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Sensitivity and the nervous system (The eye (eye, Conjunctiva = mucous…
Sensitivity and the nervous system
Brian & Central Nervous System
Cerebrum = controls memory, personality, and conscious thought
Cerebellum controls balance and co-ordination and conscious movement
Medulla = controls heart rate and breathing rate
Hypothalamus = regulating centre for temperature and water balance
Central nervous system
consists of the brain and spinal cord and is linked to sense organs by nerves
Nerve impulses
Stimulation of receptors in the sense organs sends electrical impulses along nerves into and out of the central nervous system
Receptor in the skin detects a stimulus (the change in temperature).
Sensory neurone sends impulses to relay neurone.
Motor neurone sends impulses to effector.
Effector produces a response (muscle contracts to move hand away).
Response Pathway
Stimulus = A change in our environment which is detected by a receptor
Receptor = Converts one form of energy into electrical. Mostly, found inside our sense organs
Coordinator = All messages must be sent to the Central Nervous System
Effector = Either a muscle or gland (releasing enzymes or hormones or saliva)
Response = Either a movement or release of chemicals
Synapse
Information crosses the gap rather than using electrical impulses.
The eye
Conjunctiva = mucous membrane which covers the front of the sclera
Cornea = The outer coating at the front of the eyeball and covers the iris and pupil. Focuses light onto the retina
Iris = coloured circle surrounding the pupil. Changes the size of the pupil and allows different amounts of light to enter the eye.
Lens = Bends light rays so that they form a clear image at the back of the eye on the retina. It can change shape, getting fatter to focus close objects and thinner for distant objects.
Pupil = hole in the centre of the iris which allows light to enter the retina.
Retina = Light - sensitive area at the back of the eye. Rays of light enter the eye and are focused on the retina by he cornea and lens. It produces an image which is sent along the optic nerve for the brain to interperate.
Sclera = white part of the eye
