Reflex Action
- Created by: Sophia Dowden
- Created on: 30-05-16 15:59
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- Reflex Action
- Rapid involuntary (brain not involved) and protective (function) from the stimulus
- e.g. withdrawal reflex, light reflex, stretch reflex, whisker reflex, triceps surae reflex, stepping reflex.
- The reflex arc is related to nerve pathways and nerve impulses are passed to the brain/from the brain via ascending and descending tracts.
- e.g. withdrawal reflex, light reflex, stretch reflex, whisker reflex, triceps surae reflex, stepping reflex.
- What is the difference between white and grey matter?
- Grey matter contains the cell bodies/nuclei of the neurons whilst the white matter is mainly axons and made up of myelin.
- With any reflex action there is also a pathway for impulses to be sent to the brain via ascending nerve fibers that originate in the synapse in the grey matter of the spinal cord.
- The brain may stire this inforation or it may relate the information with sense data, say, he eyes.
- As a result of recieving extra information, impulses may be sent form the brain to modify the rsponse.
- Sometimes the response is over-ridden by the brain to modify the response.
- Soetimes the response is over-ridden by the brain along inhibitory nerve fires.
- Sometimes the response is over-ridden by the brain to modify the response.
- As a result of recieving extra information, impulses may be sent form the brain to modify the rsponse.
- The brain may stire this inforation or it may relate the information with sense data, say, he eyes.
- Nerve nets in simple organsms
- Simple organisms do not posses many recptors and effectors.
- The sense reptors respond to a limited number of stimuli and the number of effectors is small.
- An example of this is the hydra-coelenterates (jellyfish)
- The sense reptors respond to a limited number of stimuli and the number of effectors is small.
- The hydra does not have a recognisable brain or true muscles.
- It has a simple nervous system known as a nerve net.
- Nerve nets connect sensory receptors and touch sensitive cells locatd in the body walls and tentacles.
- The nerve nets consists of simple nerve cells with shirt extensions joined to each other and branching in a number of different directions
- This means that the transmission of the nerve impulse is slow
- The nerve nets consists of simple nerve cells with shirt extensions joined to each other and branching in a number of different directions
- Nerve nets connect sensory receptors and touch sensitive cells locatd in the body walls and tentacles.
- It has a simple nervous system known as a nerve net.
- Direction of impulse
- Impulse can transmit in BOTH directions
- Speed transmission = slow
- Description = short and branched
- Non - myelinated
- Simple organisms do not posses many recptors and effectors.
- Nerve nets in complex nervous system
- Direction of impulse
- Impulse is transmitted in ONE direction
- Speed of trasmission
- Fast
- Description
- Long and unbranched
- Myelinated
- Direction of impulse
- Rapid involuntary (brain not involved) and protective (function) from the stimulus
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