reflexes and reflex arcs Flashcards
(16 cards)
What triggers action potentials in sensory neurons?
A stimulus at the receptor.
What type of synapses are typically shown?
Excitatory
What’s the structure of somatosensory neurons?
Pseudo-unipolar.
Monosynaptic arc?
One synapse (e.g., knee jerk).
: Disynaptic arc?
One interneuron.
: Trisynaptic arc?
Two interneurons.
Polysynaptic arc?
A: More than three neurons involved.
What is the phasic stretch reflex?
Only monosynaptic skeletomotor reflex.
What does it respond to?
Speed of muscle stretch, not length.
Involves brain?
No, it’s a spinal reflex.
Type Ia endings respond to?
Speed of stretch (fast adapting)
Type II endings respond to?
Amount of stretch (slow adapting).
What causes knee jerk?
Fast stretch detected by Ia afferents.
: Are reflexes always simple, fixed, and innate?
No, many are complex, variable, and influenced by experience.
Examples of complex reflexes?
Coughing, sneezing, swallowing, vomiting.
Why does a tendon tap trigger a reflex despite little stretch?
Because it’s very fast, activating Ia afferents.
