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Terms in this set (23)
what is a reflex?
rapid, predictable, involuntary motor response to stimuli
what are the 5 components of the reflex arc?
receptor (stimulus), sensory neuron (afferent), integration center, motor neuron (efferent), and effector
what is the babinski sign?
occurs after the sole of the foot has been firmly stroked, the big toe moves upward toward the top surface of the foot and the other toes fan out
what is an inborn reflex?
a reflex that is a natural unlearned response to a stimulus, ex. suckling
what is a learned reflex?
association related, result of practice and repetition, ex. driving a car
what are the two classifications of reflexes?
Somatic and autonomic
What doe somatic reflexes activate?
what structures are involved in somatic reflexes?
muscle spindles and golgi tendon organ
what does muscle spindles do?
sense the length of the muscle and are sensitive to stretch. If a muscle is stretched the spindles sends a signal to the muscle that is being stretched to flex
what does the golgi tendon organ do?
located in the tendon, and it senses tension on muscle and associated tendons. the sensory fiber sends information to CNS via sensory fiber
what are examples of somatic reflexes?
stretch reflex, golgi tendon organ reflex, and crossed-extensor reflex
what is the stretch reflex?
caused by a stretch in muscle and involves muscle spindles.
steps: the muscle is stretched in the quad, spindle sense stretch and sends afferent signal to spinal cord, afferent neuron synapses with motor neuron of quad and inhibitory neurons of hamstring, the result is the quad contracts and the hamstring relaxes
what is the overall effect of stretch reflex?
stretched muscle will be activated and antagonist will be inhibited
what is the golgi tendon organ reflex?
caused by tension on muscle/tendon.
steps: high tension in muscle/tendon activates GTO, afferent impulse to spinal cord then to the cerebellum, simultaneously motor neurons are activated. The agonist motor neuron is inhibited and the antagonist motor neuron is activated, the result if quad is inhibited and hamstring is activated
what is the overall effect of the golgi tendon organ reflex?
muscles where tension is too high will be inhibited and antagonist muscles will be activated
what is the crossed-extensor reflex?
accompanies flexor reflex, and it is important to balance. Afferent sensory fibers from right arm to spinal cord interneurons, efferent motor responses to right arm exciting stretched muscle inhibiting antagonists (arm flexes). Efferent motor response to left arm inhibiting flexors and exciting extensors (arm extends)
ex. someone grabs your arm unexpectedly and the other arm reaches out
what are autonomic reflexes?
mediated through the ANS, and aren't usually aware of them. They regulate body functions like digestion, elimination, blood pressure, salivation, and swallowing
what do autonomic reflexes activate?
smooth and skeletal muscles and glands
what does monosynaptic mean?
a single chemical synapse, only 2 neurons involved (1 sensory and 1 motor)
ex. Knee jerk reflex
what does polysynaptic mean?
involves 1 or more interneurons in reflex arc pathway
ex. flexor reflex
what is the brain's role in reflexes?
reflexes don't have to go through the brain but the brain obtains afferent information via afferent sensory tracts of the spinal cord, not all reflexes involve thinking
what is hyperflexia?
overactive or overresponsive reflexes. occurs when there is an injury to a lower motor neuron
what is hypoflexia?
below normal or absent reflexes. occurs when there is an injury to an upper motor neuron
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