16 Somatosensory Receptors

20 2010 two groups of afferents coming from muscle

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: - Two groups of afferents coming from muscle spindle: - Both slowly-adapting - Ia (big ones): strong dynamic sensitivity - Respond to rate of change of stimulus - i.e. at beginning of stretch - Sensitive to velocity of stretch - II: more statically sensitive Somatosensory Receptors - Weak response to rate of change - Main response to size of stimulus (sustained part) Golgi tendon organ Group Ib Proprioceptor: Golgi tendon organ Located at junction of muscle fibers with - Completely diff focus: activated by active contractile force tendon generated by muscle terminal branches of group Ib sensory axon entwined with collagen fibers of tendon - Contraction removes tension: gamma motoneurons distorted by force of active contraction slowly-adapting resensitive muscle spindles - Opposite of Golgi tendon organ - Located at jxn of muscle fibers w/ tendon (which joins to bone) - Terminal branches of group Ib sensory axon interspersed and entwined among collagen fibers of tendon - Muscle contraction: pull on collagen fibers & squeeze them together - Squeeze on axon terminals = receptor potential -> a.p. - Slowly-adapting: discharge a.p. throughout duration of stimulus - Whereas Ia afferents: muscle shortening = stop firing - Gamma motoneurons can re-sensitive spindle? No: w...
View Full Document

Ask a homework question - tutors are online