voltage gated ion channels Flashcards
What are voltage-gated ion channels?
Ion channels that open or close in response to voltage across the membrane.
What are ligand-gated channels?
Channels that open or close in response to the binding of a chemical messenger (ligand).
Where are mechanically-gated ion channels found?
In the skin and inner ear.
What is the function of metabotropic receptors?
They use signal transduction mechanisms to activate intracellular events without forming an ion channel pore.
What ion is primarily dependent on voltage-gated Na+ channels?
Na+
What ion is primarily dependent on voltage-gated K+ channels?
K+
What role does Ca2+ play in voltage-gated ion channels?
Transduces membrane potential changes into intracellular Ca2+ transients that initiate physiological events.
What is the primary structure of voltage-gated Na+ and K+ channels?
4 domains with 6 transmembrane segments each.
What are the voltage sensors in Na+ and K+ channels?
TM4.
What is the inactivation gate in voltage-gated channels?
Linker loop between III and IV.
What is the role of beta subunits in voltage-gated channels?
They have a modulatory role.
What occurs at Site A during action potential propagation?
Opening of voltage-gated Na+ channels and membrane depolarization.
What happens during the refractory period in action potential propagation?
VG Na+ channels are inactivated and VG K+ channels are activated.
How do K+ channels behave in relation to Na+ channels during depolarization?
K+ channel opens with a delay relative to Na+ channels.
What pathologies are associated with Na+ channels?
Hyperexcitability, impaired muscle relaxation, paralysis, and seizure disorders.
