Action potentials begin by the opening of ligand-activated potassium channels. closing of ligand-activated potassium channels. closing of voltage-activated calcium channels. opening of voltage-activated sodium channels. closing of ligand-activated chloride channels.

Astream of surface water reaches a porous portion of sediment and seeps into the ground. this water eventually joins a large reservoir of water located beneath the earth's surface. the example above describes the interacting with the a. cryosphere; biosphere b. hydrosphere; biosphere c. hydrosphere; geosphere d. cryosphere; geosphere