LC BIOLOGY- The Senses

Sclera

outermost layer of the eye

Cornea

• allows light to pass through

• bends (refracts) the light and helps to focus it

Choroid

has:

• a dark layer to absorb the light to prevent reflection

• a large blood supply to nourish the eye

Ciliary Body

contains the ciliary muscle, which controls the shape of the lens

Lens

focuses light onto the retina

Iris

controls the amount of light entering the eye

Pupil

circular opening in the middle of the iris

Humours

liquids that exert an outward pressure on the eye, keeping its shape

food and oxygen diffuse across these liquids to feed the lens and cornea

Aqueous Humour

fills the chamber to the front of the lens

Vitreous Humour

fills the chamber behind the lens

Retina

houses the photoreceptors : rods and cones

Rods

are used in dim light and are responsible for night (black and white) vision

Cones

only function in good light intensity (colour vision)

Fovea

where the light is focused for the most accurate vision

Optic Nerve

carries the nerve impulses from the eye to the brain

Blind Spot

where the optic nerve leaves the retina, there are no light receptors

Hypermetropia

long-sightedness

GROMITS

corrects long-sightedness

Hearing

the sensing of waves of pressure in the air (sound) as they hit the eardrum

Pinna

picks up sound

Auditory Canal

sound is funnelled into here

Eardrum

at the end of the auditory canal

Ear Ossicles

the vibration of the eardrum is transferred across the middle ear by these bones (also known as the hammer, anvil, and stirrup)

Oval Window

connected to the stirrup

Cochlea

oval window leads into this

Auditory Nerve

nerve messages are carried along this nerve, from the ear to the brain, for interpretation

Round Window

vibrations pass along the cochlea, and are lost back into the middle ear here

Semi Circular Canals

• found in the inner ear

• fluid-filled structures that contain receptors, that respond to movement or the position of the head

• used to keep your posture and balance

Eustachian Tube

relieves pressure in the ear