Reflex Pathways

Question 1

Any involuntary action or response evoked by a stimulus

Answer 1

reflexes

Question 2

preprogrammed (knee jerk, inverse stretch, crossed extensor)

Answer 2

innate reflexes

Question 3

walking, speaking, and writing are examples of what types of reflexes

Answer 3

learned reflexes

Question 4

direct meeting of receptor to effector
stretch reflex is the only example

Answer 4

monosynaptic reflexes

Question 5

interneurons found between receptor and effector
all reflexes BUT knee jerk

Answer 5

polysynaptic reflexes

Question 6

connections involving one layer of the spinal cord

Answer 6

unisegmental

Question 7

involvement of several segments of the spinal cord

Answer 7

multisegmented

Question 8

response of the same side of body as receptor signal

Answer 8

ipsilateral

Question 9

response on opposite side of body of receptor

Answer 9

contralateral

Question 10

bind muscles together

Answer 10

facia capsules

Question 11

bulk of contractile elements in muscles

Answer 11

extrafusal fibers

Question 12

nerves that stimulate extrafusal contraction

Answer 12

alpha motor efferents

Question 13

Intrafusal Fibers

Answer 13

sensory unit, found in the center of muscle spindles, striated at ends

Question 14

contain Annulospiral endings
lowest threshold for response
Type 1A A Primary Afferent signals

Answer 14

Nuclear Bag Fibers

Question 15

Flower Spray Organs
higher firing threshold than Nuclear Bag
Type 2 afferent fibers, Type 1A afferent fibers

Answer 15

Nuclear Chain Fibers

Question 16

Stimulate contraction of intrafusal fibers for tensioning of spindle “sensor unit”

Answer 16

Gamma Motor Efferent

Question 17

the 4 motor reflex pathways

Answer 17

1. Myotatic, Stretch, or Knee Jerk Reflex
2. Inverse Stretch Reflex
3. Withdrawal Reflex
4. Crossed Extensor Reflex

Question 18

as a muscle or tendon is stretched, increased firing of sensory afferent fibers, motor efferent fibers stimulated in the spinal cord, prevents overstretch of muscle

Answer 18

Myotatic, Stretch, or Knee Jerk Reflex

Question 19

this stimulated contraction against antagonist muscle

Answer 19

submaximal stretch

Question 20

at the same time as a stimulated contraction there is an inhibition of antagonistic muscle

Answer 20

large stretch

Question 21

response to contraction of extrafusal fibers
efferent signal set to spindle for retensioning
activation causes intrafusal fibers to shorten
increases spindle activity
initiates impulses from 1a fibers
allows spindle to contract and catch up to contracted extrafusal fibers

Answer 21

role of Gamma Motor Efferents

Question 22

polysynaptic reflex invoked when movement required excessive muscle strength, activates receptor called Golgi Tendon Organ, inhibits contraction of the actively contracting muscle and stimulates contraction of the antagonistic muscle

Answer 22

Inverse stretch Reflex

Question 23

removal of limb from noxious stimulus, stimulatory for ipsilateral flexors, inhibitory for ipsilateral extensors,

Answer 23

Withdrawal reflex

Question 24

if posture is involved in a withdrawal reflex, stimulatory for contralateral extensors, inhibitory for contralateral flexors

Answer 24

Crossed Extensor Reflex

Question 25

reaction time

Answer 25

time between stimulus and response

Question 26

Central delay =

Answer 26

reaction time - conduction velocity

Question 27

minimum synaptic delay

Answer 27

.5 msec

Question 28

reverberating circuits

Answer 28

stimulatory: found esp in respiration control loops
Renshaw cells: create reverberating inhibitory circuits that shut down reflexes

Question 29

Jendrassik’s Maneuver

Answer 29

clasped hands during knee jerk reflex
facilitates knee jerk reflex
increased gamma efferent discharge

Question 30

brain stem functions

Answer 30

blood pressure, respiration rate, wakefulness, posture and walking

Question 31

Reticular formation

Answer 31

posture
if severed, decerebrate rigidity

Question 32

Lesion between the brain and spinal cord produces

Answer 32

Spinal shock, loss of all reflexes, then hyperactive reflexes