Question

Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.

Answer 1

Alveoli		Nephrons
(i)	Alveoli are tiny, balloon-like structures found in the lungs.	(i)	Nephrons are tubular structures located within the kidneys.
(ii)	The walls of the alveoli are one cell thick and are rich in capillaries.	(ii)	Nephrons consist of the glomerulus and Bowman's capsule, forming a long renal tube.

Gas exchange (CO₂) occurs between the blood in the capillaries surrounding the alveoli and the gases within the alveoli. (i) Blood enters the kidneys via the renal artery, which then branches into numerous capillaries within the glomerulus. Water and solutes are transferred from the blood to the nephron at Bowman's capsule.

Subsequently, the filtrate travels through the proximal tubule, descends into the loop of Henle, and then moves to the distal tubule. Finally, the filtrate enters the collecting duct, which aggregates urine from multiple nephrons and directs it to the ureter. Throughout this process, essential substances like glucose, amino acids, and water are selectively reabsorbed from the filtrate.