communication: hsc biology option

COMMUNICATION:HSC BIOLOGY OPTION

Visual Communication involves the eye registering changes in the immediate environment

The outer eye:

CONJUNCTIVA A thin, transparent

mucous membrane that covers the sclera (the white of the eye).

It lines the inner surfaces of the eyelids.

Tiny secretory glands in the produce tear film that lubricates and protects the eye while it moves in its socket and helps to keep it clean.

It covers and protects the surface of the cornea

CORNEATransparent front window through which light enters the eyeball.

SCLERA

The external layer of the eye continuous with the cornea.

The white of the eye.

SCLERA Tough, non elastic

tissue protects the delicate inner layers of the eye.

It helps to maintain the shape of the eyeball.

Attachment for the external muscles of the eye which enable the eyeball to move in the socket.

The inner eye:

LENS -

Biconcave disc

Refracts light rays & focuses them on the retina.

CILIARY BODY- Holds the lens in place yet allows flexible movements of the lens.Secretes the aqueous humour

IRIS Coloured part of the eye A ring of muscle with a

hole in the middle (the pupil).

Controls size of pupil & amount of light entering eye.

In dim light pupil dilates to let more light in.

In bright light the iris tightens and the pupil contracts.

RETINA The inner layer of the eye.

Contains photoreceptors for vision

Highly specialised rod & cone cells respond to light, converting light energy into nerve impulses.

Aqueous & Vitreous Humour

Transparent watery fluid

Provides nutrients for the lens & cornea.

Clear jelly-like substance

Refracts light Helps maintain the

shape of the eyeball

CHOROID The middle layer of the eye which extends into the iris

A sheet of blood vessels that carries oxygen & nutrients to the eye and remove carbon dioxide and wastes

Posteriorly it is black which prevents light in the eye from scattering.

Transfers the visual signals to the brain for processing.

OPTIC NERVE

Bibliography:

http://www.wolfeeyeclinic.com/images/cornea.jpg

http://www.geocities.com/centennial3d/labelledexterior2.jpg

http://homepage.ntlworld.com/pshinde/index_nt_files/picture_data/sclera_dot_.jpg

http://www.stlukeseye.com/popups/images/Choroid.jpghttp://jbooy.files.wordpress.com/2008/10/j01retina.jpg

http://static.howstuffworks.com/gif/adam/images/en/retina-picture-c.jpg

http://fc02.deviantart.com/fs27/f/2008/042/0/0/Iris_Eye_Macro_Stock_by_zpyder.jpg

http://www.msstrength.com/wp-content/themes/zen/images/optic_nerve.jpg