How do changes in sympathetic and parasympathetic activity influence heart rate

Could you elaborate on the physiological mechanisms underlying the regulation of blood pressure in the human body, including the roles of the autonomic nervous system, baroreceptor reflex, and renal function? How do changes in sympathetic and parasympathetic activity influence heart rate, stroke volume, and peripheral vascular resistance to maintain blood pressure within a normal range? Additionally, how does the renin-angiotensin-aldosterone system respond to alterations in blood volume and sodium levels, ultimately affecting blood pressure regulation through vasoconstriction and fluid retention?