Physical characteristics of the blood: There is approximately 5-6 liters of circulating blood volume in the cardiovascular system. Water constitutes around 55% of the blood volume in the form of plasma. The normal temperature of blood inside the human body is 38°C (100.4°F). Normal pH is 7.35 – 7.45.
Within the plasma are proteins which serve special functions. Albumin (54% of the plasma proteins) provides the osmotic gradient which draws water from the interstitial space around the capillaries back into the vascular space on the venous side of the capillaries. Albumin also serves as a reservoir for medications and other substances in the blood. Therefore, when a patient’s albumin level is low (hypoalbuminemia), two things might result: the patient may develop edema from “third spacing” of water into the interstitial space; another consequence may be that a patient’s serum drug level may become elevated if the drug is bound to plasma proteins.