Sound waves are collections of air molecules that are either more or less _______ than molecules of ambient air.

The inner ear’s cochlea is filled with _______; its vibrations open and shut “trapdoor” channels on _______ cells, thus resulting in the transmission of a nerve signal.

Each of our senses employs the cells known as _______, which can both respond to stimulation and transform their responses into _______.

All senses except _______ route their signals through the brain’s______, after which these signals go to differing parts of the _______ for additional processing.

The 340 to 380 types of olfactory receptors we have allow us to discriminate among a much greater number of smells because the various receptor types can send signals in different _______.

The spinal cord can receive input from _______and direct ________ in response, without input from the brain. This entire process is known as a_______.

The autonomic nervous system is divided into the sympathetic or “_______” division and the parasympathetic or “_______” division.

The portion of the brain that is the site of our highest thinking and processing, the _______, is the outer portion of the brain’s _______.

Transmission of a nerve signal down an axon takes advantage of something called a resting potential, which can be defined as a difference in _______ that exists between the inside and the outside of a neuron in a resting state.

The key to signal transmission down the length of an axon is that an influx of Na+ ions at an initial location on the axon membrane triggers an influx of _______ on a _______ of the membrane.

Communication between neurons takes place by means of substances called _______moving across a ________ from a sending cell to a receiving cell.