b1 the nervous system

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volountary actions and reflex actions:

"volountary actions are under the concious control of your brain, eg you decide how to react to the stimulas. Reflex actions bypass your brain to give fast and automatic respnses to a stimulas to help protect you from harm. eg knee jerk reaction and pulling your hand away from a flame."

THE PATHWAY THAT THE MESSAGE TAKES IS CALLED THE REFLEX ARC- Some Really Smelly ---- Mice Eat Rice

the eye

the IRIS controls the amount of light entering your eyes, the rays of light are refracted by your CORNEA and the LENS focuses light onto the RETINA so that the rays converge at a single point to make a clear image on the RETINA. N.i pass along the optic nerve to your brain.

Accomodation:

the lens is a clear bag of fluid surrounded by cillialary muscles- suspensory ligament attach the lens to the cilliary muscles.

when recieving objects from a near object ciliary muscles contract, suspensory ligaments relax and the lens is short/fat to refract light a lot.

common eye defects are long sight (corrected…

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