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Lecture 4:

Lecture 4:. Reflexes and Spinal Circuits. Sensory systems. CNS. Movement. Afferent pathway. Efferent pathway. Reflex. A simple neural circuit example of sensory and motor systems. Involuntary action or movement that occurs in response to a stimulus.

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Lecture 4:

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  1. Lecture 4: Reflexes and Spinal Circuits

  2. Sensory systems CNS Movement Afferent pathway Efferent pathway

  3. Reflex... • A simple neural circuit example of sensory and motor systems. • Involuntary action or movement that occurs in response to a stimulus. For example: sneeze, cough, yawn, blink.

  4. Examples... • Cough, irritant enters the windpipe and we need to expel it through our mouth. • Sneeze, clear out nasal air passages of irritants and allergens.

  5. Sensory neurons: Also named afferent neurons: Carry messages to the CNS (brain and/or spinal cord).

  6. Motor neurons : Also named efferent neurons: Carry messages away from the CNS (brain and/or spinal cord).

  7. Each reflexive action usually involves more than two neurons between nerve cells (neurons).

  8. Interneurons • A nerve cell that forms synapses with sensory and motor neurons to integrate sensory input and motor output.

  9. Motor example:Knee Jerk Reflex (Patellar reflex)

  10. Knee Jerk reflex ... • Also named a monosynaptic reflex. (one connection, therefore two neurons)

  11. Monosynaptic reflex • Only one synapse in the neural circuit is needed to complete the reflex. • The tap below the knee causes the thigh muscle to stretch. • Information is sent to the spinal cord, where it’s sent back to the muscle and we get a reflex.

  12. Reflexes: • Serve as primitive responses to protect our bodies from danger. • Help us to adjust to our surroundings. Are all movements reflexive monosynaptic??

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