Question

(a) Ascending limb of Henle's loop is .......... to water whereas the descending limb is ........ to it.

(b) Reabsorption of water from distal parts of the tubules is facilitated by hormone ............

(c) Dialysis fluid contain all the constituent as in plasma except ........

(d) A healthy adult human excretes (on an average) ..........................gm of urea /day

Answer 1

(a) Henle's loop consists of three parts: Descending limb, Ascending limb, Hair pin bend. Descending limb is permeable to water and impermeable to salt or ions. Ascending limb is impermeable to water and permeable to salt or ions.

Hence, Ascending limb of Henle's loop is impermeable to water whereas the descending limb is permeable to it.

(b) Vasopressin (Antidiuretic hormone, ADH) is secrted by the posterior pituitary. It increases the permeability of the distal convoluted tubules, increasing water reabsorption.

Hence, Reabsorption of water from distal parts of the tubules is facilitated by hormone Vasopressin.

(c) The fluid and solutes in a dialysis process that simply flows through the dialyzer and does not pass through the semipermeable membrane, gets discarded along with removed toxic substances after they flow back out of the dialyzer. It contains sodium, potassium, calcium, bicarbonate, magnesium, chloride and glucose.

Hence, Dialysis fluid contain all the constituent as in plasma except nitrogenous waste.

(d) About 95% of nitrogen is excreted as urea through urine. A healthy adult person normally excretes about 25 - 30 grams of urea per day.