离子通道和神经元的电活动

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Two Properties of Ion Channels
• Ion selectivity (离子选择性)
– The diameter of the pore – The nature of the R groups lining it
• Gating (门控特性)
– Channels with this property can be opened and closed-gated by changes in the local microenvironment of the membrane
Ion Pumps (离子泵)
• Ion pumps are enzymes that use the energy released by the breakdown of ATP to transport certain ions across the membrane
Chapter 3
The Neuronal Membrane at Rest
The Phospholipid Membrane (磷脂膜)
The lipids of the neuronal membrane forming:
a barrier to water-soluble ions a barrier to water
头端-极性磷酸盐-亲水
尾端-非极性碳氢化合物 -疏水
Protein – Amino Acids
The Peptide Bond (肽键) and a Polypeptide (多肽)
Figure 3.6 Protein Structure
The tertiary structure
The primary structure The secondary structure The quaternary structure
• The IONIC BASIS OF RESTING MEMBRANE POTENTIAL
– Equilibrium Potential – The Distribution of Ions Across the Membrane – Relative Ion Permeabilities of Membrane at Rest – The Importance of Regulating the External Potassium
Each of the different polypeptides contributing to a protein with quaternary structure is called a subunit (亚基).
Channel Proteins
• Channel protein is suspended in a phospholipid bilayer, with its
– Post-Synaptic Potential
• Excitatory Post-Synaptic Potential • Inhibitory Post-Synaptic Potential
– End-plate Potential – Receptor Potential
Chapter 3
The Neuronal Membrane at Rest
• The CAST OF CHEMICALS
– Cytosol and Extracellular Fluid – The Phospholipid Membrane – Protein
• The MOVEMENT OF IONS
– Diffusion – Electricity
Neuronal Electric Activities 神经元的电活动
主讲教师 刘风雨 万有 神经科学研究所、神经生物学系
Neuronal Electric Activities Include:
• Rest Potential (Chapter 3) • Action Potential (Chapter 4) • Local Potentials
• THE CAST OF CHEMICALS
– Cytosol and Extracellular Fluid – The Phospholipid Membrane – Protein
• THE MOVEMENT OF IONS
– Diffusion – ElectricБайду номын сангаасty
• THE IONIC BASIS OF RESTING MEMBRANE POTENTIAL
– Salt dissolves readily in water because the charged portions of the water molecule have a stronger attraction for the ions than they have for each other
– hydrophobic (疏水的) portion inside the membrane
– hydrophilic (亲水的) ends exposed to the watery environments on either side
Figure 3.7 A Membrane Ion Channel
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Protein
• These proteins provide routes for ions to cross the neuronal membrane. •The resting and action potentials depend on special proteins that span the phospholipid bilayer.
Concentration
• CONCLUDING REMARKS
Cytosol and Extracellular Fluid
• Water:
– Its uneven distribution of electrical charge, so H2O is a polar molecule
• Ions: