The nervous system

• the nervous system allows to react to what is going on around us
• Nervous system is made up of nuerons which go to all parts of the body
• sensory receptors are a group of cells that detect a change in environment ( a stimulus)
• A change enviornment is a stimulus
• Receptors in eyes detect light
• Skin receptors detect touch and temp change
• Once a stimulus is detected it is CONVERTED into a nervous impulse and sent along CNS
• once it is sent along CNS, CNS decides what to do about stimulus and tells something to do it
• CNS sends information on what to do with impulse along a motor neurone to the effector
• The effector responds to the stimulus and produces a response
• The time that is taken to respond to a stimuli is a reaction
• All nuerons have a cell body and a nucleus
• dendrites and dendrons are extensions of cell body that connect to other nueronea
• Dendrites and dendrons carry nerve impulses to cell body
• Axons carry nerve impulses away from cell body
• Some extensions like axons and dendrons and dendrites are coated in myelin sheath
• myelin sheath acts as an electrical insulator which speeds up electrical impulse speed
• One long neurone is faster than many short nuerones because it can carry more information
• Motor nuerone has a long axon and many short dendrites
• A long axon in motor neurone carries impulse from cell body to effector nuerones
• short dendrites in motor neurone carry impulse from CNS to cell body
• impulse goes from SENSORY to RELAY to MOTOR TO EFFECTOR
• sensory nuerone has a long dendron (impulse from receptor to cell body)short axon carry impulse from cell body to CNS
• Relay neurone have short dendrites that carry nerve impulse from sensory nuerone to cell body
• In relay and Axon carries impluse from cell body to motor nuerone
• sensory nuerone pick impulse up from receptor organs and sends to CNS
• impulse is taken from CNS to nuerone to motor neurones by relay
• motor takes impulse from CNS to effectors