Final answer:
The steps to maintain homeostasis of blood osmolality are glomerular filtration, reabsorption, secretion, and excretion, which corresponds to option (A). These processes filter blood, recover needed nutrients, secrete waste, and excrete urine, balancing blood osmolality.
Step-by-step explanation:
The sequential steps in maintaining homeostasis of blood osmolality through the kidney are glomerular filtration, reabsorption, secretion, and excretion. The correct sequence is therefore (A) Glomerular filtration, reabsorption, secretion, excretion. This is how the kidneys filtrate the blood, regulate the concentration of substances, and maintain homeostasis:
- Filtration occurs at the renal corpuscle (glomerulus and Bowman's capsule), where blood pressure forces water and solutes out of the blood and into the nephron.
- Reabsorption happens primarily at the proximal convoluted tubule (PCT), where essential nutrients and a significant amount of water are reabsorbed into the bloodstream.
- Secretion is the transfer of wastes and excess ions from the blood into the tubule and occurs mostly in the distal convoluted tubule (DCT).
- Finally, the remaining filtrate, which is now urine, is funneled into the renal pelvis for excretion via the ureter to the bladder.
These steps ensure that blood osmolality is kept within the tight range necessary for body homeostasis.