chapter 7 Flashcards
each muscle contains a collection of _________, arranged into bundles known as ____________.
muscle fibers
fascicles
muscle fibers contain bundles of smaller __________
myofibrils
the basic functional units of a muscle fibers attached to each end are __________
sacromes
the muscle also has proprioceptive (position sense) organs to provide ___________ to the nervous systems about its contraction and load.
sensory feedback
muscles that work in opposing pairs are called ___________
antagonistic muscles
______, such as triceps, extend a joint,
whereas _____, such as biceps, contract it.
extensors
flexors
type I fibers are specialized for _______ at the expense of ______ and _________
type II fibers are specialized for ________ and ________ at the expense of quickly becoming fatigued
endurance, power and speed
power and speed
motor neurons make contact with muscle fibers at a specialized structure called the _______________
neuromuscular junction
how does the contact at the neuromuscular junction resemble a synapse?
- the axon of a motor neuron ends in a flattened bulb/motor neuron terminal, which is analogous to the presynaptic axon terminal at a connection between two neurons
- the endplate on a muscle fiber is analogous to the postsynaptic cell membrane of a neuron
- the terminal and endplate membranes are separated by a narrow space, much like a neuron-to-neuron synapse
what happens when acetylcholine neurotransmission is blocked?
muscles can weaken or paralyze
______ and other medicines of its type block the binding of acetylcholine to its receptors on the muscle fiber endplates. They are derived from the ingredient _________.
rocuronium
curare
A _______ consists of alpha motor neuron and all of the muscle fibers it innervates.
motor unit
____________ detect sudden muscle stretch
proprioceptors
the anaerobic bacterium, Clostridium Tentani also produces a potent toxin, ________, which prevents the release of inhibitory neurotransmitter, with similar lethal effects.
tetanospasmin
At the level of the medulla, the descending axon bundles of the corticospinal tract are called the _________
the region where the axons cross over to the contralateral sides is called the __________
pyramids
pyramidal decussation
the rubrospinal tract sends input from the _________ of the brainstem to control movements of the limbs
red nuclei
the ___________ of the brainstem sends input to the spinal cord via the vestibulospinal tract
vestibular nuclei
the most elaborate forms of motor control rely on the extensive motor circuitry of the _________, _____________, and ___________.
cerebrum, basal ganglia, and cerebellum
what are recognized symptoms of cerebellar injury?
impairments in coordination, rhythm, magnitude, accuracy, and timing of movements in various parts of the body
in most species, locomotion requires _____ rather than _______ movements of the left and right sides of the body
alternating
simultaneous
_________ are excitatory interneurons that coordinate b/wn ipsi- and contralateral innervation
local circuits
type I fibers are specialized for _________ at the expense of ______ and ______
endurance
speed and power
type II fibers are specialized for _____ and _______ at the expense of being quickly ______
speed and power
fatigued
________ and other medications of its type block the binding of acetylcholine to its receptors on the muscle fiber endplate, preventing muscle contraction even if the motor neurons fire.
Rocuronium
At the neuromuscular junction, the released acetylcholine is broken down by an enzyme in the synaptic cleft, called ____________.
acetylcholinesterase
the _______ is home to the spinal cord motor neurons/ lower motor neurons
ventral horn
Many forms of motor control rely on circuits through the gray matter of the spinal cord. An example is a ___________: if a muscle is stretched suddenly and unexpectedly, it must contract to maintain position.
spinal reflex
_______ detect sudden muscle stretch
proprioceptors
_________ also produces a potent toxin, tetanospasmin, which prevents the release of inhibitory neurotransmitter, wh
clostridium tetani
locomotion requires _______ rather than ______ movements
alternating
simultaneous
the most important pathway in humans is the corticospinal tract, which contains axons that travel down from the ________ neurons of the primary motor cortex and connect to the lower motor neurons neurons of the _________
upper motor neurons
spinal cord
At the level of the medulla, the descending axon bundles of the corticospinal tract are called the ________.
pyramids
The rubrospinal tract sends input from the _______ of the brainstem to control movements of the limbs, particularly of the muscles such as the biceps and quadriceps.
red nuclei
the _________ of the brainstem send inputs to the spinal cord via the vestibulospinal tract.
vestibular nuclei
the _________ of the brainstem send inputs to the spinal cord via the vestibulospinal tract.
vestibular nuclei
what are inputs to the spinal cord via the vestibulospinal tract important for?
coordinating balance movement of the head, neck, trunk, and proximal limbs
the tectospinal tract sends inputs from the spatial localizing systems of the midbrain’s _______ to the spinal cord to help coordinate movements for capturing or avoiding moving targets in the surrounding environment.
tectum
the _________ is often injured in cerebral palsy
corticospinal tract
Several types of interneurons complete the circuitry of the cerebellum. _______ and _______ lie in the molecular layer
basket cells and stellate cells
What are the 3 layers of the cerebellar cortex?
1) an inner granule cell layer, packed with tiny neurons that make up most of the cerebellar population
2) a middle Purkinje cell layer, composed of a single thin layer of the large Purkinje cells that integrate information from the other neurons and send output back to the rest of the nervous system
3) an outer molecular cell layer: a communication zone filled with the axons of the granule cells, the dendrites of Purkinje cells, and various forms of small interneurons
the __________ nucleus is the cerebellum’s main input nucleus
inferior olivary
__________ fibers wrap around the Purkinje cells near the cell body and axon rather than the dendrites, providing powerful excitatory input that varies in time to modulate Purkinje cell activity
climbing fibers
_______ cells form connections from the parallel fibers back to the granule cells
Golgi cells
