Reflexes
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REFLEXES
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Transcript of Reflexes
- 1. REFLEXES
2. Actions performed automatically in response to a stimulus without conscious thought or decision are calledreflex actionsorreflexes.
- Simple reflex actions are handled by thespinal cordwithout involvement of the brain.
- Other reflexes are carried out in various relay centers in thelower brain or brainstem , butno conscious thoughtis involved.
- Reflex actions carried out by the spinal cord occur automatically, but at the same time as the reflex occurs, sometimes a signal is sent to the brain by a connecting interneuron.When this happens, a stimulus is processed by the spinal cord as an arc and a response is sent back to the periphery, but a signal is also sent to the brain for interpretation and additionalreaction .
3. Examples of each of these are: a. Knee jerk response (simple/spinal cord only) 4. b. Sneezing one of the reflex centers in the medulla (involvesbrainstem activity only) 5. c. Hand on a hot stove a simple reflex pulls the hand away (spinal cord arc only, no brain involvement) followed by a reaction due to an interneuron connection to the brain from the spinal cord. 6. **optional
- The systems described above represent the simplest units of the nervous system and are calledreflex arcs .There are 5 parts to these:
- 1.Sensory receptor(s)is/are stimulated.
- Sensory neuron(s)send(s) message to the spinal cord.
- ** Interneuron(s)in CNS transmit the message to one or more motor neurons.
- Motor neuronstransmit the message to the effector.
- Effector(muscle) is stimulated.