Ion movement, hydrogen

Figure 15-6. Mechanisms of sodium, potassium, and hydrogen ion movement and water reabsorption in the collecting tubule cells. Synthesis of Na+/K+ ATPase and sodium and potassium channels is under the control of aldosterone, which combines with an intracellular receptor, R, before entering the nucleus. ADH acts on its receptor, V, to facilitate the insertion of water channels from storage vesicles into the luminal membrane. (Reproduced, with permission, from Katzung BG [editor] Basic Clinical Pharmacology, 8th ed. McGraw-Hill, 2001.)...

The electrolyte thus formed can conduct electric current by the movement of ions under the influence of an electric field. A cell using an electrolyte as a conductor and a positive and a negative electrode is called an electrolysis cell. If a direct-current voltage is appHed to a cell having inert electrode material such as platinum, the hydrogen ions (cations) migrate to the cathode where they first accept an electron and then form molecular hydrogen. The ions... 

Sour and salty. Within the membrane of the taste cell are ion channels which control the movement of ions, such as sodium, potassium and calcium, into and out of the cell. Sour taste sensations are in part due to the effect of hydrogen ions however, some taste is also a function of the hydrophobicity of the organic acid, such as citric acid (18). Acids can produce a decrease in potassium ion conductance (depolarization) in the membrane. 

In ice a chain of hydrogen-bonded water molecules links the hydroxide and the hydrogen ions (Eq. 9-94). By synchronous movement of electron pairs from the OH ion and from each of the water molecules in the... 

Here (BChl)2 stands for the special pair of bacteriochlorophyll molecules, UQ for ubiquinone, and Cyt for the cytochrome protein. Steps 1 and 3 involve excitation of bacteriochlorophyll and transfer of a pair of electrons to a ubiquinone molecule. Steps 2 and 4 restore the special pair to its initial state. Steps 5 and 6 transfer hydrogen ions outside the membrane wall and restore the cytochrome to its reduced form. The net reaction is the light-driven movement of hydrogen ions from inside the cell to outside the cell. 

Oxidative phosphorylation The process by which adenosine triphosphate (ATP) is synthesized from a hydrogen ion gradient across the mitochondrial inner membrane. The hydrogen ion gradient is formed by the action of protein complexes in the mitochondrial membrane that sequentially transfer electrons from the rednced cofactors nicotinamide adenine dinucleotide (NADH) and FADH to molecnlar oxygen. Movement of hydrogen ions back into the mitochondrion via ATP synthase drives the synthesis of ATP. 

Except for those cases where ionic hydroxides dissolve in water to form free hydroxide ions, the behavior and strength of acids and bases are due to their ability to cause hydrogen ions to move to water molecules from an acid or from water molecules to a base. This movement of hydrogen ions between particles in solution can be used to demonstrate different types of acid-base reactions. 

The theory universally held at the present time is that conduction in metals is due to the movement of electrons. These arc the units of negative electricity, and have a mass of about 1/1S00 of that of the hydrogen ion, and a charge of 4.770 X 10 10 electrostatic units of electricity. A current of electricity in a metallic conductor is therefore due to a stream of electrons moving in the contrary direction to what is usually known as the "direction of the current/ More precisely, a galvanic current is due to superposing of a definite shift of the electrons in one direction on the random, or unordered, motion of the electrons in the metal. 

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