Blood - Tissue Functioning and Remodeling in the Circulatory and Ventilatory Systems - page 7

Tabl e 1. 5. Plasma protein composition (%).

Albumin ∼ 0.60

α 1-Globulin ∼ 0.04

α 2-Globulin ∼ 0.08

β -Globulin ∼ 0.12

γ -Globulin ∼ 0.16

Fibrinogen ∼ 0.03

1 g/l) is the blood glucose concentration, which depends on the
exogenous supply and degradation of hepatic glycogen. 6 Glycemia is stabilized by
2 pancreatic hormones, insulin and glucagon. Insulin decreases glucose level by cell
use and storage, especially in the liver and the muscles. Glucagon increases glucose
concentration. When glycemia falls below 70 mg/dl, parasympathetic nerves are
stimulated and hormones are released (adrenaline, cortisol, glucagon, and growth
hormone) to limit glucose uptake. On the other hand, hyperinsulinemia occurs to
compensate for insulin resistance.

Glycemia ( ∼

1.3.3 Plasma Proteins

Serum is plasma without fibrinogen (195-365 mg/dl) and other clotting factors.
Fibrinogen acts on erythrocyte aggregation, 7 hence influencing blood rheology
(Vol. 7), and blood coagulation (Sect. 9.8 ). Main non-protein nitrogens (NPN) are
urea, uric acid, creatine, creatinine, ammonium salts, and amino acids.
Serum proteins are composed of albumin and globulins (Table 1.5 ). Plasma
proteins are responsible for osmotic pressure that maintains fluid balance across
capillaries ( 25 mmHg]; Vol. 6 - Chap. 4. Cardiovascular Physiology).

Albumin is the main plasma protein (3.0-4.5 g/dl; plasma half-life 15-19 days;

∼ 3.3 kPa [ ∼

∼ 60% of total protein) synthesized by hepatocytes. Newly synthesized albumin

is secreted into the circulation at the rate of about 15 g/d in humans. It binds many
small molecules for transport in the blood and participates in blood colloidal osmotic
pressure ( ), which keeps fluids within the vasculature. Plasma albumin indeed

yields about 65% of osmotic pressure, whereas globulins and fibrinogen contribute
according to their plasma concentrations. Molecular structure and charge of albumin

Π

6 The best measurement technique of glycemia targets the percentage of glycated hemoglobins
(hemoglobin A1c) that reflects the blood sugar levels over the course of a few months. In healthy
individuals, less than 6% of hemoglobin is bound to glucose.
7 Fibrinogen bridges erythrocytes to form rouleaux. Erythrocyte aggregation depends on the
concentration of fibrinogen and β -globulins. The fractal dimension of 2D finite RBC aggregates is
equal to 1

. ± .

03 [ 2 ], which is similar to the result (1.55) of a chemically limited aggregation
model [ 3 ], which gives in 3D a fractal dimension of 3.

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