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24 Cards in this Set
- Front
- Back
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what is Electrical potential? |
potential difference in electrical charge between 2 points in an electrical feild. Measured in MV |
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what is a MEMBRANE POTENTIAL ? |
the electrical difference accross the plasma membrane only |
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What are the 3 types of potential? |
Resting membrane potential Action potential Graded potential |
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Why is RMP important ? |
for maintaining ionic and hydrostatic equilibrium in the cell |
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In RMP what are the MV for all different cells? |
Excitable cells -70mv (neurons) -90mv (muscle) Non-excitable cells -20 (epithelial) -40mv (all other cells) |
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What is an Action potential? |
the nerve impulse- occurs in neurons, muscle and glandular cells. The cell breify depolarises |
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what is a graded potential? |
localised changes in the membrane potential |
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3 factors that determine movement accross the cell membrane? |
Polarity- to create an electrical gradient Concentration- create a chemical gradient Membrane permeability- slectively and differenctially |
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Generation of the RMP |
Neg charge proteins and Pi intracellulary (Na+ wants to influx following its electrical gardient) Concentration K+ channels are open- membrance is permeable to K+, infux/efflux easily. follows its electrical gradient in and chemical gradient out. |
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RMP is generated when there is what 3 things? |
Intracellular neg charge (Pi and proteins) Na+ accumulated on the extracellular surface Equal movement of K+ (electrochemcial gardient) These characteristics make the outside of the cell membrane + and the inside - The RMP is generated |
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Maintenance of RMP. What can disturb RMP |
leaking Na+ channels depolarizastion |
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what is Lysis? |
Ruptured cell from too much fluid |
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What pump restores RMP |
Na+/K+ ATPase pump! |
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what is electricc=al charge in a cell measured in? |
mv |
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RMP is generated by? |
ionic movement accross the plasme membrane |
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Membrane permeability in RMP selectively permeable to... |
Specificty of the channel- what ion |
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RMP differentially permeable... |
when will it open close- stimulated by changes in membrane potential, voltage-gated channels, or the binding of a ligand. |
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RMP differentially permeable... |
when will it open close- stimulated by changes in membrane potential, voltage-gated channels, or the binding of a ligand. |
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What is RMP |
the difference in electrical charge accross the plasma membrane, recorded in MV |
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What determines RMP |
RMP has chemical disequilibrium of the cations and electrical disequilibrium chemical and electrical disequilibrium is determined by membrane permeability to specific solutes |
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What makes a cell neg inside? |
Negatively charged proteins and Pi's, they cannot leave the cell because they are too large, and cannot difuse because they are hydrophillic/lipophobic, and a charge cannot diffuse |
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At RMP Na+ levels are |
15mmol/L / 150mmol/L |
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At RMP what are K+ levels? |
150mmol/L / 5mmol/L |
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Why maintain RMP? |
Accumulated Na+ excerts an electrochencial gradient pressure Na+ gets through leakage channels and into the cell- the added + charge can destroy RMP- Adversly affectingionic and osmotic balance- leading to Lysis. Na+ has to be moved back by accross the membrane against its gradient. |
