Membrane potentials膜电位 Xia Qiang(夏强),PhD Department of physiology Zhejiang University School of Medicine Tel:88208252 Email:xiaqiang@zju.edu.cn
Membrane potentials 膜电位 Xia Qiang（夏强）, PhD Department of Physiology Zhejiang University School of Medicine Tel: 88208252 Email: xiaqiang@zju.edu.cn
LEARNING OBJECTIVES Describe the maintenance of resting potential in a ce Explain how a cell is induced exciting Contrast graded potentials and action potentials Describe how a cell has refractory phase
LEARNING OBJECTIVES • Describe the maintenance of resting potential in a cell • Explain how a cell is induced exciting • Contrast graded potentials and action potentials • Describe how a cell has refractory phase
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display Distribution of Major Mobile Ions TABLE 6-2 Across the plasma membrane f a Typical Nerve cel Concentration, mmol/L ION EXTRACELLULAR INTRACELLULAR Na 150 15 110 K 5 150 A more accurate measure of electrical driving force can be obtained using mEq/L, which factors in ion valence. Since all the ions in this table have a valence of 1. the mEq/L is the same as the mmol/L concentration
Resting membrane potential (静息电位) a potential difference across the membranes of inactive cells, with the inside of the cell negative relative to the outside of the cell difference/mv Ranging from -10 to-100 mv -60 2
Resting membrane potential （静息电位） • A potential difference across the membranes of inactive cells, with the inside of the cell negative relative to the outside of the cell • Ranging from –10 to –100 mV
Overshoot refers to (超射) the development of a charge reversal +60 A cell “ polarized Repolarization is(复极化) because E9g 50> movement back its interior toward the resting potential. Is more negative than its gSN exterior o0 极化) 70 a Resting potential Depolarization occurs Hyperpolarization is when ion Time the development of movement even more negative reduces the charge inside the cell charge imbalance (去极化) (超极化)
Depolarization occurs when ion movement reduces the charge imbalance. A cell is “polarized” because its interior is more negative than its exterior. Overshoot refers to the development of a charge reversal. Repolarization is movement back toward the resting potential. Hyperpolarization is the development of even more negative charge inside the cell. （极化） （去极化） （超极化） （复极化） （超射）