BIOS 281 Lecture 3 Membrane Transport and Potentials

A cells rmp is created using ion gradients and a

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Unformatted text preview: one for the treatment of heart failure for decades and is the only oral inotropic support agent currently used in clinical practice. (5) Membrane Poten0als and Ac0on Poten0als Under normal circumstances inside outside + K Na+ + Na ATP K+ 3 Na+ 2 K+ ADP Remember: sodium is pumped out of the cell, potassium is pumped in... Inside of cell is slightly nega0ve. Why? K+ N a+ outside K+ N a+ inside We can measure these differences! So What? •  Our cells, notably our EXCITEABLE cells/0ssues (Muscle, Nervous) can capitalize upon these differences in charge and use them communicate with one another using two types of electrical signals: –  Graded poten-als are used for short- distance communica0on only. –  Ac-on poten-als allow communica0on over long distances within the body. Electrical Signals in Neurons •  Producing electrical signals in neurons depends on the existence of a res0ng membrane poten0al (RMP) - similar to the electrical poten0al of this 9 v bahery which has a gradient of 9 volts from one terminal to another. –  A cell’s RMP is created using ion gradients and a variety of ion channels that open or close in response to specific s0muli. –  Because the lipid bilayer of the plasma membrane is a good insulator, ions must flow through these channels. Electrical Signals in Neurons •  Ion channels are present in the plasma membrane of all cells in the body, but they are an especially prominent component of the nervous system. •  Much of the energy expended by neurons, and really all cells of the body, is used to create a net nega0ve charge in the inside of the cell as compared to the outside of the cell. A cell’s RMP is created using ion channels to set-up transmembrane ion gradients. Electrical Signals in Neurons •  When ion channels are open, they allow specific ions to move across the plasma membrane, down their...
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This note was uploaded on 11/12/2013 for the course BIOS 281 taught by Professor Varamini during the Fall '12 term at Biola University.

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