Discuss the concept of "effective circulating volume" in the context of normal pregnancy and consider how blood volume is perceived by the renin angiotensin aldosterone and the nitric oxide system.
a. The concept of effective circulating volume in normal pregnancy
b. How blood volume is perceived by the renin angiotensin aldosterone system in normal pregnancy
c. How blood volume is perceived by the nitric oxide system in normal pregnancy
d. All of the above
