Lecture 14 - neuro reflex

Question 1

Which reflex(s) cross the cord?

Answer 1

crossed-extensor

Question 2

Which reflex purpose is to keep muscles at a constant length, weight-bearing support?

Answer 2

Stetch/ muscle spindle

Question 3

Which reflex serves to cease muscle contraction under heavy load to prevent muscle from tearing off bone?

Answer 3

Tendon

Question 4

which reflex serves to withdraw limbs from painful stimuli to prevent injury

Answer 4

Withdrawal/Flexor

Question 5

Which reflexes involve multiple levels of the spinal cord above and below?

Answer 5

Pain reflexes:
Withdrawal/Flexor and Crossed-extensor

Question 6

Where are the ascending and descending interneurons located?

Answer 6

Located in the white matter of dorsal border of dorsal horn = “Tract of Lissauer”

Question 7

Which variation of nACh-Receptors are located only at the NMJ?

Answer 7

mature/adult

Question 8

Which variation of nACh-Receptors can be located outside of the NMJ?

Answer 8

Immature/”fetal nACH-R”

Question 9

Which variation of nACh-Receptors are comprised of 5 alpha domains? where is it located in the body?

Answer 9

alpha 7, CNS

Question 10

Which type of nACh-R is comprised of
2 alpha binding domains
1 epsilon
1 beta1
1 delta

Answer 10

mature/adult

Question 11

Which type of nACh-R is comprised of
2 alpha binding domains
1 gamma
1 beta1
1 delta

Answer 11

immature/”fetal”

Question 12

Which nACh-R has high conductance?

Answer 12

mature/adult

Question 13

Which nACh-R has low conductance?

Answer 13

immature/fetal

Question 14

What does it mean if a channel has “high conductance”?

Answer 14

when open, the speed that ions move through the channel is high. They close faster as well.

low conductance= lower speed

Question 15

Which nACh-R is worse for succinylcholine to bind to, resulting in much higher levels of K+ leakage?

Answer 15

immature/fetal

Question 16

What are the 4 reflex pathways?

Answer 16

Stretch
Tendon
Withdrawal
Crossed Extensor

Question 17

An _______ is a bridge between a sensory neuron and a motor neuron

Answer 17

Interneuron - can also allow cross-over

Question 18

Are interneurons excitatory or inhibitory?

Answer 18

Can be either

Question 19

Do interneurons travel vertically or horizontally?

Answer 19

Can be either

Question 20

Stretch reflex usually ______ have interneurons and ______ cross the cord

Answer 20

doesn’t and doesn’t

Question 21

What is the purpose of interneurons in the stretch reflex if they are present?

Answer 21

Inhibitory interneurons that allow reflex relaxation of the antagonistic muscle set

Question 22

Which reflex is responsible for maintaining posture?

Answer 22

Stretch

Question 23

What are the springs called that sense how much tension is in the muscle for the stretch reflex?

Answer 23

Muscle spindle = stretch receptor

Question 24

Differentiate between a direct reflex arc and a secondary reflex arc

Answer 24

Direct reflex arc:
- Stretch-Contract
- Contract effector (quadriceps, eg)

Secondary reflex arc:
- Inhibitory interneuron
- Inhibit antagonist muscles (hamstring, eg)

Question 25

What are the sensors that detect tension of tendons on muscles for the tendon reflex?

Answer 25

golgi tendon sensors

Question 26

What are the two reflexes of the tendon reflex?

Answer 26

Reflex #1: Cease (inhibit) contraction under heavy load to prevent tendon tears Reflex #2: Contract (excite) antagonistic muscles to speed retraction from load source

Question 27

Flexor reflex alternate name

Answer 27

Withdrawal reflex

Question 28

Which pain reflex is used when static vs moving?

Answer 28

Flexor - static Crossed extensor - moving

Question 29

What are the two reflexes of the crossed extensor reflex?

Answer 29

Reflex #1: Several levels of left “hamstring” flexor motor output from spinal cord.  Withdraws left leg from painful stimuli. Reflex #2: Several levels of right “quad” extensor motor output from spinal cord.  Assures that we have good footing to use as a push-off point for #1 above.

Question 30

What are the simplest vs most complicated reflexes?

Answer 30

Simplest - stretch Most complicated - crossed extensor

Question 31

Pain receptors synapse on _______ in grey matter.

Answer 31

2nd-order interneurons

Question 32

How can you determine depth of a block with reflexes?

Answer 32

Reflex not present - block deeper

Question 33

If the nervous system doesn't get information back from muscle that contraction occurred, the body's response is to?

Answer 33

Put more ACh-R at the NMJ - Also end up on places other than NMJ (entire muscle) - Fetal nACh-R instead of mature

Question 34

ACh-R found in the NMJ are called _____

Answer 34

junctional

Question 35

ACh-R found in the borders of the NMJ are called _____

Answer 35

peri-junctional

Question 36

ACh-R found away from the NMJ are called _____

Answer 36

post-junctional

Question 37

_________ is a strong enough voltage to allow depolarization to generate an AP in the underlying neurons

Answer 37

Supramaximal stimulus - voltage that is strong enough stimulus to recruit all motor neurons/skeletal muscles

Question 38

TOF stimulation Hz/seconds

Answer 38

2 Hz over 2 seconds = 4 twitches

Question 39

Repetitive, high frequency stimulation for a short period of time

Answer 39

Tetanic contraction

Question 40

_________ - impulses after tetanic contraction

Answer 40

Post-tetanic count (PTC)

Question 41

What kind of nerve stimulation shows the health of a synapse?

Answer 41

Post-tetanic count (PTC)

Question 42

A _______ is a series of tetanic contractions

Answer 42

DBS: Double-burst stimulation

Question 43

The ulnar nerve innervates the ______ muscle

Answer 43

Adductor Pollicis

Question 44

What happens with contraction of the Adductor Pollicis muscle?

Answer 44

thumb comes forward and/or pinky twitches

Question 45

What are the alternatives to neuromuscular monitoring in muscles other than the Adductor Pollicis?

Answer 45

- Ophthalmic branch of Facial nerve - Peroneal nerve - Posterior tibial nerve

Question 46

A _______ is a graphical depiction of underlying muscle activity to determine response

Answer 46

EMG

Question 47

What are the 3 ways to of neuromuscular monitoring?

Answer 47

Velocity meters EMG Visual assessment

Question 48

How quickly does sux begin to wear off?

Answer 48

3 min

Question 49

Differentiate between TOF stimulation of a NDMR vs Sux

Answer 49

NDMR: first contraction is the strongest (A), last contraction is the weakest (B) Sux: equal strength of contractions

Question 50

What is the TOF ratio?

Answer 50

B/A - Weakest contraction/strongest contraction - only works for NDMR - need all 4 stimuli to measure

Question 51

The Sux TOF ratio is always ___

Answer 51

1

Question 52

As the NDMR wears off, the TOF ratio does what?

Answer 52

Gets closer to 1

Question 53

Why are the contractions of the NDMR unequal, while the Sux contractions are equal?

Answer 53

muscle relaxants act on the motor neuron and the skeletal muscle - autoreceptors reduce amount of ACh being released from the motor neuron due to ion current (VP-1 to VP-2) - NDMR contractions differ because Sux primarily works on the skeletal muscle, not the motor neuron

Question 54

What is the makeup of autoreceptors?

Answer 54

3 alpha 2 beta

Question 55

What determines transition of VP-1 vesicles to VP-2?

Answer 55

- autoreceptors on the motor neuron ion current

Question 56

The more important a muscle is, the more ______ it is to polarize

Answer 56

difficult - more robust NMJ (more receptors)

Question 57

What spinal level does the phrenic nerve connect to the diaphragm?

Answer 57

C3-C5

Question 58

The _______ is a skeletal muscle that separates the abdominal cavity from the thoracic cavity

Answer 58

diaphragm

Question 59

What nerve connects C3-C5 to the diaphragm?

Answer 59

The phrenic nerve

Question 60

4th Twitch Disappears: ____% nACh-R’s blocked

Answer 60

~75-80%

Question 61

3rd Twitch Disappears: ____% nACh-R’s blocked

Answer 61

85

Question 62

2nd Twitch Disappears: ____% nACh-R’s blocked

Answer 62

~85-90%

Question 63

All Twitches Disappear when ____% nACh-R’s blocked

Answer 63

~90-95

Question 64

How high can a spinal nerve injury be and still be able to ventilate?

Answer 64

C4

Question 65

Would the diaphragm or the adductor pollicis muscle recover first from a paralytic?

Answer 65

Diaphragm

Question 66

A patient who is able to lift their head has ____% nACh-R’s blocked

Answer 66

70

Question 67

A patient can probably breath on their own when there are ____ twitches present on the TOF

Answer 67

all 4

Question 68

What is the normal setting for TOF?

Answer 68

50-80 mA - curent

Question 69

What are the 3 ways K+ is lost when Sux is bound to ACh-R?

Answer 69

1. leak channels 2. V-G K+ channel 3. K+ loss through ACh-R

Question 70

Which muscle is controlled by multiple motor neurons?

Answer 70

occular muscle in eye socket

Question 71

If you give sux to the skeletal muscle in the eye socket, what would you expect to happen?

Answer 71

Since multiple motor neurons control the muscle, you would expect increased IOP (increased Ca++ entry), putting stress on optic nerve - potential blindness

Question 72

What are the 2 most important inhibitory NTs in the spinal cord?

Answer 72

GABA and glycine

Question 73

What are the 3 NT that increase CNS activity?

Answer 73

Histamine, glutamate, NE

Question 74

How does dopamine effect the CNS? Which disease is caused by decreased dopamine production?

Answer 74

Inhibits motor activity; Parkinson's (overactive motor system)

Question 75

How does acid base balance effect CNS activity?

Answer 75

Acidosis → increased free Ca++ → reduced CNS activity Alkalosis → decreased free Ca++ → increased CNS activity