Blood physical-chemical peculiarities and constants.

1. Blood colour - depends on haemoglobine. Arterial blood is brightly red because of oxyhaemoglobine (haemoglobine connected with oxygen) big amount. Venous blood is dark red with blue shade. Such blood colour is linked with presence not only of oxydated haemoglobine but also reducted haemoglobine.

2. Blood viscosity or internal friction. It is often determined comparatively to water viscosity: if the latest one is equal to 1, blood viscosity is equal to 4,0-5,0. In new-borned - 10,0-14,0; in 1 month – like in the adult. In girls this index is less than in boys. Main reasons for viscosity increasing:

· in mountains;

· hypercapnia (carbonic acid content increasing in blood);

· inflammations;

· hypertony;

· atherosclerosis;

· at feeding of mainly animal food (proteins-rich) – meat, eggs.

Main reasons for viscosity decreasing:

· at vegeteranian feeding.

Viscosity depends on formed elements (mainly erythrocytes) amount and proteins concentration.

3. Blood density – 1,056-1,060. It is increased at blood condensation; it is decreased – at its liquerfaction. Density level depends on formed elements (mainly erythrocytes) amount and proteins concentration.

4. Osmotic pressure – force that makes water transmit from less concentrated solution in more concentrated. Sodium chloridum is essential for its support (60 per cent of this pressure depends on it). It is the same in all internal environment elements (blood, lymph, tissular liquid). It remains constant even at big water and salts passing into the blood because of their removal by kidneys. Osmotic pressure is supported by means of receptors located in vascular vessels wall and in hypothalamus. Normal value: 7,3-7,6 atmospheres. Solutions with equal osmotic pressure are called isotonic (for example, 0,85% solution of sodium chloridum, 5,5 % solution of glucose). If osmotic pressure in solution is more - it is called hypertonic and, correspondingly, if less - hypotonic.

5. Oncotic pressure - is created by blood proteins (mainly low-weighted albumines). Its level is fluctuated from 25 till 30 mm merc col under physical conditions. It is essential for:

· transcapillary exchange;

· uropoiesis;

· absorbtion;

· lymph formation (lymphopoiesis).

6. Acid-alkaline equillibrium – correlation between acid and alkaline equivalent in blood. This is reaction caused by H⁺-ions concentration. PH or hydrogenium index is used for its evaluation. If pH is equal to 7,0 the environment is called neutral; less than 7,0 – acid; more than 7,0 – alkaline. Norma: in venous blood – 7,34, arterial blood – 7,4; blood in a whole – 7,35-7,47. At birth acidosis is physiologic. Ph is supported by: buffer systems, excretory organs and lungs.

Buffer systems:

· bicarbonate,

· phosphate,

· protein,

· haemoglobine (75 per cent of all system).

At muscular tension increasing acid products come into blood (lactic acid, carbonic acid) and movement to acid side (acidosis) is observed. At increased carbonic acid releasing (with lungs at hyperventillation) movement to alkaline side (alkalosis) occurs.

Blood protheins are 7-8 % or 65-85 g/l. Their population is not homogenic.

Albumins – (60 % or 35-50 g/l) produced in liver; are agile, low-weighted, they are important for:

· oncotic pressure support;

· bilirubin transport;

· hard metals salts transport;

· fat acids transport;

· medicines transport (proteins increase action periods for them).

Globulins (40% or 30-35 g/l) are formed in liver, bone marrow, spleen. Role:

· form antibodies;

· antitoxines;

· agglutinines;

· blood coagulation (some of them are clotting factors);

· phospholipid transport;

· cholesterol transport;

· steroid hormones transport;

· oncotic pressure support (less than albumins);

· blood density support;

· buffers;

· blood viscosity determination;

· nutritive function.

 

Erythrocytes Er (red blood cells RBC)

They were discovered in 17^th century. They vary in their shape:

· discocytes (76 per cent);

· stomatocytes;

· echinocytes;

· spherocytes;

· torocytes;

· dacryocytes;

· planocytes;

· spherocytes;

· ovalocytes;

· acanthocytes and others.

Poikilocytosis - if one can see erythrocytes of different shape in 1 eyesight field simultaneousely. Discoid shape the most widely-spread among RBC allow them transmit capillary better.

Er also differ in their sizes:

· normocytes - cells with diameter 7,5-8,3 mcm and width about 2,1 mcm (their amount is approximately equal to 68 per cent);

· microcytes – if diameter is less (about 15 per cent);

· macrocytes - with larger diameter.

Anizocytosis - if one can see erythrocytes of different size in 1 eyesight field simultaneousely.

Human erythrocytes have no any nucleus. This fact allows them to come through capillary easily. Er is covered by membrane which has antigenic features. This membrane can adsorb and desorb substances coming into blood. Human Er possess large adsorbtive-desorbtive potential. RBC membrane permeability is important for organism availability. Er membrane may be destructed in hypotonic solutions (water, acid et al.) that leads to haemolysis development.

Haemolysis kinds:

1. According to causative agent action:

· mechanic (shaking up, vibration);

· chemical (chlorophorm);

· physical (electrical current);

· osmotic (sodium natrium action);

· biologic (some snakes poisons).

2. According to localization:

· intracellular;

· intravascular (at blood transmissions, toxic animals and insects bites and so on).

Osmotic resistance (ability to resist osmotic forces) is index characterized intravascular haemolysis. Norma: 0,32-0,48% of sodium chloridum.

Er membrane is charged negatively; at this negative charge decreasing RBC can glue together and sedimentate. This reaction received the name velocity sedimentation rate (VSR). Under norma:

· in men – 2,0-10,0 mm/h - widely-spread among doctors (according to new data – 6,0-12,0);

· in women – 2,0-15,0 mm/h (according to new theoretic data - 8,0-15,0) (up to 15,0 - at pregnancy due to hyperfibrinogenemia and at menses as a result of erythrocytes number decreasing because erythrocytes are easily to sedimentate under such conditions);

· in new-borns – 1,0-2,0 mm/h;

· in babies (1 year) – 4,0-10,0 mm/h;

· in the old of both sexes – up to 15,0-20,0 mm/h.

VSR depends on fibrinogen concentration in blood: if its content is more than 3,0 g/l (norma – 2,0-4,0 g/l) VSR is increased. It’s observed in pregnant women and at inflammatory processes. VSR reducing less than 2,0 mm/h – is unfavourable diagnostic sign. But at the same time this index increasing up to 40-100 mm/h (especially to upper limit) may be the sign of tumors particularly malignant.

Erythrocytes amount under norma in men 4,4-5,0 x 10¹²/l; in women – 3,7-4,5 x 10¹²/l. Erythrocytosis means Er amount increasing:

1. Physiological:

· in new-borns;

· at physical work;

· in mountains.

2. Pahological:

· real polycytaemia - Vakez’ disease.

Erythropenia – RBC amount decreasing:

· in pregnant;

· at irradiations et al.

Haemoglobine is an essential structural part in Er. Normal values:

· in men – 135-180 g/l;

· in women – 120-160 g/l;

· in new-borns – up to 200 g/l;

· in pregnant women – up to 110 g/l (physiological hypochromic anaemia).

Main role: oxygen transport (oxyhaemoglobin) and CO₂ (carbohaemoglobine). Adult haemoglobine consists of fractions: “A” – 95-98%, A₂ – 2-3%; fetal haemoglobine (Hb F) – 1-2%.

One can tell about Er saturation by haemoglobine on so-called colour index (CI). It is relative index characterizing Er saturation with Hb. Under norma this index is equal to 0,75-1,0. Er at such CI are called normochromic; if it is more than 1,0 – hyperchromic; less than 0,75 – hypochromic.

Erythrocytes functions:

1. Respiratory – O₂ and CO₂ transport.

2. Metabolic – participation in proteins, fats and carbohydrates, water and salts exchange.

3. Transport - proteins, fats, carbohydrates, medicines.

4. Buffer (haemoglobine buffer).

5. Participation in iron metabolism.

6. Bile-formation regulation.

7. Erythropoiesis.

8. Antitoxic function.

9. Blood coagulation and fibrinolysis.