____ control movement. A proprioceptor is a receptor that detects the position or movement of a part of the body – in these cases a muscle.
Muscle proprioceptors detect the ____ and ____ of a muscle and send messages that enable the spinal-cord to adjust its signals.
stretch and tension
When a muscle is stretched, the spinal-cord sends a reflexive signal to contract it. This ____ ____ is caused by a stretch; it does not produce one.
One kind of proprioceptor is the ____ ____, a receptor parallel to the muscle that responds to stretch.
Whenever the muscle spindle is stretched, it's sensory nerve sends a message to a ____ ____ in the spinal-cord, which in turn sends a message back to the muscles surrounding the spindle, causing a contraction.
____ ____ ____, also proprioceptors, respond to increases in muscle tension. Located in the tendons at opposite ends of a muscle, they act as a brake against an excessively vigourous contraction.
Golgi tendon organs
Some muscles are so strong that they could ____ themselves if too many fibres contracted at once. Golgi tendon organs detect the tension that results during a muscle contraction. Their impulses travel to the spinal-cord, where they excite interneurons that inhibit the motor neurons.
In short, a vigorous muscle contraction ____ further contraction by activating the Golgi tendon organs.
The proprioceptors not only control important reflexes but also provide the ____ with information.
Different kinds of movement depend on different kinds of control by the ____ ____.
____ are consistent automatic responses to stimuli. We generally think of reflexes is involuntary because they are insensitive to reinforcements, punishment, and motivations.
Even when a ____ to a stimulus is not a reflex, it differs from a spontaneous behaviour.
When you react to a stimulus, you move faster than when your action is ____.
If you place an object firmly in an infants hand, the infant grasps it (the ____ reflex). If you stroke the sole of the foot, the infant extends the big toe and fans the others (the ____ reflex). If you touch an infants cheek, the infant turns toward the stimulated cheek and begins to suck (the ____ reflex).
grasp : Babinski : rooting
A ____ missile is launched like a thrown ball: once it is launched, no one can change its aim. A guided missile detects the target and adjust its trajectory to correct its aim.
Some movements are ballistic, and others are corrected by feedback. ____ ____ is executed as a whole: once initiated, it cannot be altered. Reflexes are ballistic.
Many of our behaviours consist of rapid sequences, as in speaking, writing, dancing, or playing a musical instrument. Some of these sequences depend on ____ ____ ____ – mechanisms in the spinal-cord that generate rhythmic patterns of motor output.
central pattern generators
Although a stimulus may activate a central pattern generator, it does not control the ____ of the alternating movements.
A fixed sequence of movements is called a ____ ____.
Once began, the sequence is ____ from beginning to end.
____ have built in motor programs. Yawning is an example. Certain facial expressions are also programmed, such as smiles, frowns, and the raised eyebrow greeting.