26. Which of the following does not contribute to the interstitial osmotic gradi

Question

26. Which of the following does not contribute to the interstitial osmotic gradient in the kidney medulla? a. The single effect b. Counter current multiplier c. The Length of the loop of Henle d. All of the above 27. The Brazilian pit viper venom causes a fatal drop in its victim's blood pressure. How does this venom act? a. It activates ACE, an enzyme that generates angiotensin II b. It inhibits ACE, an enzyme that generates angiotensin II c. It leads to increased ADH levels d. It increases blood volume 28. Which of the following is an adaption that frogs living on land employ to cope with evaporative water loss? a. Some frogs store and retrieve water from urine in their bladders b. Frogs absorb water through pelvic patches on their underbelly c. Tree frogs smear lipids on their integuments d. All of the above

Explanation / Answer

26. d. All of the above

Kidney has some unique anatomical arrangements called counter current system, which are responsible for the development and maintainance of medullary gradient and hyperosmolarity of interstitial fluid in the inner medulla. Single effect which is derived by active transport of sodium chloride out of the tubular fluid in the thick ascending limb into the interstitial fluid which makes it hyperosmotic. Hence, option a is correct.

Counter current multiplier which comprises of opposite flow of fluid in the descending limb and the ascending limb in the U shaped loop of henle, and long length of loop of henle which extends upto deeper parts of medulla also accounts for hyperosmolarity of medullary interstitial fluid. Hence, option b, c are also correct

So, the correct answer is d. All of the above

27. b. It inhibits ACE, an enzyme that generates the angiotensin II

Brazilian pit viper venom contains peptides which act as Angiotensin converting Enzyme inhibitor that prevents the formation of Angiotensin II, a potent vasoconstrictor. As a result of which, the Renin angiotensin system of blood pressure homeostasis is impaired leading to fall in blood pressure which is beyond the control of repair by the body and turns out to be fatal. Hence, the correct answer is b

Option a is false since activation of ACE causes generation of Angiotensin II which leads to vasoconstriction and increase in blood pressure but not drop in blood pressure. Option c, d also results in increase in blood pressure due to water, sodium reabsorption (by ADH) and hypervolemia respectively. Hence, not correct

28. d. All of the above

In order to survive on the land, some frogs store the water in their bladder while in water and reclaim the same water from bladder if there is water scarcity when on land. Hence, option A is correct

Frogs also absorb water through the seat patch (belly skin) which accounts for 10% of the total skin that also serves as an adaptation. Hence, option b is also correct

Tree frogs smear lipids on their integuments that prevent evaporative water loss which is also correct. So, the correct choice is option d all of the above

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