Which anatomical structure is primarily responsible for filtering blood in the kidneys?

• A. Nephron
• B. Glomerulus
• C. Tubule
• D. Medulla

Answer: (A)

The nephron is the functional unit of the kidney responsible for filtering blood. Each kidney contains about a million nephrons, and they play a crucial role in the regulation of water, electrolytes, and waste products in the body. Within each nephron, the initial process of filtration occurs in a structure known as the glomerulus, which is a network of capillaries that allows for the selective filtration of blood plasma into the Bowman’s capsule.

The nephron then continues with the tubule, where further processing of the filtrate takes place, involving reabsorption and secretion of various substances. The medulla is a region of the kidney that is involved in concentrating urine but does not filter blood directly. Therefore, while all components of the nephron work together for kidney function, the nephron is recognized as the primary structure in the context of blood filtration in the kidneys.