3. The Na+-K+ ATPase Pump

4. Cardiac glycosides:
plant and animal steroids
Ouabain!
Digitalis!:
increased Na+ conc inside heart leads to stimulation of Na+-Ca2+ exchanger, which extrudes sodium in exchange for inward movement of calcium. Increased intracellular Calcium stimulates muscle contraction.

5. The Na+-K+ ATPase Pump: Mechanism

6. Response of a human RBC to changes in osmolarity of the extracellular fluid

7. The Na+-K+ ATPase Pump is required to maintain Osmotic Balance and Stabilize Cell Volume Sources of Intracellular Osmolarity: large number of counterions (inorganic ions of opposite charge) that are attracted to large macromolecules (most are charged). small metabolites (high concentration of small organic molecules, sugars, amino acids, nucleotides) and their counterions Sources of Extracellular Osmolarity: Due mainly to small inorganic ions - these leak slowly across the plasma membrane into the cell The problem: Because of above factors, water moves into the cell by osmosis The Solution: Na+-K+ ATPase Pump

8. In vitro Investigation of The Na+-K+ ATPase Pump

9. Control of acid secretion in the stomach

10. Potassium channel

12. The Potassium Channel

13. Hinge-bending Model for the opening of the Bacterial KcsA Channel.

16. The Structure of One subunit of a eukaryotic, Voltage Gated K+ Channel (Drosophila Shaker K+ Channel)

17. 3-D Structure of a Voltage Gated Mammalian K+ Channel

19. Conformational States of a Voltage Gated K+ Ion Channel

20. A typical ion channel fluctuates between open and closed states

21. The gating of ion channels

22. The technique of patch clamp recording Measuring Ion Channel Conductance

23. Patch Clamp Recording

24. Patch Clamp Recording

26. The ionic basis of membrane potential

33. The membrane potential in animal cells depends mainly on K+ Leak channels and the K+ gradient across the plasma membrane

34. dGconc= -RT ln [Co] [Ci]

35. dGvolt=zFV

36. dGconc + dGvolt = 0 Ion distribution is at equilibrium across the membrane

37. The Nernst Equation and Ion Flow V= RT ln Co zF Ci

38. The Resting Potential decays only slowly when the Na+ K+ Pump is stopped