Question

1. ADH regulation of fluid volume and osmolarity of body fluids. What other hormones influence fluid regulation?

2.The carbonic acid – bicarbonate buffer systems role in maintaining pH.

3.The role of the respiratory system in maintaining pH by by exhaling carbon dioxide.

4. How the kidney maintains pH by the excretion of H+, and reabsorption of bicarbonate ions, (taking into account the different parts of nephron where this occurs).

5. Compare and contrast the various types of respiratory and metabolic acid- base imbalances.

Answer 1

Ans1) Apart from ADH, the other hormones which are responsible for maintaining fluid volume aldosterone and atrial natriuretic peptide (ANP) hormone. ADH helps in regulating fluid balance and osmolarity and does so by conserving the amount of water in the body and hence prevents its increased loss in urine. The hormone can bind to the receptors present in the kidney and hence helps in reabsorption of water, reducing the overall formation of urine. The aldosterone is an important hormone which helps in regulating the fluid balance as well as maintain the electrolyte balance. This hormone helps the kidney to retain sodium as well as excrete potassium and hence it helps in regulating the fluid balance. The ANP hormone helps in increasing the excretion of sodium and water and hence it helps in increasing the glomerular filtration rate. It also inhibits the production of angiotensin and aldosterone through inhibition of renin secretion.

Ans 2) The carbonic acid and bicarbonate buffer system helps in maintaining the pH and hence it helps in maintaining the acid-base homeostasis. When there is C02 present, after it combines with H20, it is converted into bicarbonate ion and H+ ion in presence of carbonic anhydrase enzyme. Due to the increase in the concentration of H+ ions in the blood but the buffer system helps in neutralizing the blood either in presence of hydrogen or hydroxide ions. As the pH of the blood reduces, it tends to combine excess H+ to bicarbonate which forms hydrogen carbonate. This leads to increase pH of blood. This is how the balance is maintained.