Active Transport -

SGLT1 in the small intestine absorbs dietary glucose. Patients with mutations in SGLT1 suffer from severe glucose-galactose malabsorption.

The Na⁺/K⁺ pump restores resting membrane potential after an action potential. Inhibition (e.g., by ouabain) stops nerve signaling. active transport

Diabetic drugs (SGLT2 inhibitors like empagliflozin) block glucose reabsorption in the kidney, lowering blood sugar. Proton pump inhibitors (omeprazole) block gastric H⁺/K⁺-ATPase to reduce stomach acid. SGLT1 in the small intestine absorbs dietary glucose

| Feature | Passive Transport | Active Transport | | :--- | :--- | :--- | | | None (kinetic energy) | ATP, light, or redox energy | | Direction | Down gradient (high → low) | Against gradient (low → high) | | Carrier proteins | Channel proteins or uniporters | Pumps, symporters, antiporters | | Equilibrium | Reaches equilibrium | Maintains steady-state disequilibrium | | Example | O₂ diffusion, water osmosis | Na⁺/K⁺ pump, glucose uptake in intestines | 3. Primary Active Transport Primary active transport directly couples a chemical reaction (e.g., ATP hydrolysis) to solute movement. 3.1 The Sodium-Potassium Pump (Na⁺/K⁺-ATPase) Located in the plasma membrane of animal cells, this pump is the archetype of primary active transport. It exports 3 Na⁺ ions out of the cell and imports 2 K⁺ ions inward per ATP hydrolyzed. This creates an electrochemical gradient: a high extracellular Na⁺ and high intracellular K⁺. Inhibition (e

The Mechanisms and Significance of Active Transport in Cellular Physiology