Changing levels of certain substances in the blood, such as sodium, can cause confusion. Increased heart rate...heart palpitations, which feel like your heart is racing or throbbing. To make up for the loss in pumping capacity, the heart beats faster.
The pitch plane of a pair of gears is the plane perpendicular to the axial plane and tangent to the pitch surfaces. A pitch plane in an individual gear may be any plane tangent to its pitch surface.
Pitch is sometimes defined as the fundamental frequency of a sound wave (i.e. generally, the lowest frequency in a given sound wave). For most practical purposes, this is fine, and pitch and frequency can be thought of as equivalent. On the other hand, for most practical purposes, amplitude can be thought of as volume.