Effective arterial blood volume (EABV) refers to the adequacy of the arterial blood volume to "fill" the capacity of the
arterial vasculature. Normal EABV exists when the ratio of cardiac output to peripheral resistance maintains venous return and cardiac output at normal levels. EABV can be reduced, therefore, by factors which reduce actual arterial blood volume (hemorrhage, dehydration), increase arterial vascular capacitance (cirrhosis, sepsis) or reduce cardiac output (congestive heart failure). EABV can be reduced in the setting of low, normal, or high actual blood volume. Whenever EABV falls, the kidney is triggered to retain sodium and water.
Maintenance of EABV
In cases of
edema
Edema, also spelled oedema, and also known as fluid retention, dropsy, hydropsy and swelling, is the build-up of fluid in the body's Tissue (biology), tissue. Most commonly, the legs or arms are affected. Symptoms may include skin which feels t ...
, increases in
extracellular fluid
In cell biology, extracellular fluid (ECF) denotes all body fluid outside the cells of any multicellular organism. Total body water in healthy adults is about 60% (range 45 to 75%) of total body weight; women and the obese typically have a lower ...
(ECF) is associated with a corresponding decrease in EABV. The kidneys detect changes in EABV and through Na
+ excretions, they attempt to restore EABV balance. The kidney mechanisms used to restore EABV include, (1) increased
sympathetic nerve activity; (2) decreased
Atriopeptin
Atrial natriuretic peptide (ANP) or atrial natriuretic factor (ANF) is a natriuretic peptide hormone secreted from the cardiac atria that in humans is encoded by the NPPA gene. Natriuretic peptides (ANP, BNP, and CNP) are a family of hormone/pa ...
(ANP) secretion from the atria; (3) increased
oncotic pressure
Oncotic pressure, or colloid osmotic-pressure, is a form of osmotic pressure induced by the proteins, notably albumin, in a blood vessel's plasma (blood/liquid) that causes a pull on fluid back into the capillary. Participating colloids displace ...
(
Starling forces
The Starling equation describes the net flow of fluid across a semipermeable membrane. It is named after Ernest Starling. It describes the balance between capillary pressure, interstitial pressure, and osmotic pressure. The classic Starling equa ...
); (4) increased activity of the
Renin–angiotensin–aldosterone system.
[Costanzo, Linda S. Physiology. 2017. 6th Ed. p. 288]
See also
*
Extracellular fluid
In cell biology, extracellular fluid (ECF) denotes all body fluid outside the cells of any multicellular organism. Total body water in healthy adults is about 60% (range 45 to 75%) of total body weight; women and the obese typically have a lower ...
*
Veins
Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated b ...
References
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Hematology