Blood volume

Blood volume refers to the total amount of circulating fluid within the vascular system at any given time. It consists primarily of plasma and cellular elements such as red cells. Blood volume is tightly regulated through neural mechanisms (autonomic nervous system), hormonal pathways—most notably the renin–angiotensin–aldosterone system and antidiuretic hormone—and renal excretion/reabsorption processes that control both water and electrolyte balance. The kidneys play a central role in adjusting plasma composition via glomerular filtration rate changes, sodium reabsorption/excretion, and erythropoietin-mediated regulation of red cell mass ("critmeter" function). Blood pressure sensors such as baroreceptors provide feedback on effective circulating blood flow rather than direct measurement; thus most regulatory systems respond to changes in perfusion rather than absolute intravascular fluid content. Disruptions in these regulatory systems can lead to clinical conditions including hypovolemia/shock or hypervolemic states like edema.

Other names

Circulating blood volumeIntravascular volumePlasma volumeWhole blood volume

Not applicable for "blood volume" as it is not a drug target. Mechanisms relate to modulation of renal handling of sodium/water or hormonal regulation: - Inhibition/stimulation of renal tubular transporters for Na+/water - Modulation of RAAS pathway components - Antidiuretic hormone action on kidney collecting ducts