Biology 30 - Unit 1 Booklet 2: The Senses (Terms)

Sensory Receptors

Parts of the body that convert one energy form about the external environment into nerve impulses and relay it to the CNS

Sensory Adaptation

When an individual has adjusted to a change in the environment, making neurons cease to fire even though stimulus is still present

Pinna

The flaps of the ear made of cartilage that funnel sound to the auditory canal

Auditory Canal

The hole in the outer ear that funnels sound to the eardrum containing sweat glands that produce ear wax

Tympanic Membrane/Tympanum

The air-filled membrane separating the outer ear from the middle ear that vibrates in response to sound waves

Ossicles

Three small bones that amplify and pass sound from the eardrum to the oval window

Oval Window

The opening between the middle and inner ear that amplifies sound

Eustachian Tube

A tube connected to the throat that allows for air pressure equalization in the ear

Semicircular Canals

Three fluid-filled rings that are responsible for dynamic equilibrium balance through using movement of fluid to identify body movement

Vestibule

The cavity connected to the oval window that is responsible for static equilibrum balance by using the utricle and saccule to establish head position

Cochlea

The snail-shaped part of the inner ear containing two rows of hair cells that convert vibrations into nerve impulses

Sclera

The outermost white layer of the eye that maintains the eye’s shape and acts as protection

Cornea

The clear window covering the sclera that acts as a window to bend light towards the pupil

Aqueous Humour

Transparent fluid behind cornea that provides nutrients to the eye

Choroid Layer

The middle layer of the eye that prevents light from scattering and containing blood vessels

Iris

Thin circular muscle towards the front of the choroid layer that allows light into the eye by controlling the size of the pupil

Pupil

The hole in the center of the iris where light enters the eye

Lens

Clear part behind the iris that focuses images onto the retina

Cilliary Muscles

Mucles attached to ligaments in the lens that alter the shape of the lens

Vitreous Humour

Cloudy, jelly-like material that maintains the shape of the eyeball and allows light to transmit to retina

Retina

Innermost layer of the eye that contains rods and cones

Rods

Light-sensitive cells found in the retina that respond to low-intensity light (black and white)

Cones

Light-sensitive cells found in the retina that respond to high-intensity light (colour)

Fovea Centralis

The focal point in the center of the retina that is packed with the most cones

Blind Spot

The area in which the optic nerve comes in contact with the retina where no rods or cones are present

Positive Afterimage

Being able to see an image after looking into a bright light and then closing your eyes because the image is “burned” into the retina

Negative Afterimage

Seeing a colour reversal of an image after the eye is exposed to bright coloured light for an extended time caused by fatigue of cones responsible for a particular colour while others continue to fire

Cataract

When the lens becomes opqaue, preventing light from passing through

Glaucoma

Buildup of aqueous humour in anterior chamber of eye caused from a blocked drainage duct, resulting in vision loss from death of retinal cells due to pressure

Astigmatism

Lens or cornea is irregularly shaped

Colourblindness

An inherited condition where one lacks certain cones

Myopia

Near-sightedness that occurs when the eyeball is too long, causing rays from distant objects to focus in front of the retina and appear blurry

Hyperopia

When the eyeball is too short, causing rays from nearby objects to focus behind the retina and appear blurry