- where the sclera meets the cornea - its a drainage point for the aqueous humour

- transparent anterior part of the eye - avascular - outer surface is a layer of squamous epithelium - function is to focus light on the retina

- dark coloured lining at the back of the eye - prevents light rays escaping

- 2 layers of smooth muscle - contains a pigment called melanin - eye colour - controls light into the eye - circular contraction = smaller pupil - radial contraction = larger pupil

- photoreceptor cells - sensitive to low light levels, providing black and white night vision

- photoreceptor cells - sensitive to bright light and provide colour day vision

Special senses Flashcards by Chloe Reynolds

what are some characteristics of sensory receptors?

lie outside of the central nervous system
feed information to the brain
creates a response

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what are some characteristics of the eyes?

receptor organ for sight
lie within the deep bony orbit of the skull

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what provides cushioning for the eye?

periorbital fat

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what are the three main parts of the eye?

eyeball
extrinsic
eyelids

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what are the muscles in the eye useful for?

Movement and suspension

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what is the orbit comprised of?

comprised of the frontal bone, lacrimal bone, and zygomatic arch

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what is eye position relative to?

environment
habits
feeding methods

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what are some characteristics of a predator’s eye position?

forward set eyes
large central area
binocular/stereoscopic vision
greater depth perception

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what are some characteristics of a prey’s eye position?

laterally placed eyes
wider range of vision
narrow 3D vision

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what are the three layers of the eye?

sclera/cornea (outermost)
uvea (middle)
retina (inner)

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what do the three layers of the eye form?

a sheath around a liquid-gelantinous centre

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what is the limbus?

where the sclera meets the cornea
its a drainage point for the aqueous humour

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what is the cornea?

transparent anterior part of the eye
avascular
outer surface is a layer of squamous epithelium
function is to focus light on the retina

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what does the uvea contain?

choroid
ciliary body
iris
tapetum lucidum

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what is the choroid?

dark coloured lining at the back of the eye
prevents light rays escaping

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what is the ciliary body?

structure projecting towards the centre of the eye
secretes aqueous humour
ciliary muscles control the shape and thickness of the lens

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what is the iris?

2 layers of smooth muscle
contains a pigment called melanin - eye colour
controls light into the eye
circular contraction = smaller pupil
radial contraction = larger pupil

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what is the tapetum lucidum?

light reflecting layer of cells on inner choroid surface

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what does the retina contain?

light sensitive cells and is connected to the brain via the optic nerve

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what are the three layers of sensory cells in the retina?

photoreceptor layer
bipolar layer
ganglion layer

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what are rods?

photoreceptor cells
sensitive to low light levels, providing black and white night vision

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what are cones?

photoreceptor cells
sensitive to bright light and provide colour day vision

what do bipolar nerve cells do?

gather information from the rods and cones and transmit it to the next layer

what are ganglion cells?

cells travel across the surface of the retina towards the optic disc where they form the optic nerve
blind spot where the optic nerve leaves the retina

what is the lens?

- between the cornea and the retina - transparent biconvex disc - function is to change shape and focus. rays of light onto the retina to focus on an object which may be close or far away

what two chambers does the iris divide into?

- anterior chamber (iris and cornea) - posterior chamber (iris and lens)

what is the final chamber?

vitreous chamber - between the lens and retina - contains vitreous humour

what does pressure in the anterior chamber cause?

glaucoma

what are some accessory structures in the eye (adnexa)?

- eyelids - lacrimal apparatus - ocular muscles

how are the upper and lower eyelid joined?

at the medial canthus and lateral canthus

what is the function of the eyelids?

to protect the globe from damage, uniform, tear distribution and protection during sleep

what are the harderian glands?

lie underneath the third eyelid and contribute to lubrication

what does the enlargement of the harderian glands cause?

cherry eye

what is the third eyelid called?

nictitating membrane

what glands are along the margin of the eyelid?

meibomian glands and tarsal glands/plates

what does the lacrimal gland produce?

secretion known as tears which contain sodium chloride and bicarbonate

what is the function of tears?

moisten cornea and conjunctiva, remove dust and debris, and contains lysozyme to destroy bacteria

what is the journey of light reception?

light cornea iris retina light receptor cells optic nerve mid brain correct cerebral cortex

what are the three parts of the ear?

EXTERNAL ear MIDDLE ear INNER ear

what are some characteristics of the external ear?

- pinna - expression and communication - formed from a sheet of elastic cartilage

what are the 2 parts of the external ear?

- vertical canal - horizontal portion

what are some characteristics of the middle ear?

- consists of tympanic cavity (contains ossicles) and tympanic membrane (ear drum) and auditory ossicles

what is the function of the tympanic membrane?

to convey the vibrations caused by sound waves from external to ossicles

what are the auditory ossicles?

malleus (hammer) incus (anvil) stapes (stirrup) - function is to transmit soundwaves to inner ear

what are the two parts of the inner ear?

- bony labyrinth - cochlear - membranous labyrinth - vestibular

what is perilymph?

fluid that surrounds and separates

what is endolymph?

fluid flowing in tubes

what is the cochlear portion?

- wound spirally like a snail - organ reacts to different sound wave frequencies - sends message to cochlear branch of CN8 to brain

what is the vestibular portion?

comprises of three semi-circular canals - utricle - ampulla - saccule

what are some characteristics of the semicircular canals?

- lie in 3 planes at right angles - contains hair and crystals that move as body moves = balance - filled with endolymph

what are some characteristics of taste?

- gustation - particles must be in solution - taste buds on moist mucosa - taste bud = receptor organ -tongue associated with papillae

what do taste buds contain?

- gustatory cells - supporting cells - hair like processes

what are some characteristics of smell?

- olfaction - receptor in nasal mucous membranes covering turbinates - vomeronasal response allows transfer of pheromones and other scents into vomeronasal organ at roof of mouth