a) What is a reflex action? b) Outline the activities that occur in the body when one touches a hot object.

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a)  What  is  a  reflex  action?
 Rapid  and  automatic;  response  to  a  particular  stimulus;  2  mks

 b)  Outline  the  activities  that  occur  in  the  body  when  one  touches  a  hot  object.
 When  the  hot  object  is  touched,  the  pain  receptors;  in  the  skin  of  the  finger  are  stimulated; nerve  impulses  are  initiated  and  transmitted  through  the  sensory  neurone;  to  the  grey  matter; of  the  spinal  cord  to  the  brain;  for  interpretation;  the  impulses  are  then  transmitted  through the  relay  neurone;  via  a  synapse;  the  impulses  from  the  relay  neurone  are  transmitted  via  the motor  neurone;  through  another  synapse;  to  the  effector;  which  are  the  biceps  muscles  of  the upper  arm;  making  the  muscles  to  contract;  straightening  the  arm;  and  the  arm  is  withdrawn from  the  hot  object;  Max.  18  mks 

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