KCSE 2016 Q7 USING A RELEVANT EXAMPLE IN EACH CASE, DESCRIBE SIMPLE AND CONDITIONED REFLEX ACTIONS. (20 MARKS)

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Simple reflex action e.g. withdrawal of finger from a sharp object/ hot object;
  • Its an automatic response to a specific stimulus; when the finger touches sharp object/ hot object, the pain receptors/ thermo-receptors in the skin are stimulants; and trigger off a nerve impulse; the nerve impulse is transmitted via the senses neurone; to the grey matter of the spinal cord/ CNS/ brain; 
  • The impulse is then transmitted via synapse; to the relay neurone; and then through another synapse; to the motor neurone; the impulse is then transmitted to the effectormuscles in the  hand; [acc - Efferent neurone for motor neurone & Afferent neurone for sensory neurone, Intermediate/ associative/ connector/internuncial neurone - for relay].
  • The effector muscles/ biceps contract; and the finger is withdrawn from the hot object/ sharp  object; 
Conditioned reflex action - salivation in a dog/ human being (ace. any other relevant  example) student in response to sound; 
  • It is an automatic response evoked from an animal by unrelated stimulus; substituted for the one which normally elicits the response; 
  • It develops from a past experience; and involves modification of behaviour/involves learning; 
  • It weakens with time; and must be reinforced by repeating the related stimulus; 
  • The dog/ student salivates when the bell (for meals) rings; because they have learnt to associate the ringing of the bell at meal time with food; every time it rings (accept use of other relevant examples) they are offered food.

 20 MARKS

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