The Human Eye: Structure (Edexcel IGCSE Biology)

Revision Note

The Human Eye: Structure

  • The eye is a highly specialised sense organ containing receptor cells that allow us to detect the stimulus of light

  • The retina of the eye contains two types of receptor cells:

    • Receptor cells that are sensitive to light, known as rods, and receptor cells that can detect colour, known as cones

eye-structure

The eye is a sense organ that contains light receptor cells

The structures of the eye 

  • Cornea - transparent lens that refracts light as it enters the eye

  • Iris - controls how much light enters the pupil

  • Lens - transparent disc that can change shape to focus light onto the retina

  • Retina - contains light receptor cells – rods (detect light intensity) and cones (detect colour)

  • Optic nerve - sensory neuron that carries impulses between the eye and the brain

  • Pupil - hole that allows light to enter the eye

  • Conjunctiva - a clear membrane that covers the white of the eye and the inside of the eyelids; it lubricates the eye and provides protection from external irritants

  • Ciliary muscle - a ring of muscle that contracts and relaxes to change the shape of the lens

  • Suspensory ligaments - ligaments that connect the ciliary muscle to the lens

  • Sclera - the strong outer wall of the eyeball that helps to keep the eye in shape and provides a place of attachment for the muscles that move the eye

  • Fovea - a region of the retina with the highest density of cones (colour detecting cells) where the eye sees particularly good detail

  • Blind spot - the point at which the optic nerve leaves the eye, where there are no receptor cells

Examiner Tips and Tricks

Make sure you can identify the structures of the eye on a diagram because diagrams with labels are a very common form of exam question for this topic. 


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Lára Marie McIvor

Author: Lára Marie McIvor

Expertise: Biology Lead

Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.