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Powerlab
N/A
36
Anatomy
Undergraduate 3
07/27/2011

Additional Anatomy Flashcards

 


 

Cards

Term
Iborn/Intrinsic reflex
Definition
a rapid, predictable motor response to a stimulus
Term
Learned/acquired reflex
Definition
results from practive or repetition
Term
reflex arcs
Definition
highly specific paths where reflexes occur
Term
Receptor
Definition
Site of the stimulus action
Term
Sensory neuron
Definition
Transmits afferent impulses to the CNS
Term
Integration center
Definition

In simple reflex arcs, the integration center may be a single synapse between a sensory neuron and a motor neuron

 

More complex reflex arcs involve multiple synapses with chains of interneurons

Term
Monosynaptic reflex
Definition
single synapse between a sensory neuron and a motor neuron
Term
Polysynaptic reflex
Definition
multiple synapses with chains of interneurons
Term
Motor neuron
Definition
Conducts efferent impulses from the intergration center to an effector organ
Term
Effector
Definition
muscle fiber or gland cell that responds to the efferent impulses (by contracting or secreting)
Term
Somatic reflexes
Definition
activate skeletal muscle
Term
Autonomic (visceral) reflexes
Definition
activate visceral effectors (smooth or cardiac muscle or glands)
Term
spinal reflexes
Definition

somatic reflexes mediated by the spinal cord

 

occur without the direct involvement of higher brain centers

Term
muscle spindles
Definition
supply information to CNS about the lenfth of a muscle
Term
Golgi tendon organs
Definition
supply information to CNS about the amount of tension in a muscle and its associated tendons
Term
intrafusal muscle fibers
Definition
modified skeletal muscle fibers; muscle spindls consists of three to ten
Term
extrafusual muscle
Definition
effector fibers of the muscle
Term
primary sensory endings of large type Ia fibers
Definition
innervate the spindle center and are stimulated by both the rate and degree of stretch
Term
secondary sensory endings of small type II fibers
Definition
supply the spindle ends and are stimulated only by degree of stretch
Term
gamma efferent fibers
Definition
arise from small motor neurons in the ventral horn of the spinal cord; maintain spindle sensitivity
Term
alpha efferent fibers of the large alpha motor neurons
Definition
stimulate the extrafusal muscle fibers to contract
Term
alpha-gamma coactivation
Definition
Descending fibers of motor pathways synapse with both alpha and gamma motor neurons, and motor impulses are simultaneously sent to the large extrafusal fibers and to muscle spindle intrafusal fibers. Stimulating the intrafusal fibers maintains the spindle's tension (and sensitivity) during muscle contraction, so that the brain continues to be notified of conditions in the muscle.
Term
stretch reflex
Definition
makes sure the muscle stays at that length
Term
patellar or knee-jerk reflex
Definition
a strech reflex that helps keep your knees from buckling when you are standing upright
Term
reciprocal inhibition
Definition
branches of the afferent fiberls synapse with interneurons that inhibit motor neurons controlling antagonistic muscles
Term
monosynaptic and ipsilateral
Definition
involve a single synapse and motor activity on the same side of the body
Term
polysynaptic
Definition
reflex arcs that inhibit the motor neurons serving the antagonistic muscles
Term
polysynaptic Golgi tendon reflex
Definition
muscle relaxation and lenthening in response to tension
Term
reciprocal activation
Definition
motor neurons in the spinal cord circuits supplying the contracting muscle are inhibited and antagonist muscles are activated
Term
flexor/withdrawal reflex
Definition
initiated by a painful stimulus and causes automatic withdrawal of the threatened body part from the stimulus
Term
Crossed-extensor reflex
Definition
accompanies the flexor reflex in weight-bearing limbs and is particulary important in maintaining balance
Term
superficial reflexes
Definition
elicited by gentle cutaneuos stimulation such as that produced by stroking the skin with a tongue depressor; depend on functional upper motor pathways and on cord-level reflex arcs
Term
plantar reflex
Definition
tests the integrity of the spinal cord from L4 to S2 and indirectly determines if the corticospinal tracts are functioning properly
Term
Babinski's sign
Definition
the great toe dorsiflexes and the smaller tows fan laterally
Term
abdominal reflexes
Definition
Check the integrity of the spinal cord and ventral rami from T8 to T12; stroking the skin of the lateral abdomen above, to the side, or below the umbilicus induces a reflex contraction of the abdominal muscles in which the umbilicus moves toward the stimulated site
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