THE SENSES EYES & EARS Biology 12 Sections 9.5 & 9.6

SCLERA Outer covering of the eye that supports and protects the eye’s inner layers; usually referred to as the white of the eye.

CORNEA Transparent part of the sclera that protects the eye and refracts light toward the pupil of the eye.

AQUEOUS HUMOUR Watery liquid that protects the lens of the eye and supplies the cornea with nutrients.

CHOROID LAYER Middle layer of tissue in the eye that contains blood vessels and dark pigments that absorb light to stop reflection.

IRIS Opaque disk of tissue surrounding the pupil that regulates amount of light entering the eye.

RETINA Innermost layer of tissue at the back of the eye containing photoreceptors.

RODS Photoreceptors that operate in dim light to detect light in black and white.

CONES Photoreceptors that operate in bright light to identify colour.

FOVEA CENTRALIS Area at the centre of the retina where cones are most dense and vision is sharpest.

GLAUCOMA Disorder of the eye caused by build up of fluid in the chamber anterior to the lens.

CATARACT Condition that occurs when the lens or cornea becomes opaque, preventing light from passing through.

ASTIGMATISM Vision defect caused by abnormal curvature of the surface of the lens or cornea.

NEARSIGHTEDNESS A condition that occurs when the image is focused in front of the retina.

FARSIGHTEDNESS A condition that results when the image is focused behind the retina.

ANATOMY REVIEW    

PINNA Outer part of the ear that acts like a funnel, taking sound from a large area and channelling it into a small canal.

AUDITORY CANAL Carries sound waves to the eardrum.

TYMPANIC MEMBRANE Thin layer of tissue, also known as the eardrum.

OSSICLES Tiny bones that amplify and carry sound in the middle ear. They include the malleus, incus, and stapes.

OVAL WINDOW Oval-shaped hole in the vestibule of the inner ear, covered by a thin layer of tissue.

EUSTACHIAN TUBE Air-filled tube of the middle ear that equalizes pressure between the external and internal ear.

VESTIBULE Chamber found at the base of the semicircular canals that provides information about static equilibrium.

SEMICIRCULAR CANALS Fluid-filled structures within the inner ear that provide information about dynamic equilibrium.

COCHLEA Coiled structure of the inner ear that responds to various sound waves and converts them into nerve impulses.

ORGAN OF CORTI Primary sound receptor in the cochlea.

BASILAR MEMBRANE Anchors the receptor hair cells in the organ of Corti.

HOW THE EAR WORKS        