BFQ9 Potenciales 2
Understanding Membrane Potentials
The discussion delves into the concept of membrane potentials, focusing on the differences between external and surface potentials in phases Alpha and Beta solutions.
External Potential vs. Surface Potentials
- External potential is termed as membrane potential when a biomembrane separates aqueous solutions with different compositions.
- Surface potentials near biological membranes are negative due to anionic lipid components, influenced by ionic composition.
- Surface potentials consist of two components: negative potential near the membrane surface and an interior potential due to ordered dipolar molecules forming the membrane.
Determining Membrane Potentials
Exploring methods for determining membrane potentials, focusing on surface potentials and their implications within biological membranes.
Determining Surface Potentials
- Initial studies involved measuring conductivities of hydrophobic ions within a bilayer setup to understand internal membrane potentials.
- Anions showed higher conductivity than cations, indicating greater permeability of membranes to anions due to partition differences.
- Positive charge density inside the membrane leads to higher anion partitioning, resulting in a 10^2 mV potential difference across the membrane.
Models for Charged Interfaces
Discussing models describing charged interfaces and ion distributions near surfaces, highlighting early theories like Helmholz and Perrin's model.
Helmholz and Perrin Model
- Helmholz and Perrin proposed a model where cations form a layer opposing the negatively charged surface, effectively screening it.
Detailed Explanation of the Diffuse Layer Model
In this section, the speaker discusses the limitations of a model that neglects thermal agitation in solutions and introduces Gay and Chapman's diffuse layer model as a solution to this issue.
Introduction of the Diffuse Layer Model
- The current model fails to consider that species and molecules in a solution experience thermal agitation.
Gay and Chapman's Proposal
- Gay and Chapman proposed the diffuse layer model to address the impact of thermal agitation on species in a solution.