Final answer:
During sympathetic dominance of RAAS, sympathetic nervous activity increases, causing vasoconstriction of the afferent arterioles and stimulation of the adrenal medulla.
Step-by-step explanation:
During sympathetic dominance of the Renin-Angiotensin-Aldosterone System (RAAS), sympathetic nervous activity increases, resulting in vasoconstriction of the afferent arterioles and stimulation of the adrenal medulla. This leads to decreased blood flow through the kidneys and increased production of angiotensin II and aldosterone, which raise blood volume and pressure. This causes a decrease in blood flow through the kidneys, redirecting blood to other organs with more immediate needs. Additionally, sympathetic nerves stimulate the release of renin, which increases the production of angiotensin II and aldosterone. Angiotensin II stimulates vasoconstriction, while aldosterone promotes sodium and water retention, ultimately increasing blood volume and blood pressure.