Final answer:
The part of the genitourinary system that regulates blood pressure is renin, an enzyme secreted by the kidneys and involved in the renin-angiotensin-aldosterone system, which controls blood pressure by regulating sodium and water balance. The correct option is b.
Step-by-step explanation:
The part of the genitourinary system that regulates blood pressure is renin. Renin is an enzyme secreted by the kidneys and plays a vital role in the renin-angiotensin-aldosterone system (RAAS), which helps control blood pressure by regulating sodium and water balance.
The RAAS system affects the concentration of sodium in the blood—a key determinant of blood pressure.
Although structures like the ureter, bladder sphincters, and the heart are components of the genitourinary and circulatory systems, it is the release of renin by the kidneys that directly participates in the regulation of blood pressure.
When blood volume or sodium levels are low, or when blood potassium levels are high, the kidneys release renin into the bloodstream. This initiates a series of reactions that lead to the conservation of sodium and water, which in turn raises blood pressure.
Also, the kidneys produce the hormone erythropoietin (EPO), which stimulates red blood cell development and is involved in the oxygen transport capacity of blood, another factor influencing blood pressure. The correct option is b.