Final answer:
Secondary hypertension can occur due to a renin-secreting tumor, as renin raises blood pressure by increasing sodium and water retention through aldosterone release.
Step-by-step explanation:
Secondary hypertension may result from a renin secreting tumor. Renin, secreted by the juxtaglomerular complex in the kidneys, acts on angiotensinogen to produce angiotensin I, which is then converted into angiotensin II by the angiotensin-converting enzyme (ACE). Angiotensin II is a potent vasoconstrictor that increases blood pressure and stimulates the release of aldosterone from the adrenal cortex. Aldosterone promotes sodium and water retention by the kidneys, thereby increasing blood volume and blood pressure.
Conversely, tumors that secrete the atrial natriuretic factor would help to lower blood pressure by promoting the loss of sodium and water. Aldosterone antagonists and epinephrine antagonists would generally lower blood pressure rather than cause secondary hypertension.