human eye

Photoreceptors

Receptors (rods and cones) in the eyes that respond to light stimuli

Optic nerve

Nerve that transmits impulses from the eye to the occipital lobe of the brain

Conjunctiva

Delicate mucous membrane that covers the front of the eye and contains pain receptors

Sclera

White connective tissue layer of the eye

Cornea

Front transparent part of the sclera that refracts light as it enters the eye

Choroid

Dark, pigmented layer of the eye that contains many blood vessels

Iris

Circular and coloured continuation of the choroid in the eye that adjusts the size of the pupil to determine how much light can enter the eye

Pupil

The hole in the middle of the iris that allows light the pass through onto the retina

Retina

Inner, light-sensitive layer of the eye that contains the photoreceptors

Rods

Photoreceptors that are respond to light and dark (low-intensity light) and provide night vision and peripheral vision

Cones

Photoreceptors that respond to colour (bright-intensity light) and provide sharp, clear vision

Blind spot

Area on the retina where the optic nerve leaves the eye and no photoreceptors are found

Yellow spot

Area of the eye where mostly cones occur and provides the sharpest, clearest vision

Lens

Biconvex, flexible and transparent structure that can alter its shape to refract light rays

Eye Accommodation

Active adaptations of the lens to focus a nearby image on the retina

Binocular vision / Stereoscopic vision

The overlapping of visual fields that allow for better depth-perception and the judgement of distance

Near-sightedness / Short-sightedness

Condition where images far from the eye cannot be seen clearly due to an elongated eyeball or a very convex (round) lens

Far-sightedness / Long-sightedness

Condition where images close to the eye cannot be seen clearly due to a shortened eyeball or very flat lens

Astigmatism

Condition of the eye where the lens or cornea is irregularly shaped causing blurred vision

Cataract

A dark, cloudy area on the lens caused by the clumping of lens proteins that prevents light from passing through onto the cornea

Vestibular apparatus

Structure in the ear comprised of the semicircular canals, sacculus and utriculuc which helps to maintain balance

Cochlea

Structure in the ear which receives sound stimuli and helps us to hear

Ossicles

Small bones in the middle ear that vibrate to transmit and enhance sound waves as they pass to the inner ear

Pinna

The earlobe that catches up sound waves from the environment

Tympanum

The ear drum which vibrates to transmit sound waves from the external auditory canal into the middle ear

Eustachian tube

A thin tube that connects the middle ear to the throat and helps to maintain pressure on either side of the ear drum

Oval window

A membrane in the middle ear that vibrate to carry sound waves into the inner ear

Round window

Membrane in the inner ear that absorbs excess sound waves to prevent echoes

Organ of Corti

The receptor for hearing in the ear.

Auditory nerve

Nerve that collects information from the cochlea and vestibular apparatus in the ear and conducts the impulses to different parts of the brain

Utriculus and sacculus

Structures in the vestibular apparatus that contain the maculae to register the head's position in relation to gravity

Maculae

Equilibrium receptor in the sacculus and utriculus that responds to the head's position in relation to gravity

Semicircular canals

Three canals at right angles to one another that contain swollen areas called ampulla where receptor cells called cristae register the movement of the head

Cristae

Receptor cells in the ampulla of the eat that register the movements of the head

Maculae and Cristae

Equilibrium and balance receptors in the ear