Regulation, Intergration and control in anatomy and physiology

chapter 6

what does the eye do?

captures and processes light, allowing us to experience colour, shapes, and movements

whats in the outer layer of the eye

the cornea and sclera

the cornea

transparent dome shape front surface of the eye

what does the cornea do?

helps focus incoming light onto the inner of the eye

the sclera

white, tough and fibrous outer covering of the eye surface

what does the sclera do?

structured support and attachment points for the muscles to control eye movement

what is the middle layer of the eye also called

Uvea

whats in the middle layer of the eye

the iris, pupil, ciliary body, choroid

the iris

coloured part of eye surrounding pupil

what does the iris do?

muscles controlling the size of pupil regulating light entering

the pupil

dark opening in the center of eye,

what does the pupil do?

adjusts size to control amount of light reaching inner structure

the ciliary body

ring shaped structure behind the iris

what does the ciliary body do?

contains ciliary muscles that control the shape of lens, allowing for focus on objects at varying distance

where is the choroid

vascular layer between sclera and retina

what does the choroid do?

supplys nurtients and oxygen to retina and helps to absorb excess light to prevent reflection and glare

whats the inner layer of the eye

Retina

whats in the inner layer of the eye

the retina, macula, optic nerve

the retina

thin, delicate layer of tissue lining the back of the eye

what does the retina do?

contains millions of special cells, photoreceptors convert light into electrical signals

what are the two photoreceptors

rods and cones

what are rod photoreceptors

allow us to see in dim lighting conditions and peripheral vision

what are cone photoreceptors

allow us to see in bright light and colour vision and visual acuity

the macula

small, specialized region in centre of retina

what does the macula do?

contains high density of cones, responsible for central vision and fine details

the optic nerve

bundle of over a million nerve fibres

what does the optic nerve do

transmit visual info from retina to brain for processing and interperating

what are the auxiliary structures contributing to overall function of the eye

the lens, aqueous and vitreous humors

the lens

flexible structure located behind iris

what does the len do?

focus light onto retina by changing shape with ciliary muscles

aqueous humor

clear fluid fills front chamber of eye

vitreous humor

gel like substance fills larger space behind the lens

what does the aqueous and vitreous humors do?

maintain shape and provide nutrients to lens and retina

what is the process of how light enters an eye

light hits cornea, through pupils, widened or narrowed by iris due to various light conditions, then to lens, changes shape to focus onto retina so we can focus on objects at different distances

phototransduction

converts light energy into electrical signals that can be processed by the brain

how does the electrical signals visually get processed?

optic nerve carrys signal to visual processing centers in occipital lobe.

optic chiasma

left and right optic nerves meet and partial nerve fibers cross over to the opposite side of the brain

decussation

the place the nerve fibres cross in the optic chiasma

visual cortex

assembles info from eyes interperating, shapes colours, depth and motion