How the eye works

• The nervous system enables humans to react to their surroundings and coordinate their behavior
• The nervous system comprises millions of neurones and uses electrical impulses to communicate quickly
• Homeostasis is the process of maintaining a stable internal environment
• Reflex arc is an automatic response to a stimulus
• The brain is responsible for processing information and controlling body functions
• How the eye works:

  • Accommodation is the process of changing the shape of the lens to focus on near or distant objects
  • To focus on a near object, the lens becomes thicker, allowing light rays to refract more strongly
  • To focus on a distant object, the lens is pulled thin, allowing light rays to refract slightly
• Common defects of the eye and how they're overcome:

  • Near vision: Ciliary muscles contract, suspensory ligaments slacken, lens becomes fat/thicker, light is refracted strongly
  • Distant vision: Ciliary muscles relax, suspensory ligaments stretch/tighten, lens becomes thin, light is only refracted slightly