Biology the nervous system

sense organs detect stmuli
1. stimuli is a change in your environment
5 different sense organs-ears,eyes,nose,tonge&skin
1. all contain diff receptors-are groups of cells which are sensitive to a stimulus. they change stimulus energy into electrical impulses.
2. a stimulus could be light,sound,touch,pressure,pain,chemical or a change in position or temperature.
5 sense organs&receptors
1. eyes-light receptors-sensitive to light&cells have nucleus,cytoplasm&cell membrane(like most animal cells)
2. ears-sound receptors-sensitive to sound-also balance receptors to changes in position
3. nose-smell receptors-sensitive to chemical stimuli
4. tounge-taste receptors-sensitive to bitter,sour,salt&sweet&savoury things-chemical stimulus
5. skin-sensitive to touch,pressure,pain and temp change
sensory neurones-nerve cells carry signals as electrical impulses from the recpeptors in the sense organs to central nervous system
Relay neurone-nerve cells carry signals from sensory Neurones to motor neurones
motor neurones-nerve cells carry signals from central nervous system to effector muscles or glands
Effectors
1. respond in diff ways. muscles contract in response to a nervous impulse, whereas glands secrete hormones
Central Nervous System(CNS)
1. coordinates a response
2. all info from sense organs is sent&where reflexes &actions are coordinated.
3. consists of brain&spinal chord only.
neurones(nerve cells) transmit info(as electrical impulses)very quickly to&from CNS instructions from CNS are sent to the effectors(muscles&glands) which respond accordinly.

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Biology the nervous system

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