Physiology Quiz 4 (Reflex Physiology)

Question 0

Purpose of flexor withdrawal reflex

Answer 0

Protect tissue from damage

Minimize damage when you come into contact with damaging stimuli

Question 1

Reflex activity

Answer 1

Predictable, stereo typical response to a specific stimulus

Question 2

Where does the sensory afferent neuron travel to in the flexor withdrawal pathway?

Answer 2

Travels to the spinal cord through the dorsal root ganglia to branch off one way sending sensory info up to the brain, and another way, to synapse upon several interneurons

Question 3

What is the pathway the signal follows from the afferent neuron to the alpha motor neuron activating the hamstrings of the affected leg? (Flexor withdrawal reflex)

Answer 3

Sensory afferent–> excitatory interneuron–> excitatory interneuron–> alpha motor neuron inner acting hamstrings (contracts hamstrings)

Question 4

Pathway the signal follows from the sensory afferent neuron to the quads of the affected leg

Answer 4

Sensory afferent–> excitatory interneuron–> inhibitory interneuron–> alpha motor neuron innervating quads (quad does not contract)

Question 5

Pathway of signal that goes from sensory afferent neuron to quads of unaffected leg (flexor withdrawal reflex)

Answer 5

Sensory afferent–> excitatory interneuron–> excitatory interneuron–> axon crosses to other side of spinal cord–> excitatory interneuron–> alpha motor neuron innervating quads (quads contract)

Question 6

Pathway of signal that goes from sensory afferent neuron to hamstrings of unaffected leg (flexor withdrawal reflex)

Answer 6

Sensory afferent–> excitatory interneuron–> excitatory interneuron–>crosses to other side of spinal cord–> inhibitory interneuron–> alpha motor neuron innervating hamstrings (hamstrings do not contract)

Question 7

Reciprocal inhibition

Answer 7

When one muscle is contracted (hamstrings) the opposite muscle is inhibited (quads). This happens in the flexor withdrawal reflex so that the affected leg is able to bend at the knee and move away from harm.
This process is typical of reflex and voluntary motor activity

Question 8

Crossed extensor component (of flexor withdrawal reflex)

Answer 8

Opposite leg extending as the affected leg is flexing

Question 9

What is the value of the flexor withdrawal reflex?

Answer 9

Protect tissue from damage

Support body weight when one leg is flexing due to nociceptive input

Question 10

What conditions will interfere with the flexor withdrawal reflex?

Answer 10

Neuropathy (happens in diabetes)

Question 11

Myotatic reflex

Answer 11

Skeletal muscle responds to stretch by contracting (muscle spindles)

Question 12

Other names for myotatic reflex

Answer 12

Spindle reflex
Stretch reflex
Deep tendon reflex

Question 13

Spinal level reflex

Answer 13

A reflex that occurs at the spinal cord level

Question 14

Is myotatic reflex a spinal level reflex?

Answer 14

Yes

Question 15

Purpose of myotatic reflex

Answer 15

Keep body upright during postural perturbations (ie, using elevator, uneven terrain)

Question 16

Where are muscle spindles?

Answer 16

Randomly disbursed in muscles

Question 17

What is the only monosynaptic reflex in the body?

Answer 17

Myotatic reflex

Question 18

Are there interneurons in the myotatic reflex?

Answer 18

No

Question 19

Where does the 1a afferent nerve go from the muscle spindle?

Answer 19

To spinal cord via dorsal root ganglion

Question 20

What type of afferent nerve carries info from the muscle spindle to the CNS?

Answer 20

1a

Question 21

Proprioception

Answer 21

Ability to know where body parts are without looking at them

Question 22

What tends to happen to gait in people with diabetes/neuropathy and why?

Answer 22

Either:

1. Steppage gait
2. Watch feet

Happens because proprioception is compromised

Question 23

Steppage gait

Answer 23

Walking with exaggeration of picking up feet

Question 24

How does muscle spindle carry proprioceptive info to brain?

Answer 24

1a afferent nerve branches off after the dorsal root ganglion and goes up to the brain

Question 25

Nerve pathway from muscle spindle to hamstring

Answer 25

1a afferent from spindle--> enters dorsal root ganglion--> inhibitory interneuron--> alpha motor efferent neuron innervating hamstring (inhibits hamstring via reciprocal inhibition)

Question 26

Gamma motor neuron

Answer 26

Smaller than 1a efferents, myelinated

Question 27

Intrafusal fiber

Answer 27

Referring to muscle spindle itself

Question 28

Extrafusal fibers

Answer 28

Standard muscle cells surrounding spindle

Question 29

Function of muscle spindle

Answer 29

Reflex | CNS input about muscle length

Question 30

Where are contractile filaments located on spindle

Answer 30

At tips of spindle (innervating by gamma motor neurons) | None in middle of spindle

Question 31

What increases the firing rate of the 1a afferent is coming from the spindle?

Answer 31

center of the spindle is stretching

Question 32

Alpha-gamma coactivation

Answer 32

Activating both alpha and gamma motor neurons during contraction (happens when you do a contraction)

Question 33

Cerebellum role in muscle contraction/coordination

Answer 33

Makes adjustments in muscle activation based on info from spindles (info about muscle length) -tested by having a patient hold their arms in front of body with elbows bent, therapist pulls forearms away and patient is instructed to resist, therapist let's go...if patient hits self in chest, indicates problem with cerebellum

Question 34

Subunits of spindles

Answer 34

Nuclear bag fibers | Nuclear chain fibers

Question 35

How many subunits of spindle fibers are there?

Answer 35

12-15

Question 36

Nuclear bag fibers AKA

Answer 36

Dynamic fibers

Question 37

Nuclear chain fibers AKA

Answer 37

Static component

Question 38

What are nuclear bag fibers most effective at measuring?

Answer 38

Muscle length as the muscle length changes

Question 39

What is nuclear chain fiber most effective at monitoring?

Answer 39

Muscle length when it is unchanging

Question 40

Can nuclear bag fibers and nuclear chain fibers perform each other's function?

Answer 40

Yup, they are just not as good at it

Question 41

(Nuclear bag/nuclear chain) fibers have lower viscosity

Answer 41

Bag

Question 42

Nuclear (bag/chain) fibers have higher viscosity

Answer 42

Chain

Question 43

Role of gamma motor fibers in spindles

Answer 43

Contract the filaments at the tips of the spindles in synchrony with the extrafusals

Question 44

What is activated by higher motor control centers during voluntary and reflex motor activity?

Answer 44

Alpha and gamma motor neuron

Question 45

What allows the higher motor control centers to monitor muscle length during voluntary and reflex contraction of muscle?

Answer 45

Activation of alpha and gamma motor neurons

Question 46

Gamma bias

Answer 46

Presenting of gamma activity as voluntary motor activity begins

Question 47

What is gamma bias based on?

Answer 47

Prediction by motor centers as to how rapidly and how much muscle length will change with the activity

Question 48

How gamma bias works with higher centers

Answer 48

As information comes in informing motor control centers about what is going on, this is compared to the predictions, and if there is a difference, corrections are made as movement proceeds

Question 49

There is always some level of tone in muscle. What is it maintained by?

Answer 49

Partly maintained by gamma neurons

Question 50

What does constant level of gamma tone allow for?

Answer 50

Constant flow of info about muscle length

Question 51

High tone

Answer 51

Excessive gamma bias

Question 52

Low ton

Answer 52

Abnormally low gamma bias

Question 53

What happens to gamma activity with neurological injury?

Answer 53

Balance between facilitation and inhibition of gamma activity is upset

Question 54

Where are Golgi tendon organs found?

Answer 54

In tendons of all skeletal muscles

Question 55

What des GTO monitor?

Answer 55

Muscle tension

Question 56

What type of afferent nerve carries info from GTO

Answer 56

1b fibers (myelinated, slightly smaller than 1a)

Question 57

Where are the sensory endings located in the GTO

Answer 57

Intertwined among the collagen fibrils

Question 58

How does GTO measure tension?

Answer 58

Muscle contracts | Tension transmitted through collagen fibrils, which stimulates the specialized sensory endings

Question 59

Golgi tendon organ reflex AKA

Answer 59

Inverse Myotatic reflex

Question 60

Function of GTO

Answer 60

Thought to be important in protecting tendons from injury... | Fater's opinion: role is to keep higher motor centers informed about the degree of muscle tension developed

Question 61

Pathway of nerve signal in GTO response

Answer 61

``` Same as flexor withdrawal, except the afferent nerve is a 1b fiber In affected leg: Quads inhibited Hamstrings activated In unaffected leg: Quads activated Hamstrings inhibited ```