Blood plasma and blood cells













is the major plasma protein, normal concentration 35 – 53 g / l; about 10 – 12 g albumin are
produced daily. M[r] ≈ 67 000 (585 amino acid residues).

Albumin is essential for the maintaining of oncotic pressure in capillaries.

Because of a negative net electric charge (~ 12 mmol/l), it acts as an

important buffer base and in binding of Ca^2+  (about 50 % of total calcium).

Hydrophobic areas of the surface of albumin molecules provides the

transport of free fatty acids, bilirubin, and also, weakly and non-specifically of steroid and
thyroid hormones, and numerous drugs (e.g., salicylates, penicillins, sulfonamides, and
barbiturates).



Transthyretin (prealbumin)

is a tetrameric protein, M[r] 50 000. Serum concentration 100 - 400 mg/l. Biological function –
binding of thyroxin and retinol-binding protein. Due to its very short biological half-life (2
days) it serves as a marker of malnutrition, impairment or recovery of liver proteosynthesis.



Transferrin

b[1]- Glycoprotein, M[r] ≈ 79 000, serum concentration 2.5 – 4.0 g / l.

It transports Fe^3+ ions. Molecule of transferrin can bind two ferric ions, Under normal
conditions, about 1/3 of the total iron-binding capacity is saturated.

In iron deficiency, the synthesis of transferrin is stimulated.

In chronic alcoholism, glycosylation of transferrin is impaired and detection of
carbohydrate-deficient transferrin (CDT) may serve as a marker of chronic alcohol abuse.



is an a[1]-glycoprotein, normal serum concentration about 2 – 4 g / l.

M[r] ≈ 54 000. This protein inhibits proteinases released from polymorphonuclear leukocytes (namely
elastase) and other proteinases, which may occur in blood plasma  and attack the elastin between
alveoli in the lung.

a[1]-Antitrypsin deficiency is one of the common inborn error. Individuals with the genotype ZZ
produce less than 15 % on usual amounts of [1]AT and they are exposed to a high risk of pulmonary
emphysema due to enzymatic degradation of elastin in the lungs, with consequent reduction of the
surface area available for gas exchange.







If the smaller vessels are injured by traumas, the leakage of blood is discontinued normally in few
minutes due to a series of interactions between the vessel wall, blood platelets, coagulation
factors, and the fibrinolytic system.

The initial step in haemostasis is arteriolar vasoconstriction, which temporarily reduces local
blood flow.

Blood platelets adhere then to the vessel wall at the site of injury, aggregate to each other,
forming so the initial, unstable primary platelet plug ("white thrombus").

Vascular injury also activates coagulation factors that form thrombin, which converts plasma
fibrinogen to insoluble, crosslinked fibrin and relatively resistant - the secondary,
platelet-fibrin plug ("red thrombus").

                 The blood cells are caught in a network of fibrin.

                 Local formation of fibrin activates local generation of

                 plasmin, an enzyme of the fibrinolytic system, which

                 digests fibrin plugs (in parallel with tissue repair

                 processes).



















Biconcave shape, diameter 8 mm, deformations are possible. High surface-to-volume ratio facilitates
gas exchange.

Nonnucleated, no cellular organelles, cytoskeletal components.

Concentration of haemoglobin in RBC is about 330 g / l (~ 95 % of all proteins).

Production of erythrocytes from red cell progenitors is located in the bone marrow and regulated by
erythropoietin synthesized mainly by the kidney.

Reticulocytes still containing ribosomes and elements of ER are released into the circulation where
they transform into adult red blood cells.





are transmembrane single-passing glycoproteins. The saccharidic component (60 % by mass) consists
of numerous oligosaccharides. It is highly sialylated and represents the major part of the
glycocalyx on the outer surface. The negative electric charges prevent agglutination of RBC.

Polymorphism of glycophorin A in its amino acid sequence denotes the MN blood groups of
individuals´ erythrocytes.



Anaerobic glycolysis, producing lactate, is the energy source.

The synthesis of 2,3-bisphosphoglycerate, closely associated to glycolysis,

affects the affinity of haemoglobin for dioxygen.

The pentose phosphate pathway is efficient, it metabolizes  up to 10 % of

the total flux of glucose. NADPH produced is required for the reduction of oxidized glutathione and
methaemoglobin

In the adult RBC, glycogenesis, synthesis of fatty acids, cholesterol, proteins, and nucleic acids
cannot occur, as well as catabolism of fatty acids and ketone bodies.

Some lipids (e.g. phospholipids, cholesterol) from the red cell membrane can exchange with
corresponding lipids of plasma lipoproteins.