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Coordination and control - The nervous system - OCR GatewayHow the eye works – Higher

The nervous system allows us to react to our surroundings very quickly and to coordinate our behavior. It comprises millions of neurones and electrical impulses pass along them very quickly.

Part of Biology (Single Science)Organism level systems

How the eye works – Higher

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, this allows the light rays to refract (bend) more strongly.

To focus on a distant object – the lens is pulled thin, this allows the light rays to refract slightly.

Position of objectCiliary musclesSuspensory ligamentsMuscle tension on lensLens shapeRefraction of light rays
NearContractSlacken/loosenLowFat/thickerLight is refracted strongly
DistantRelaxStretched/tightenHighThinLight is only refracted slightly
Position of objectNear
Ciliary musclesContract
Suspensory ligamentsSlacken/loosen
Muscle tension on lensLow
Lens shapeFat/thicker
Refraction of light raysLight is refracted strongly
Position of objectDistant
Ciliary musclesRelax
Suspensory ligamentsStretched/tighten
Muscle tension on lensHigh
Lens shapeThin
Refraction of light raysLight is only refracted slightly
Diagram showing how an image focuses at the retina
Figure caption,
The lens changes shape to focus on near and distant objects