TAILIEUCHUNG - Ebook Cellular physiology and neurophysiology (2th edition): Part 2

(BQ) Part 2 book "Cellular physiology and neurophysiology" presents the following contents: Active transport, physiology of synaptic transmission, synaptic physiology ii, molecular motors and Muscle contraction, excitation-contraction coupling in muscle, mechanics of muscle contraction. | 11 ACTIVE TRANSPORT OBJECTIVES 1. Understand how the Na pump uses energy from ATP to keep Na i low and K i high by transporting Na and K against their electrochemical gradients. 2. Understand how Ca2 is sequestered in the sarcoplasmic and endoplasmic reticulum and transported across the plasma membrane by ATP-dependent active transport systems. 3. Understand how intracellular Ca2 is controlled and Ca2 signaling is regulated by the cooperative action of many transport systems. 4. Understand the roles of ATP-dependent transport systems in the transport of such ions as protons and copper as well as a variety of other solutes. 5. Understand how different transport systems in the apical and basolateral membranes of epithelia which separate two different extracellular compartments act cooperatively to effect net transfer of solutes and water across epithelial cells. PRIMARY ACTIVE TRANSPORT CONVERTS THE CHEMICAL ENERGY FROM ATP INTO ELECTROCHEMICAL POTENTIAL ENERGY STORED IN SOLUTE GRADIENTS In Chapter 10 we learned how energy stored in the Na electrochemical gradient can be used to generate concentration or electrochemical gradients for other coupled solutes. This is called secondary active transport because a preexisting electrochemical energy gradient is dissipated in one part of the transport process . the downhill movement of Na to generate the chemical or electrochemical gradients of other solutes . glucose or Ca2 . There is no net expenditure of metabolic energy by these transporters. The question we need to address here is How does the Na concentration gradient typically Na o Na i 10 to 15 become established in the first place This brings us to the role of ATP in powering primary active transport. During active ion transport adenosine triphosphatases ATPases interconvert chemical phosphate bond energy and electrochemical potential ion gradient energy. These straightforward chemical reactions can depending on the concentrations of substrates and products .

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