• 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
The Neuronal Membrane at Rest
• The CAST OF CHEMICALS
– Cytosol and Extracellular Fluid – The Phospholipid Membrane – Protein
• The MOVEMENT OF IONS
– Diffusion – Electricity
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
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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.
Neuronal Electric Activit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 – Electricity
• THE IONIC BASIS OF RESTING MEMBRANE POTENTIAL
– 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
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
Concentration
• CONCLUDING REMARKS
Cytosol and Extracellular Fluid
• Water:
– Its uneven distribution of electrical charge, so H2O is a polar molecule
• Ions:
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
– 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
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
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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
– Post-Synaptic Potential
• Excitatory Post-Synaptic Potential • Inhibitory Post-Synaptic Potential
– End-plate Potential – Receptor Potential
Chapter 3