The resting membrane potential

17 The resting membrane potential





Questions



image How do cells maintain the resting membrane potential?

image What are the relative contributions of Na+/K+-ATPase and voltage-insensitive K+ channels in setting membrane potential?

image How do cells change the resting membrane potential?


Membrane potential


All cells have an electrical potential difference across their plasma membrane (membrane potential). This is always expressed as the voltage inside relative to that outside the cell. Animal cells have resting membrane potentials ranging from approximately −20 to −90 mV depending on the cell type (Fig. 3.17.1). Changes in this potential difference form the basis of electrical signalling in cells.


image

Fig. 3.17.1 Development of the resting membrane potential.



The resting membrane potential


At rest, cell membranes are more permeable to K+ than to other ionic species because of facilitated diffusion through K+ channel proteins, which form K+-specific pores in the membrane. The extracellular and intracellular K+ concentrations in a ‘typical’ cell are 4.5 and 160 mmol/l, respectively; therefore, K+ tends to move outwards down its concentration gradient. Since large protein anions inside the cell are unable to follow K+

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Jun 18, 2016 | Posted by in BIOCHEMISTRY | Comments Off on The resting membrane potential

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