Final answer:
Renal artery stenosis leads to decreased kidney perfusion, causing the juxtaglomerular apparatus to trigger the renin-angiotensin-aldosterone system, resulting in diastolic hypertension. An angiogram is the diagnostic tool for this condition. This action, mediated by the hormone angiotensin II, helps maintain blood pressure.
Step-by-step explanation:
The condition referred to in the question is renal artery stenosis, which causes a decrease in blood flow to the kidneys, specifically affecting the juxtaglomerular apparatus. This results in a reduced perfusion that triggers the activation of the renin-angiotensin-aldosterone system. Consequently, there's an increase in renin secretion, which leads to the production of angiotensin II, a potent vasoconstrictor that increases blood pressure. Signs and symptoms include diastolic hypertension, and the diagnosis is typically confirmed through an angiogram.
When blood pressure is low, the juxtaglomerular cells release renin, which converts angiotensinogen to angiotensin I followed by conversion to angiotensin II through the action of angiotensin-converting enzyme (ACE) primarily in the lungs. Angiotensin II causes vasoconstriction and stimulates aldosterone production, which leads to an increase in blood volume by retaining sodium (Na+) and water. This complex mechanism helps to restore and maintain blood pressure in the event of decreased renal perfusion.