste products, and excess fluids from the blood, which is essential for maintaining homeostasis in the body. Each kidney contains approximately one million functional units called nephrons. The nephron is the site of filtration, reabsorption, and secretion, playing a critical role in urine formation.
The filtration process begins in the glomerulus, a network of tiny blood vessels within the nephron. Blood enters the glomerulus through the afferent arteriole, where high pressure forces water, ions, and small molecules, such as glucose and urea, through the glomerular membrane into the Bowman’s capsule. Larger molecules like proteins and blood cells are typically retained in the bloodstream due to their size.
After initial filtration, the filtrate (now called tubular fluid) moves through various parts of the nephron: the proximal convoluted tubule, the loop of Henle, and the distal convoluted tubule. During this journey, the kidneys reabsorb essential substances back into the bloodstream, such as glucose, amino acids, and specific ions, while secreting waste products and excess ions into the tubular fluid. This selective process helps regulate blood pressure, electrolyte balance, and acid-base homeostasis.
Finally, the modified filtrate, now urine, collects in the renal pelvis before being transported to the bladder for excretion. The kidneys also play a role in regulating red blood cell production through the release of erythropoietin and in maintaining blood pressure via the renin-angiotensin-aldosterone system.
In contrast, the stomach is involved in digestion, the spleen filters blood and manages immune responses, and the gallbladder stores bile for fat digestion, none of which are primarily focused on filtering solutes from the blood like the kidneys do. Therefore, the kidneys are uniquely suited to the task of filtering excess solutes and maintaining overall fluid and electrolyte balance in the body.