Chapter 4 Mechanoreceptors: Touch and Hearing

olfactory

relating to the sense of smell

enzyme cascade

A series of reactions, often involved in regulatory events, in which one enzyme activates another (often by phosphorylation), which activates a third, and so on. The effect of a catalyst activating a catalyst is a large amplification of the signal that initiated the cascade.

directly gated receptor cells

cells with receptor proteins that are directly opened by the stimulus

second messenger receptor cells

receptor cells that utilize a cascade of reactions for moderating stimuli

receptor potential

A slow, graded electrical potential produced by a receptor cell in response to a physical stimulus

mechanoreceptors

respond to touch, pressure, vibration, and stretch

Pacinian corpuscles

respond to deep pressure and vibration

epithelial

A body tissue that covers the surfaces of the body, inside and out

myelinated

having a myelin sheath

monopolar neuron

Neuron with a single branch extending in two directions from the cell body

dorsal root ganglia

clusters of sensory neurons outside the spinal cord

micrometer

one millionth of a meter

tetrodotoxin

Toxin: very potent sodium channel blocker; blocks action potential propagation in nerve, heart, and skeletal muscle. From puffer fish, California newt. Tox: paresthesias, paralysis

conductance

the ease with which ions flow through a channel