Chapter 9: Receptor Responses and Membrane Potential
Chapter Objectives
Define the term chemical signal (or ligand), and list the two main categories into which ligands are placed.
Describe how ligands directly alter membrane permeability.
Describe how ligands interact with receptors to influence G proteins, and list the ways G proteins can produce a response to a ligand.
Describe how ligands interact with receptors to produce intracellular mediator molecules.
Explain how ligands such as insulin produce a response by causing phosphorylation of intracellular proteins.
Explain how ligands that cross the plasma membrane can produce responses by binding to intracellular receptors.
Describe the concentration differences that exist between intracellular fluid and extracellular fluid.
Describe the factors that affect the concentration differences across the plasma membrane for proteins and for potassium (K+ ), sodium (Na+), and chloride (Cl- ) ions.
Define the term resting membrane potential, and explain how it is produced.
Predict and explain the changes that occur in the resting membrane potential as a result of changes in the K+ ion concentration gradient across the plasma membrane, and do the same for changes in the permeability of the membrane to K+ ions.
Explain how ions cross the plasma membrane.
List the characteristics of a local potential, and explain how a local potential gives rise to an action potential.
Explain the role of voltage-gated Na+ and K+ ion channels in the development of action potentials.
Describe the phases of an action potential and the events responsible for each phase.
Define the terms absolute and relative refractory period, and compare their effects on action potentials.
Describe how an action potential is propagated along a cell's membrane.
Define the words subthreshold, threshold, submaximal, maximal, and supramaximal stimuli.
Compare the effect of stimulus strength and stimulus duration on action potential frequency.
Define the term accommodation, and describe the effect of accommodation on action potential frequency.
