block 5 lecture 11 spinal reflexes

Question 1

what are the three main types of movement?

Answer 1

reflex, rhythmic and voluntary

Question 2

what does the dorsal side of the spinal cord receive input from?

Answer 2

the senses

Question 3

how do the sensory nerves enter the spinal cord?

Answer 3

dorsal roots

Question 4

where does the spinal cord get bigger?

Answer 4

cervical and lumbar enlargements

Question 5

where is the cervical enlargement?

Answer 5

C3-T1

Question 6

where is the lumber enlargement?

Answer 6

L1-S1

Question 7

how are the motor neurons in the grey matter of the spinal cord organised?

Answer 7

somatotopically - in relation to the body

Question 8

what controls the axial parts of the body?

Answer 8

medial neurons

Question 9

what do lateral neurons control?

Answer 9

distal parts of the body

Question 10

what are alpha neurons part of?

Answer 10

final common pathway

Question 11

where do upper motor neurons remain?

Answer 11

the central nervous system

Question 12

what do lower motor neurons do?

Answer 12

send axons directly to muscles

Question 13

what are the head muscles controlled by?

Answer 13

motor neurons in the brain stem

Question 14

where are the muscles of the body motor neurons?

Answer 14

spinal cord

Question 15

where are alpha neurons found in the spinal cord?

Answer 15

ventral horn

Question 16

where do the alpha motor axons go?

Answer 16

the axons pass through the ventral root and through spinal nerve and terminate at neuromuscular juntsion

Question 17

why are the ALPHA motor neurons?

Answer 17

thickest neurons meaning very rapid conduction

Question 18

what is the main neurotransmitter in muscle control?

Answer 18

acetylecholine

Question 19

what does acetylecholine do?

Answer 19

initiate muscle contraction

Question 20

what does myelination allow?

Answer 20

saltatory conduction

Question 21

where is sensory input gathered from?

Answer 21

cerebral cortex, spinal interneurons, muscle spindle and skin

Question 22

what is the most common motor neuron disease?

Answer 22

ALS - amyotropic lateral sclerosis

Question 23

what happens in ALS?

Answer 23

progressive degeneration of the alpha motor neurons

Question 24

what are the symptoms of ALS?

Answer 24

muscle weakness, atrophy, difficulty breathing and swallowing and affect on cognitive function

Question 25

in ALS why are the eyes the last to be effected?

Answer 25

highly vasculated and highly innervated

Question 26

what is a possible cause of ALS?

Answer 26

too much glutamate in the brain

Question 27

what blocks glutamatergic neurotransmission?

Answer 27

riluzole

Question 28

does the sensory neurons always synapse with the interneurons in the reflex arc pathway?

Answer 28

may synapse directly with motor neuron

Question 29

where are muscle spindle in relation to normal muscle?

Answer 29

located parallel to muscle fibers

Question 30

what are normal muscle fibers called?

Answer 30

extrafusal muscle fibers

Question 31

what are the spindle muscle fibers called?

Answer 31

intrafusal

Question 32

how does the neuron carry information to the spinal cord?

Answer 32

1a afferent neuron wraps around the muscle spindle and goes into the dorsal root of the spinal cord

Question 33

what neuron innervate intrafusal muscle fibers?

Answer 33

gamma motor neurons

Question 34

what can muscle spindle detect?

Answer 34

changes on the muscle

Question 35

what is the stretch reflex?

Answer 35

myotactic reflex,

Question 36

what is the patella tendon tap?

Answer 36

this is a stretch reflex

Question 37

what happens when the tendon is tapped?

Answer 37

the quadriceps are stretched, 1a muscle spindle is activated, impulses travel to the spinal cord and activate motor neurons which release acetylecholine and contract the quads

Question 38

what is the stretch reflex reciprocal inhibition?

Answer 38

while stretch reflex is occurring, collateral branch send information to inhibitory interneruon to inhibit antagonistic muscle

Question 39

what does the mono synaptic stretch reflex control?

Answer 39

contracts agonist muscle

Question 40

what dose the reciprocal inhibition control?

Answer 40

inhibits antagonistic muscle

Question 41

in the inverse stretch reflex pathway what is the sensory organ?

Answer 41

golgi tendon

Question 42

where is the golgi tendon?

Answer 42

between tendon and muscle fibers, runs in series with the extrafusal fibers

Question 43

what happens in the inverse stretch reflex pathway?

Answer 43

it send out 1b afferent which synapses with interneruon in the spinal cord which inhibits the alpha motor neuron to stop muscle contracting

Question 44

what is the golgi tendon innervated by?

Answer 44

1b

Question 45

what is the threshold of the golgi tendon like?

Answer 45

very high - you need alot of contraction to activate

Question 46

what is the golgi tendon made up of?

Answer 46

collagen fibers

Question 47

how are the 1b activated?

Answer 47

force acts on the collagen fibers in the tendons to increase tension causing compression of the fibrils which activates dendrites of the 1b afferent

Question 48

what happens in the flexor withdrawl reflex?

Answer 48

nociceptors are activated, impulses are sent along afferent neurons………….