BIO 359K Lecture Notes - Lecture 5: Tectorial Membrane, Freemartin, Aplysia
Document Summary
Topic 5 the nervous system, brain, hormones, and behavior. Echinodermata is placed next to chordates on a phylogenetic chart: both are deuterosome (anus develops near the blastophore), both have internal skeleton. Both seem to have derived from common ancestor. Nervous system sensory, interneurons, and motor neurons. Electric signaling (3 types of membrane potentials): neurons are sitting in sea water, with high concentrations of sodium and chloride ions outside of the cell. Cell membranes and membranes of nerve cells have a small voltage (potential) across the membrane in its normal or resting state. Resting potential balance of electrostatic pressure and diffusion forces (concentration gradient) involving na+, k+, cl-, and anions- (large, negatively charged molecules, usually proteins) on either side of the phospholipid bilayer. Ions (k+ and na+) cannot pass directly through the phospholipid bilayer but movement is controlled by ion channels which can prevent or, by changing conformation, enable the passage of ions.
