Answer: nephron.
- A nephron
- B neuron
- C alveolus
- D villus
Correct answer: A. nephron
Explanation: Each kidney contains about a million nephrons that filter blood.
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.
Read the full Excretory Products and their Elimination notes →