How is selective reabsorption acheived in the kidneys?

In the cells lining the proximal convoluted tubule, sodium-potassium pumps present in the membrane in contact with tissue fluid pump sodium ions out of the cells. This lowers the concentration of sodium ions in the cell cytoplasm thereby causing sodium ions to enter the cells, accompanied by a glucose molecule or an amino acid, from the lumen down a concentration gradient by facilitated diffusion. The concentration of amino acids and glucose inside the cell therefore increases and they then diffuse down a concentration gradient into the tissue fluid. Water follows the path of these molecules as it moves down the water potential gradient. These substances then diffuse into the blood from the tissue fluid and are carried away to where they are needed.

Answered by Nianqi S. Biology tutor

11711 Views

See similar Biology A Level tutors

Related Biology A Level answers

All answers ▸

Why do enzymes only catalyse specific reactions?


Explain how the cardiac cycle pumps blood around the body


What are the main components and properties of a plasma membrane?


Explain how the structure of an enzyme allows for it to act as a biological catalyst


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo
Cookie Preferences