Inorganic constituents of blood plasma. Water-mineral metabolism. Acidosis and alkalosis

Inorganic compounds carry out the next functions:

1) structural (phosphorus, calcium, fluorine)

2) regulatory (for pH – sodium, chlorine and pottassium; for osmotic pressure – sodium and chlorine)

3) they act as coenzymes and activators of some hormones(iodine for thyroid gland; iron for hemoglobin, myoglobin, catalase, peroxidase, cytochromes)

4) specific action (in different biologic processes)

Macroelements are measured by 10^-3% and more (in gram): sodium, pottassium, calcium, magnesium, iron, phosphorus, fluorine, chlorine, sulfur.

Microelements are measured by 10^-3% and less: iodine, selenium, zinc, copper, manganese, cobalt

Sodium: sources, depot, biologic role, level in blood plasma, concept of hyper- and hyposodiumemia

NaCl is a main source of sodium. Sodium is stored as Sodium chloride in skin.

Biologic role: 1) regulatory (pH, osmotic pressure); 2) nervous-muscular excitability; 3) takes part in absorption of amino acids and glucose; 4) is a component of Na-K-ATP-ase.

Na-K-ATP-ase is enzyme of membranes which catalyzes the cleavage of ATP for transport through membranes. Pottassium may cross the membrane from cells into extracellular matrix passively. Such way is characteristically for sodium but vice versa (from extracellular matrix into cells). This occurs in polarization of membranes. Restoration of charge of membranes after polarization (repolarization) occurs under action of Na-K-ATP-ase which carries out active transport of sodium and pottassium through membranes (sodium from cells into extracellular matrix and pottassium fron extracellular matrix into cells).

The level of sodium in blood plasma makes up 135-145mM/L. Increase of sodium in blood plasma is observed in chronic renal falure and hyperaldosteronism. Decrease of sodium is observed in serum deprivation and hypoaldosteronism.

Potassium:sources, depot, biologic role, level in blood plasma, concept of hyper- and hyposodiumemia

This element mainly occurs in dry-fruits. It is stored in skin and muscles as KCl.

Biologic role: 1) regulatory (pH); 2) takes part in nervous-musculary excitability with sodium; 3) muscular contraction

The normal level is 3.4-5.0mM/L. Increase of pottassium is observed in trauma, after operations, in hemolysis, burns, hypoaldosteronism. This is dangerous due to sudden stop of heart action. Decrease of pottassium in blood plasma is observed in hyperaldosteronism, application of diuretics. This results in myodystrophy

Sodium and pottassium take part in regulation of pH of blood. This function is due to the formation of buffers’ systems. There are next buffers’ systems in blood plasma: 1) hydrocarbonate’s (H2CO3/NaHCO3); 2) phosphate’s (NaH2PO4/Na2HPO4); 3) protein’s (HPr/NaPr). Buffers’ systems occur in erythrocytes too: 1) hydrocarbonate’s (H2CO3/KHCO3); 2) phosphate’s (KH2PO4/K2HPO4); 3) hemoglobin’s (HHb/KHb, HHBO2/KHbO2)

Acidosis is a phenomenon of increase of acidic products (CO2, H⁺ ) and decrease of basic products (OH^- ). Buffers’ systems take part in regulation of pH. For example, hydrocarbonate’s buffer system:

H2CO3/NaHCO3 + [H⁺] à NaHCO3 + [H⁺] à Na⁺ + H2CO3 (H2O+CO2).

Acidosis may be respiratory (in pneumonia because lack of oxygen and excess of CO2 is observed) and metabolic (e.g. ketoacidosis in diabetes mellitus, lactate acidosis in hypoxia).

Alkalosis is a phenomenon of increase of bases (OH^-) and decrease of acidic products (CO2 and protons).

H2CO3/NaHCO3 + [OH^-] à H2CO3 + [OH^-] à H2O + HCO3^-(anions of bicarbonates are excreted through the kidneys with urine).

Alkalosis may be respiratory (decrease of CO2 in hyperventilation) and metabolic (increase of formation and intake of alkalies).

In details see this topic (Acidosis and alkalosis) in pathologic physiology and textbook of biochemistry and also table below).

<== попередня сторінка	\|	наступна сторінка ==>
Blood clotting system	\|	Acidosis and alkalosis

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