The Human Eye: Structure (Edexcel IGCSE Biology)

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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 Tip

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

Author: Lára

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.