The counter-current mechanism in the kidney is primarily associated with which structure?
A. Glomerulus
B. Loop of Henle and Vasa Recta
C. Proximal Convoluted Tubule
D. Collecting Duct
Answer: Option B
Solution (By JKExamLibrary)
The counter-current mechanism involves the Loop of Henle and the vasa recta (blood capillaries surrounding the loop). The flow of filtrate in the two limbs of the Loop of Henle is in opposite directions, and the flow of blood in the two limbs of vasa recta is also counter-current. This mechanism helps maintain a high osmolarity gradient in the medullary interstitium, essential for concentrating urine.
Explanation:
Adenosine triphosphate (ATP) is the universal energy currency of the cell, storing energy in its high-energy phosphate bonds. Hydrolysis to ADP releases energy for cellular work. NADH and FADH₂ are electron carriers in respiration, ultimately used to produce ATP. Glucose is a fuel molecule, broken down to produce ATP. ATP is directly used in processes like muscle contraction and active transport.
Explanation:
ADH (vasopressin) from the posterior pituitary increases water permeability of collecting duct cells by inserting aquaporins, reducing urine volume.
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