Biology: Fundamentals of Neuronal Function Flashcards
Examples of excitable cells
How do excitable cells do work?
Excitable cells use potential energy to do work
Differences in ion concentrations across nerve cell membranes provide the potential energy required to transmit nerve impulses.
These are ______
Action potentials
How do we measure membrane potential?
Intracellular Recording
Measurement of voltage/current across cell membrane
Involves microelectrodes inserted in the cell + reference electrode outside the cell
What is the plasma membrane potential (Vm)?
-70 mV
All cells have a resting membrane potential, however, it varies with cell type.
What are the differences?
In some cells, it remains static (no change) e.g. homeostasis + substrate transport
In others, plasma membrane potential (Vm) changes with signal transduction + action potential
How does charge separate across plasma membrane?
How does sodium pump (Na+/K+-ATPase) work?
- 3 Na+ bind to the transporter
- Conformational change stimulates phosphorylation
- Further conformational change
- Na+ leaves cell
- 2 K+ binds to the transporter + stimulates dephosphorylation
- Reverts back to original conformation
- K+ is released into the cytoplasm
Which ion leaves crosses cell membrane with ease?
K+ leaves cells with ease compared tp Na+
What causes resting membrane potential?
It is due to the separation of electrical charges across cell membrane.
Vm = -70 mV
Inside + outside of the cell at resting membrane potential is electrically neutral.
How is this done?
Describe leak channels
What is the effect of voltage on ion movements?
Describe electrochemical equiibrium
Define equilibrium potential
What is equilibrium position?
No net force. no net ion flow
What is K+ equilibrium potential?
If a cell membrane is solely permeable to K+, what is the plasma membrane potential?
What is equilibrium potential also called + how is it described?
Which equation is the most realistic in terms of approximation of membrane potential?
What is Pion + how is it measured?
If overall concentration doesn’t change, how is membrane potential controlled?
Ion permeability changes due to opening + closing of ion channels in membrane
