spinal cord: tendon reflex

Overview of Spinal Cord Reflexes

Reflex: An automatic, rapid response to a stimulus, mediated at the spinal cord level.

Patellar Stretch Reflex:
- Example of a spinal reflex observed in a prior video.
- Involves two reflex arcs working together to produce the response (kicking leg).
- Reflex assessments are used clinically to evaluate nervous system integrity.

Introduce a new example of a spinal reflex.
Identify components of the reflex arc.
Compare and contrast the reflex arc as:
- Monosynaptic or polysynaptic.
- Ipsilateral or contralateral.
Reference: Saladin's textbook, pages 493 to 499.

Visual Representation:
- Color-coded schematic:
  - Sensory neurons (blue)
  - Motor neurons (red)
  - Interneurons (purple)
  - Stimulatory synapses (+) and inhibitory synapses (−)

Receptor: Golgi tendon organ (tendon organ)
- Located in the tendon near the muscle.
- Activated by muscle tension increases.
Sensory Neuron:
- Generates graded potentials in response to receptor activation.
- If graded potentials meet threshold, action potentials are generated in sensory neurons.
- Action potentials travel to the spinal cord via the dorsal root.
Interneurons:
- Form synapses with sensory neurons and motor neurons.
- Specifically, the inhibitory interneuron inhibits the next neuron in line (motor neuron).
Motor Neuron:
- Receives inhibitory signals from the interneuron, reducing action potentials.
- Resulting in decreased release of acetylcholine at the muscle.

Outcome:
- Reduced muscle contraction leads to relaxation of the muscle.
- Protects the tendon from damage caused by excessive tension.