Question

Scientif 2- 3. Students in an animal physiology lab were experimenting with various inmitations of body fluids to see ahe etfects ofadding a base to a sample of the fluid. The experiment yielded the following data: Solution pH after 30 dps pH after 10 drops plH after 20 dps of base Initial pH of solution of base of base Blood plasma 7.35 7.4 7.37 7.39 Urine 6.4 7.5 7 7.2 Synovial fluid 7.39 7.42 7.37 7,4 Stomach secretion 1.5 3 5 Bile 8.5 9.4 10 How are blood plasma and bile different in terms of their response to addition of base and what accounts for this difference? Why does synovial fluid behave similarly to blood plasma? Look at the stomach secretion-what does the initial pH tell us and what does the response to added base tell us?

Answer 1

1.

• Plasma consists of water, dissolved proteins, amino acids, glucose, vitamins, hormones, electrolytes, and carbon dioxide. The hepatic bile consists of water, bilirubin, fats and bile salts.
• The pH of bile changes to more alkaline (pH 8 to 10) on the addition of base. Whereas the blood plasma resists changes in pH when the base is added.
• This is because blood plasma is composed of many buffering agents within it. A buffer controls the change in pH by converting the strong acid or base into a weak one. The proteins present in the plasma act as the main buffering agents. The other buffers include phosphate and carbonates present in the plasma.
• The concentration of bicarbonate in the bile is higher than in the plasma. This is the reason behind the change of more alkaline pH in bile.

2.

• The composition of synovial fluid resembles plasma. It consists of hyaluronan, lubricin, proteins, glucose, uric acid and ultrafiltrate of plasma.
• The buffering property is present in this fluid is also similar to plasma.

3.

• The initial pH of stomach secretion is 1.0. On addition of a base, the pH is increasing to 5.0.
• The stomach secretion consists of water, hydrochloric acid (HCl), organic substances, and electrolytes.
• The initial acidic pH is due to the presence of HCl. Due to the absence of buffering agents, the pH changed to 5.0. This is only in case of in-vitro experiments. In real, inside the stomach, the change in pH of the stomach secretion is controlled by the buffer secreted by the stomach.