Spinal reflexes

Question 1

what is a reflex

Answer 1

reflex is coordinated involuntary movement - initiated by the brain

Question 2

reflexes can sometimes involve

Answer 2

supraspinal components

Question 3

what is supra spinal components

Answer 3

something above part of the spine - can be the brain or ligaments or fascia

Question 4

why do reflexes occur

Answer 4

in response to danger

Question 5

what is the stretch reflex

Answer 5

a monosynaptic reflex which lengthens the skeletal muscle

Question 6

how is the stretch reflex evoked

Answer 6

tendon tap

Question 7

what does a stretch reflex rely on

Answer 7

mechanical response and sensory afferent feedback

Question 8

how do u abolish the stretch reflex

Answer 8

cutting dorsal root

Question 9

muscle spindles are receptors that detect changes in the

Answer 9

muscle length during contraction

Question 10

the stretch in stretch reflex evokes an increase in

Answer 10

spindle firing rate

Question 11

the sensory signal in the stretch reflex is sent to where

Answer 11

dorsal horn by type 1a afferent neurons

Question 12

a motor neurons are activated in the spinal ventral horn leading to

Answer 12

muscle contraction of the agonist and synergist muscles

Question 13

stretch reflex - what muscles are inhibited

Answer 13

antagonist

Question 14

muscle spindles consist of what

Answer 14

bundles of thin fibres contained within capsule

Question 15

9spindles) situated in parallel with main intrafusal muscle fibres but

Answer 15

generates no force

Question 16

muscle spindles wrapped around by what

Answer 16

sensory axons - 1a and 2

Question 17

muscle spindles have y motor neurons cause active contraction of

Answer 17

spindles

Question 18

muscle spindle detects - 2

Answer 18

length and stretch of muscle - position
and rate of change - velocity

Question 19

intrafusal fibres are innervated by what

Answer 19

y motor neurons

Question 20

what are the 2 types of intrafusal fibres

Answer 20

• nuclear bag fibres - 1a afferents- annulospiral endings
  -nuclear chain fibres - both 1a and 2 afferents

Question 21

what is bigger intrafusal fibres

Answer 21

nc. bag fibres - bc of nuclei bunched together

Question 22

both types of intrafusal fibres respond to

Answer 22

stretch

Question 23

stretch reflex-
faster the response means

Answer 23

the fewer neurons and synapses

Question 24

u can use latency in a reflex to calculate what

Answer 24

how many neurons involved

Question 25

the earliest onset is what for stretch reflex

Answer 25

<1ms

Question 26

stretch reflex - the antagonist muscles are inhibited at

Answer 26

slightly longer latencies

Question 27

reciprocal inhibition antagonist muscles which may interfere with ...

Answer 27

desired movement are suppressed by contraction of the agonist muscle

Question 28

reciprocal inhibition co contraction is what

Answer 28

when we want to contract antagonist and agonist at the same time

Question 29

why is reciprocal inhibition useful

Answer 29

to help stop co contraction and modulates inputs from the brain

Question 30

what is klippel feil syndrome

Answer 30

a rare condition in which premotor neurons from cortex bifurcate to innervate both sides of the body

Question 31

moving one hand ipsilateral leads to

Answer 31

mirror movements in other hand

Question 32

hyperreflexia / spasticity

Answer 32

descending input from the brain normally acts to regulate reflex gain in spinal cord

Question 33

what can abolish the input for hyperrflexia

Answer 33

sci, stroke and other conditions

Question 34

what is Intrathecal baclofen

Answer 34

treatment for spasticity

Question 35

what is the proceedure is intrathecal baclofen -

Answer 35

catheter is placed in spinal fluid and a pump in the abdominal which pumps baclofen - allowing dorsal horn inhibition

Question 36

what does the treatment for specificity result in

Answer 36

decreased ,muscle spasms and tone

Question 37

what is the purpose of the stretch reflex

Answer 37

it is a negative feedback loop preventing major disturbances to regulation of controlled variable - muscle length

Question 38

what does the stretch reflex maintain

Answer 38

accuracy of movement (in face of small deviations)

Question 39

voluntary commands come from which part of the brain

Answer 39

motor cortex

Question 40

the stretch reflex helps correct what

Answer 40

small deviations from desired trajectories caused by unpredictable things

Question 41

an unpredictable increase in load is a disturbance detected by

Answer 41

muscle spindles and will compensate for deviation from desired muscle length

Question 42

what is the Hoffman reflex

Answer 42

the finger reflex, which identifies possible problems within the corticospinal tract

Question 43

what does the hoffman reflex do

Answer 43

evokes a muscle contraction from type 1a sensory nerves

Question 44

what can hoffman reflex be shown on

Answer 44

EMG

Question 45

sensory type 1a afferent fibres are activated at a what threshold than motor fibres

Answer 45

lower

Question 46

how can the hoffman reflex be altered

Answer 46

conditioning a stimulus

Question 47

what is flexion withdrawal reflex

Answer 47

A reflex which contracts a muscle in response to danger or pain

Question 48

the flexion withdrawal reflex stimulates what

Answer 48

ipsilateral flexor muscles whilst extensors are inhibited

Question 49

what type of fibres in withdrawal reflex

Answer 49

thinly myelinated type 3

Question 50

withdrawal reflex provides extension in

Answer 50

contralateral limb to compensate for unloading in the ipsilateral limb

Question 51

the reflex withdrawal reflex persists after spinal cord what

Answer 51

transection

Question 52

reflex adaptability - golgi tendon input inhibits what

Answer 52

ongoing muscle activity via negative feedback

Question 53

Golgi tendons are sensitive to tension and force and active what type of afferent neurons

Answer 53

type 1b

Question 54

what is locomotion

Answer 54

movement or ability to move from one place to another

Question 55

during lococmotion - golgi tendons input increases extension muscles a activity to produce what

Answer 55

positive feedback

Question 56

gait phase dependant golgi feedback - GTO reflex contributes to transition between what 2 phases

Answer 56

stance and swing

Question 57

what type of feedback is during the gait phase of stance

Answer 57

positive

Question 58

what type of feedback is used for swing gait phase

Answer 58

negative

Question 59

what is pulmonary stretch receptors

Answer 59

receptors which monitor the mechanoreceptors in the lungs

Question 60

what is the pulmonary stretch reflex

Answer 60

The reflex which monitors coughing and lung inflation - mediated by the receptors

Question 61

rapidly adapting receptors lie between what 2 cells

Answer 61

airway epitheial cells and trigger the cough reflex

Question 62

slowly adapting receptors lie in between what 2 things

Answer 62

airway smooth muscle cells and the trigger the lung inflation reflex

Question 63

what fibres trigger the cough reflex

Answer 63

RARS activting Ao and C fibres

Question 64

cough reflex is what

Answer 64

a mechanism for airway defense's against aspiration

Question 65

irritatnt receptors are a type of what

Answer 65

nociceptor

Question 66

mechanical stimuli for cough reflex involves what

Answer 66

bronchoconstriction -dust - food - chemicals - activating type 3 fibres

Question 67

first step for affernt information travelling to medulla and then to

Answer 67

respiratory central pattern generators in brain stem

Question 68

effectors for cough reflex is what

Answer 68

inspiratory, expiratory and upper airway muscles

Question 69

mechanics of breathing what are the 3 phases for a cough

Answer 69

inspiratory, compression and expiratory

Question 70

inspiration breathing what are the 2 steps for cough - inspiratory

Answer 70

deep inspiration with the glottis open diaphragm external intercostals

Question 71

what is the compression phase for a cough

Answer 71

expiratory muscle contract - against closed glottis - making pressure trunk and upper airway compress

Question 72

what is the phase for expiratory phase for a cough

Answer 72

glottis opens causing a rapid ejection

Question 73

stretch relfex is caused by what

Answer 73

msucle spindles