Test Questions

1. What is the mineral composition of blood?

2. Give the equations describing the mechanism of action of the main blood buffer systems.

3. When do hypocalcemia and hypercalcemia develop?

4. What is the difference between serum and plasma?

5. Specify causes of hypo-and hyperproteinemia.

Laboratory work 9. Detection of bile pigments in urine

Bilirubin in normal urine cannot be open by the usual methods, although it may be in it in trace amounts. Excretion of bilirubin in the urine is increased with hyperbilirubinemia. In these cases, qualitative tests for bilirubin become positive. Reactions for the bile pigments are based on the formation of colored products of bilirubin oxidation: biliverdin (green), bilitsianin (blue), holetelin (yellow), etc.

In the test tube put 1 ml of concentrated nitric acid and gently layer urine from pipette. The reaction is called "Gmelin’s test". It is based on the oxidation of urine bilirubin under the influence of nitric acid with a mixture of nitrous acid in a number of differently colored oxidation products. In the presence of bile pigments in the boundary of two fluids green, blue, purple, red and yellow rings appear in the sequence that corresponds to different degrees of oxidation of bilirubin. Furthest from the nitric acid is a green ring of biliverdin (least oxidized product), the closest to the nitric acid is a yellow ring of holetelin (the most oxidized product).

Test Questions

1. Give a scheme for the formation of bilirubin in the body.

2. What is a "direct" and "indirect" bilirubin?

3. What types of jaundice cause hyperbilirubinuriya?

4. How to distinguish obstructive jaundice from hemolytic jaundice using the blood test?

Laboratory work 10. Biochemistry of bone and connective tissue

Bone tissue contains water (50%), organic (28%) and inorganic (22%) substances. Among the latter, most part is calcium phosphate (85%); in much smaller quantities it containes calcium carbonate (10%), magnesium phosphate (1,5%) and calcium fluoride (0,3%). Inorganic substances of dental tissues are represented mainly by hydroxyapatite [Са₃РО₄)₂]₃ • Са(ОН)₂.

1. Preparation of extracts of bone and teeth tissues.

Put 5 g of bone tissue in the flask, pour 25 ml of 0,5% sulfuric acid solution and leave for a day. Inorganic substances transfer into solution. Extract is filtered.

A sample of 0.5 g of the tooth is placed in a flask. Add 30 ml of 10% hydrochloric acid solution and boil in the ventilating box. When a tooth is completely dissolved, the flask contents is cooled and filtered.

2. The detection of calcium ions. To 2 ml of extract 3-4 drops of a saturated solution of ammonium oxalate was added. Calcium oxalate is precipitated:

3. The detection of magnesium ions. Calcium oxalate obtained in the previous experiment, isolated by filtration. Add 3-4 drops of concentrated ammonia solution to the filtrate. There is a precipitate of magnesium ammonium phosphate:

MgHPO₄ + NH₄OH  MgNH₄PO₄ + H₂O

4. The detection of phosphoric acid. To a few milliliters of the filtered extract 5 – 6 drops of molybdenum reagent is added and heated to boiling. Slowly, a yellow crystalline precipitate of ammonium phosphomolybdate is forming:

12 (NH₄)₂MoO₄ + H₃PO₄ + 21 HNO₃  (NH₄)₂PO₄12MoO₃ +

+ 21 NH₄NO₃ + 12 H₂O