Filtration plays an integral role in the passive movement solutes in the
A) kidneys
B) stomach
C) small intestines
D) liver
The correct answer and explanation is:
The correct answer is A) kidneys.
Filtration is a vital process that occurs in the kidneys, where it plays an essential role in the passive movement of solutes. The kidneys filter blood to remove waste products and excess substances, such as water, salts, and urea, which are then excreted in urine. This process begins in the glomerulus, a network of tiny blood vessels in the kidney’s nephron. Blood enters the glomerulus under pressure, and as it passes through, the pressure forces water, small solutes, and waste products through the glomerular capillary walls into the Bowman’s capsule. This is the first step of filtration.
The filtration process is passive because it depends on the pressure gradient between the blood in the glomerulus and the filtrate in the Bowman’s capsule. Larger molecules like proteins and blood cells are too large to pass through the filtration membrane and remain in the bloodstream. The filtrate that is collected then moves into the proximal convoluted tubule, where some substances, like glucose and amino acids, are reabsorbed back into the bloodstream, while waste products remain in the filtrate.
This selective filtration helps the kidneys maintain homeostasis by regulating the composition of blood and controlling the body’s fluid balance. The remaining filtrate continues through the nephron, undergoing further processes such as reabsorption and secretion, until it is finally excreted as urine.
While filtration also occurs in other organs like the liver (which filters toxins) and the small intestines (where nutrients are absorbed), it is in the kidneys where filtration is primarily responsible for removing waste and maintaining the balance of solutes in the body.