Neuronal Synapses (Chemical) Saltatory Conduction in Neurons. Electrotonic and Action Potentials. Correction to Sodium and Potassium Pump Video. Sodium Potassium Pump. Anatomy of a Neuron. Hemoglobin. Circulatory System and the Heart. Red blood cells. Diffusion and Osmosis. The Lungs and Pulmonary System.