Anatomy Exam 2 - Excitability

Anatomy Exam 2 - Excitability 2 characteristics of the plasma membrane -Answer-- ions not equally distributed across membrane - unequally permeable to various ions voltage of a typical cell -Answer-negative inside of the cell is more negative than the outside of the cell inside(-) : outside(+) K+ concentrations -Answer-in: 100 out: 5 K+ mV (equilibrium potential) -Answer--75 mV Cl- concentrations -Answer-in: 10 out: 105 Cl- mV - equilibrium potential -Answer--59 mV Na+ concentrations -Answer-in: 10 out: 100 Na+ mV - equilibrium potential -Answer-+58 mV anions concentrations -Answer-in: 100 out: 0 Ca++ concentrations -Answer-in: 0.0001 out: 1.2 what ion is the membrane most permeable to at rest -Answer-K+ attractive forces characteristic electrostatic -Answer-only work over short distances strong requires energy to oppose the force 2 opposing forces set membrane potential -Answer-- concentration gradient - electrical potential (electrostatic force) force of concentration gradient -Answer-pushes ions towards chemical equilibrium electrical potential force -Answer-pushes ions towards electrostatic equilibrium charge of ion - attract/repel what is equilibrium potential -Answer-the membrane potential at which the concentration gradient and electrical potential forces are equal/opposite FOR ONE ION all ions have unique equilibrium potentials the voltage each ion wants the membrane to be at common misconception of equilibrium potentials -Answer-ions move, but relative concentration of ions do not change - blue food dye into the ocean (doesnt affect) only relative conc. change in state of disease or in a lab small movements produce ____ changes in voltage Vm -Answer-small changes - big changes in voltage at the membrane - not the entire cell Nernst equation -Answer-Eion = temp/z x (log[ion]outside/[ion]inside) nernst equation z = -Answer-charge of the io