The Nervous System
- Created by: Covetablerat12
- Created on: 15-05-16 15:50
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- The Nervous System
- Nerve Cells
- Bundles of neurones form nerves and these nerves form the nervous system: The central nervous system consists of the brain and spinal chord. The peripheral nervous system consists of nerves connecting the sense organs with the CNS.
- Nerves consist of different types of neurone which send impulses in particular directions:
- Sensory Neurones send impulses from receptors in the sense organs to the CNS
- Motor Neurones send impulses from the CNS to muscles and glands
- A neurone is a nerve cell that consists of a cell body with thin fibres stretching out from it. These fibres carry electrical impulses.
- Receptors
- Receptors in the sensory neurone fibres detect stimuli and convert them into electrical impulses; these are sent along neurones to muscles and glands.
- Different types of receptor detect different types of stimuli: Photoreceptors detect light; thermoreceptors detect body temperature changes.
- Some types of receptor can be found all over the body. ie. the thermorecep-tors are found across the skin.
- Other types of receptor are concentrated in sense organs. ie. The photoreceptors form a layer of cells in the eye called the retina.
- Sensitivity to touch depends on the force bearing down on that area and the number of touch receptors in that area.
- Dendrons and Axons
- Sensory and Motor Neurones have similarities and differences
- They both have a cell body and fine branches called dendrites
- The fibre that carries the impulses from the cell body to the dendrites is called the axon. Motor Neurones have very long axons, whereas sensory neurones have short axons.
- The fibre that carries impulses to the cell body is called the dendron.
- Sensory and Motor Neurones have similarities and differences
- Nerve Cells
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