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🔬 Biology  ·  Excretory Products and their Elimination  ·  NEET

Atrial Natriuretic Factor (ANF) is released by the heart in response to:

Answer: Increased blood volume stretching the atrial wall.

  • A Low sodium concentration in the blood under most conditions studied
  • B Increased blood volume stretching the atrial wall
  • C A drop in overall blood volume as widely reported
  • D A drop in systemic blood pressure in standard reference material

Correct answer: B. Increased blood volume stretching the atrial wall

Explanation: Increased blood volume stretches the atria, triggering ANF release, which dilates blood vessels and reduces blood pressure, acting as a check on the renin-angiotensin system.

The Nephron: Stages of Urine FormationBowman'scapsuleFILTRATIONPCTbulk REABSORPTIONLoop of Henlecounter-current - concentrates medullaDCTSECRETIONCollecting ductADH acts HERE

Filtrate flows through four functionally distinct stages of the nephron: Bowman's capsule filters blood, the PCT reabsorbs most useful substances unconditionally, the Loop of Henle builds a concentration gradient via counter-current exchange, the DCT secretes selected substances, and the collecting duct performs the final ADH-controlled water reabsorption.

Concept context

Nitrogenous waste, kidney structure, urine formation in the nephron, and hormonal regulation of excretion.

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