Published in Zoology
Monday, 29 May 2017 23:19

The voluntary activities that occur with out knowing or that occur involuntarily without the intervention of the centres of brain are called refiex actions.
Reflex actions are useful to animal because they bring about quick action in response to a stimulus. Many reflex action (spinal reflexes) relieve the brain from unnecessory work by taking care of minor activities and avoid harmful delay by not referring the stimuli to the higher centres of brain.
The flow of nerve impulse along a specific nerve pathway is called reflex arc. The path of nerve impulse in a reflex action is called reflex arc. The impulses can flow only in a single direction in a reflex arc are,
Sensory organ ----------> Afferent neuron -----------> Efferent neuron -----------> Muscle or gland (effector)
reflex arc thumb5

The reflexes in which the response (motor impulse) is formed in the spinal cord are called spinal reflexes. E.g. :
  1. Immediate withdrawl of a hand from hot surface.
  2. Movement of patella when it strikes aganist hard object.
  3. Removal of nail when it is pierced into the skin of leg or hand.
The reflexes in which the response is formed in the brain are called cerebral reflexes. E.g. :
  1. Sudden closure of eyes when a strong light is focussed.
  2. Oozing of saliva on seeing sweets.
Some reflexes can be evoked even immediately after birth and need no previous encounter with the stimulus exciting it. For example, the taste of food causes salivation even in a new-born baby or even thouh the baby is tasting that food for the first time. The pupil constricts even if the eye is illuminated with bright light just at birth. Such reflexes are called unconditioned or inborn reflexes.
reflex action2 thumb10
The reflex, acquired afterbirth by applying an indifferent stimulus before or along with the stimulus for an inborn reflex, is called a conditioned reflex or acquired reflex. Eg. The sight or smell of food is a conditioned stimulus for salivation.

Useful Sites

  • NCBI

    National Center for Biotechnology Information
  • LTO

    Lab Tests Online® by AACC
  • ASCP

    American Society for Clinical Pathology
  • ASM

    American Society for Microbiology
  • The Medical Library®

    Project of

Connect With Us

Contact Us

All comments and suggestions about this web site are very welcome and a valuable source of information for us. Thanks!

Tel: +(92) 302 970 8985-6

Email: This email address is being protected from spambots. You need JavaScript enabled to view it.


This website is certified by Health On the Net Foundation. Click to verify. This site complies with the HONcode standard for trustworthy health information:
verify here.

Our Sponsors

InsightGadgets.comPathLabStudyTheMedicalLibrary.orgThe Physio

By using you agree to our use of cookies to enhance your experience on this website.