Please help? What is reabsorbed in the proximal tubule?

Question

Glucose by active transport?

I know water is by osmosis.

Are salts? I thought they were only actively transported out at ascending limb.

2nd convoluted tubule?

What is reabsorbed here? more salts by diffusion?

Answer 1

This should answer both questions

As the filtrate passes along the proximal tubule, most of its water and salts are reabsorbed into the blood of the network of capillaries around the tubules. Of other substances, some are reabsorbed completely, others in part, because this portion of the nephron separates substances that must be retained in the body from those destined for excretion in the urine. The function of the proximal tubule is essentially reabsorption of filtrate in accordance with the needs of homeostasis (equilibrium), whereas the distal part of the nephron and collecting duct are mainly concerned with the detailed regulation of water, electrolyte, and hydrogen-ion balance. All of these processes occur in the tubules through both chemical and physical means, and all are subject to hormonal regulation. Although the urine normally differs markedly from filtrate, if tubule function is progressively reduced in experimental situations by cooling or poisoning, the urine will come increasingly to resemble the filtrate. Also, the more rapidly filtration occurs, the less time there is for the urine to be modified during its passage through the tubules.

Answer 2

* Proximal tubule - reabsorbs 65 percent of filtered Na. In addition, the proximal tubule passively reabsorbs about 2/3 of water and most other substances.

    * Loop of Henle - reabsorbs 25 percent of filtered Na.

    * Distal tubule - reabsorbs 8 percent of filtered Na.

    * Collecting duct - reabsorbs the remaining 2 percent only if the hormone aldosterone is present.