The process that permits absorption of glucose into cells is primarily facilitated diffusion and active transport. Specifically, glucose absorption into most body cells occurs via facilitated diffusion through glucose transporter proteins (GLUTs). In the small intestine and renal tubules, glucose absorption happens through secondary active transport involving sodium-glucose co-transporters (SGLT), which actively transport glucose against its concentration gradient using energy from sodium ion gradients established by the sodium-potassium pump. Once inside cells, glucose can be metabolized or stored. Insulin plays a key role in increasing glucose uptake by cells, especially muscle and fat cells, by enhancing the number or activity of glucose transporters on the cell membrane. In summary:
- In the small intestine, glucose is absorbed by active co-transport with sodium ions via SGLT1.
- In most body cells, glucose enters through facilitated diffusion by GLUT proteins.
- Insulin regulates glucose uptake by increasing transporter activity.
- The sodium-potassium pump is essential in maintaining the gradient needed for active absorption in intestines and kidneys.
This combination of active transport and facilitated diffusion allows efficient glucose absorption into cells for metabolic use.
