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20 Cards in this Set

  • Front
  • Back
Spinal Reflexes
Involve spinal nerves and the spinal cord
Cranial Reflexes
Involve cranial nerves and brain; therefore, the CNS is always part of a reflex arc since the impulse passes through the spinal cord
Somatic Reflexes
Involve contraction of skeletal muscles
Visceral Reflexes
involve contractions of smooth and cardiac muscles and secretion of glands
Which muscles receive reciprocal innervation?
antagonistic muscles
How are reflex arcs used?
Used to make fast, predictable automatic movements to help maintain homeostasis
What are the parts of the most simple reflex arcs?
1. a sensory receptor
2. a sensory neuron
3. a synapse or integrating center (may contain association neurons or interneurons)
4. a motor neuron
5. an effector
controls muscle length - causes contraction of a muscle that has been stretched - monosynaptic, ipsilateral - stimulates muscle spindles - sends contraction impulse to the same muscle (monosynaptic & ipsilateral) - also sends relaxation impulse (polysynaptic) to antagonistic muscle
FLEXOR (withdrawal) REFLEX
stimulates pain receptors - causes withdrawl of a part of the body in response to a painful stimulus - polysnaptic & ipsilateral - sends contraction impulses to many flexor muscles of the involved extremity (polysynaptic, intersegmental & ipsilateral)
controls muscle tension - causes relaxation of the muscle attached to the stimulated tendor organ - polysnaptic & ipsilateral - stimulates Golgi tendon organs - sends releaxation impulse to same muscle (polysnaptic and ipsilateral) - also sends contraction impulse (polysynaptic) to antagonistic muscle
used in conjunction with flexor reflex - sends impulses to other side of spinal cord to cause extension of musculature of other extremity for balance (polysynaptic, intersegmental & contralateral)
patellar reflex -
Achilles reflex -
Babinski sign -
plantar flexion reflex
Patellar Reflex
knee jerk; stretch of quadriceps
Achilles reflex
ankle jerk, stretch of plantar flexors
Babinski sign
stroke outer margin of sole of foot;in infants, extension of great toe; after 1 1/2 y0, plantar flexion reflex (curling under of toes, inturning of foot
All monosynaptic reflexes are
Intersegmental reflex arc
Occuring during the flexor reflex, when nerve impulses from one sensory neuron ascend and descend in the spinal cord and activate interneurons in several segments of the spinal cord
Contrast monosynaptic Stretch Reflex with polysnaptic Flexor Reflex
The MONOSYNAPTIC STRETCH REFLEX involves muscles receiving nerve impulses from one spinal cord segment only. The POLYSYNAPTIC FLEXOR REFLEX involves contraction of more than one muscle group, hence several motor neurons must sumultaneously convey impulses to several limb muscles
Contralateral Reflex Arc
Sensory impulses enter one side of the spinal cord, and motor impulses exit on the opposite side.
How does reciprocal innervation occur in the flexor and crossed extensor reflexes?
When the flexor muscles of a painfully stimulated lower limb are contracting, the extensor muscles of the same limb are relaxing to some degree. Because of reciprocal innervation, one set of muscles contracts while the other relaxes.