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Chapter 14: The Nervous System Part 3 - Reflex Actions


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Chapter 14: The Nervous System Part 3 - Reflex Actions

  1. 1. Coordination and responseWhite vs grey matter in spinalcord and brain
  2. 2. Transverse sections of spinal cord at different levels
  3. 3. Central Nervous System (spinal cord)grey matter(the butterflyshape; consist central canalof cell bodies (containsof neurones) cerebrospinal fluid  bringswhite matter nutrients to(consists of spinal cord)nerve fibers)  The opposite arrangement is found in the cortex of the brain.
  4. 4. Spinal cord and spinal nervespg.261 - contains only sensory neurones - aggregation - contains nerve relay of cell bodies fibres from both of sensory dorsal and ventral neurones roots - contains only motor neurones
  5. 5. Reflex actions An 1immediate response to a 2specific stimulus 3without conscious control e.g. knee jerk, withdrawal of hand from hot object Simplest form of response Classified under – spinal reflex actions (controlled by spinal cord) - cranial reflexes (controlled by brain but not will; in head region)
  6. 6. When we touch a hot object….
  7. 7. Reflex arcConsists of1. Receptor or sense organ2. Sensory neurone3. Reflex centre (spinal cord or brain)4. Motor neurone5. Effector (muscle/gland)
  8. 8. Conditioned reflex a reflex action acquired from past experiences or learning with a stimulus which is originally ineffective in producing the response e.g Pavlov’s experiment
  9. 9. Pavlov’s Experiment The dogs salivation to meat powder is an unconditional reflex (no learning is involved) Over time, however, the dog comes to salivate at the sounding of the tone alone. When this occurs, a conditional reflex has developed
  10. 10. Conditioned reflex
  11. 11. Conditioning?
  12. 12. The NervousSystem in Mammals Quiz
  13. 13. Label the parts ofthe neuron cell body (13) dendrites (14) axon (15) myelin sheath (16).