Ion Channels Flashcards
What are ion channels classified by?
Selectivity
Gating
Regulation
What are voltage dependent channels?
They open or close depending on the membrane potential
What is the patch clamp technique used for?
Directly measurng ion channel function and evaluation of ion channel pathophysiology and mutations
How does the patch clamp technique work?
Pipette filled with salt soluton and a silver electrode touches cell membrane and sucked so that it is sealed
Allows you to look at single ion channel currents and when they are opening and closing
How are ion channels and the nernst potential of an ion linked?
When ion channels are open they help drive the membrane potential towards the nernst potential
How can ion channel currents be identified?
By measuring the total current flow across the membrane using the patch clamp technique and clamping to a specific potential
Channel blockers can be added to determine what ones are present
What are the different types of cell membranes?
Neuronal
Epithelial
Muscle
Endocrine
What is the membrane potential of most cells in the body?
-70mV
How is resting membrane potential created?
Concentration gradient moves K+ ions out which creates a opposite potential gradient that moves them inwards until there is equal movement in and out
The potential this happens at is the Nernst potential
Flow of Na+ ions in and out of cell
High extracellular Na+ and low intracellular Na+
Concentration gradient drives ions into the cell
What is the relationship between potential and concentration gradients?
Accumulation of positive charge in the cell stops some of them coming in so potential and concentration gradients work against each other
Why is regulating intracellular Na+ important in epithelial cells?
Thick ascending limb of loop of henle- creation of transepithelial osmotic gradient
Activity of NKCC depends on inward Na+ gradient
Why is regulating intracellular Na+ in excitable cells important?
Increase in Na+ would cause decrease in inward chemical gradient so would take longer for potentials to develop
Problems with propagation of AP and slower conduction
What is the Na+/K+ pump coupled to?
Hydrolysis of 1ATP
What is the purpose of the Na+/K+ pump?
Maintaining a low intracellular Na+ concentration and a high intracellular K+ concentration
