Ch13 Flashcards
How many synapses do autonomic reflexes have?
All autonomic reflexes are polysynaptic, they have ganglia
What are alpha motor neurons? Where is the soma and first synapse?
Somatic motor neurons whose body is in the motor cortex and first synapse in the spinal cord. They are for skeletal muscles
What are effectors in the somatic nervous system?
Contractile skeletal muscle fibers, or extrafusal muscle fibers
What do gamma motor neurons innervate?
The intrafusal fibers controlling contraction of the muscle spindle
What sort of nervous output does the muscle spindle exhibit?
Tonic
What is the importance of alpha and gamma motor neuron co-activation?
This keeps the muscle spindle mostly isometric, providing a baseline output for maintaining resting muscle tone
What does the afferent signal from the golgi tendon organ do?
Leads to polysynaptic pathway that inhibits alpha motor neurons and forces muscle relaxation
What is the golgi tendon organ made of?
Free nerve endings intertwined with collagen inside a connective tissue capsule
Where are locomotor patterns of movement generated?
Spinal cord (with higher center input to initiate)
What kinds of muscle contractions do not need to be integrated in the cortex?
Postural and spinal reflexes
What are the 3 phases of voluntary movements?
Planning, initiation, and execution
Where do most corticospinal pathways crossover? Where do the minority?
The pyramids of the brainstem
Some crossover in the spinal cord, some not at all
What type of axons run in the corticospinal tract?
Interneurons for somatic motor control
What is a feedforward response?
Body adjustments in anticipation of a future stimulus
What brain structure is degenerated in Parkinson’s disease?
Basal ganglia neurons that release dopamine
