In this lab, students do a cobalt backfill of the nerve from which they recorded in lab 2. This lab introduces intracellular recording of the crayfish abdominal superficial flexor muscle. While honing intracellular recording skills, students change sodium and potassium ion concentrations in the extracellular fluid to show dependence of resting potential on potassium ions. The brain of the snail Helix aspersa has many large cells with interesting properties. Students usually see sodium and calcium action potentials, spontaneous firing, and rhythmic bursting.
Students can investigate neural excitability by injecting current.
This lab takes up where lab 5 leaves off. Students examine the ionic basis of snail action potentials by altering ion concentrations and by pharmacological manipulation. Figures and videos are the same as in Lab 5. The freshwater alga Chara corallina fires action potentials when electrically stimulated. This illustrates the wide taxonomic distribution of voltage-gated channels and excitability.