Thermoreceptors, which respond to heat or cold, help regulate body temperature by signaling both surface and body core temperature.
In humans, pain receptors, or nociceptors, are a class of naked dendrites in the epidermis.
They respond to excess heat, pressure, or chemicals released from damaged or inflamed tissues.
The mechanoreceptors responsible for hearing and equilibrium detect moving fluid or settling particles
Hearing and perception of body equilibrium are related in most animals.
Settling particles or moving fluid are detected by mechanoreceptors.
Most invertebrates maintain equilibrium using sensory organs called statocysts.
Statocysts contain mechanoreceptors that detect the movement of granules called statoliths.
The statocyst of an invertebrate
Ciliated receptor cells
Many arthropods sense sounds with body hairs that vibrate or with localized “ears” consisting of a tympanic membrane and receptor cells
In most terrestrial vertebrates, sensory organs for hearing and equilibrium are closely associated in the ear.
Hair cell bundle from a bullfrog; the longest cilia shown are about 8 µm (SEM).
Auditory nerve to brain
Organ of Corti
To auditory nerve
Axons of sensory neurons
Vibrating objects create percussion waves in the air that cause the tympanic membrane to vibrate.
Hearing is the perception of sound in the brain from the vibration of air waves.
The three bones of the middle ear transmit the vibrations of moving air to the oval window on the cochlea.