Anatomy and Physiology II Practice Test

The correct choice is based on the process that occurs in the kidneys during urine formation, specifically in the nephron. Filtration is the mechanism that forces water and solutes from the blood in the glomerulus into Bowmann's capsule, which is part of the nephron. This occurs primarily due to the hydrostatic pressure exerted by the blood within the capillaries of the glomerulus. The high blood pressure in the glomerulus is essential for pushing fluid into the Bowmann's capsule, allowing the kidneys to begin the process of urine formation by separating waste products and excess substances from the bloodstream.

Other processes mentioned, such as reabsorption, secretion, and excretion, relate to other phases of kidney function. Reabsorption involves the movement of water and solutes back into the blood after filtration has occurred, while secretion pertains to the active transport of substances from the blood into the nephron tubule, further modifying the filtrate. Excretion refers to the process of eliminating waste products from the body, which follows the formation of urine. Therefore, filtration is the precise term for the initial movement of substances into Bowmann’s capsule due to blood pressure.