Summary The eye and the ear Gr 11 & G12 life sciences notes
89 views 4 purchases
Course
Life Sciences
Institution
12th Grade
Detailed notes of the eye and the ear, part of the nervous system section.
Including:
The structure of the eye
The functioning of the eyeball
Visual defects
The structure of the ear
The functioning of the ear
Hearing defects
, Human eye
Structure of the eye
Eyeballs in bony skull sockets.
Bone, eyelids & eyelashes protect eyes from mechanical injury.
Muscles attached to eyeball keep it in socket & to move.
Glands secrete tears & oily substance onto surface prevent drying out.
Made of three layers: sclera, choroid & retina (St Catherine’s rules)
Sclera
Outer layer, tough inelastic tissue.
Maintains shape of eyeball & is point where eye muscles attach.
Front part of sclera called cornea, transparent & allows light pass into eye.
Conjunctiva is thin membrane covers front of eyeball, contains sensory nerve endings
protect eye by detecting presence of foreign object.
Choroid
Aka middle vascular layer, dark in colour.
Contains blood vessels, brings 02 & nutrients to cells of retina. Dark colour absorbs light rays.
Prevents refraction of light inside eyeball, prevents images blurring.
Front part of choroid forms iris, coloured part.
Iris surrounds hole called pupil. Light enters eye through pupil.
Retina
Inner layer, made of photoreceptors, convert light to nerve impulses. Called rods & cones.
Rods active in dim light & allow see b&w images, contain pigment rhodopsin.
Cones active in bright light & allow see colour, pigment called iodopsin.
Fovea/yellow spot, area on retina contains only cones, area of sharp vision.
Each type of cones detects different colour, person colour blind if 1/more cones types absent.
Bipolar neurons travel from photoreceptors & leave eyeball, make blind spot.
Blood vessels enter & leave at this point. Optic nerve carries nerve impulses to visual cortex in
cerebellum where interpreted as images, allows us to see.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller erinswanepoel. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $4.46. You're not tied to anything after your purchase.
