Lecture 6: Golgi Tendon Organ Flashcards
Spindles lie in ____:
Parallel
GTOs lie in ____:
Series
GTOs lie in between:
Muscle fibres and tendons
What type of afferent fibre innervates the GTO?
Ib
____ pound Ib afferent per GTO:
1
How many muscle fibres are within a GTO, and which different MUs are they from?
10-20, from many different MUs, not just one or two
Ib activation mechanism:
Free ending
Ib activation in GTOs:
- Mechanical deformation of the Ib afferent branches between the collagen fibres
- Opens mechanically gated channels, change in membrane potential and generation of AP
Non linear characteristics of GTOs:
- Not all muscle fibres go through a GTO
- Not all muscle fibres in a GTO are association with the Ib ending
- Increase in force does not always increase Ib firing
Level of force necessary to excite a GTO depends on ____:
Mode of activation
What kind of stretch activates GTO? Where does this kind of force go?
Passive stretch, about 2 Newtons
Passively applied force goes through connective tissue
Is the GTO designed to monitor force actively or passively?
Actively
Passively stretched muscles stimulate _____ in muscle spindles:
Extrafusal and intrafusal muscle fibres
Actively contracted muscles stimulate ____ in muscle spindles:
Alpha motor neurons
What effect does passive stretching have on muscle length in both GTOs and muscle spindles?
Stretches
What effect does active contraction have on muscle length in both GTOs and muscle spindles?
Shortens
Negative feedback of GTOs:
- Ib synapses on an inhibitory interneuron
- Ib interneurons inhibit the motor neuron pool of homonymous muscle
Reciprocal excitation of GTOs:
- Ib inhibits agonist motor neuron pool and synergist motorneuron pool
- Ib feedback facilitates the antagonist motor neuron pool. Balances excitability around the joint
