Biology: hearing and equilibrium

Hearing

Response to vibrating air molecules.

Equilibrium

Sense of motion, body orientation, and balance.

Location of Hearing and Equilibrium

Both senses reside in the inner ear.

Scala Vestibuli

Superior, perilymph-filled chamber of the cochlea.

Scala Tympani

Inferior, perilymph-filled chamber of the cochlea.

Scala Media

Middle chamber of the cochlea filled with endolymph.

Organ of Corti

Acoustic organ that converts vibrations into nerve impulses.

Loudness

Perception of the amplitude of vibration.

Pitch

Sense of high or low sound determined by vibration frequency.

Conductive Deafness

Hearing loss caused by conditions interfering with vibration transmission to the inner ear.

Sensorineural Deafness

Hearing loss caused by the death of hair cells or nervous system elements.

Vision

Perception of objects by means of light they emit or reflect.

Human Vision Wavelengths

Ranges from 400 to 700 nm.

Conjunctiva

Transparent mucous membrane lining eyelids and the eyeball's anterior surface.

Lacrimal Gland

Tear duct.

Sclera

The white of the eye; part of the outer fibrous layer.

Cornea

Transparent region of modified sclera in front of the eye that admits light.

Choroid

Highly vascular, deeply pigmented layer behind the retina.

Ciliary Body

Muscular ring around the lens that supports it and secretes aqueous humor.

Iris

Colored diaphragm controlling the size of the pupil.

Fovea Centralis

Center of the macula providing finely detailed images due to packed receptor cells.

Optic Disc

Region with no receptor cells that acts as the blind spot.

Parasympathetic Pupil Response

Narrows the pupil.

Sympathetic Pupil Response

Widens the pupil.

Photopupillary Reflex

Automatic pupillary constriction in response to light.

Rod Cells

Photoreceptors responsible for night vision.

Cone Cells

Photoreceptors responsible for color or day vision.

Dark Current

Phenomenon where rods steadily release glutamate in the dark.

Bipolar Cells

First-order neurons that synapse with rods/cones and ganglion cells.

Ganglion Cells

Second-order neurons whose axons form the optic nerve.