Spinal Reflex

Question 1

What are the 4 main things the spinal cord reflex can do?

Answer 1

1-maintain walking movements
2-withdraw portions of the body from noxious stimuli
3-maintain posture through tone in the legs
4-regulate local blood vessels, GI movements and urinary excretion

Question 2

What are the 5 components of the reflex arc?

Answer 2

1-receptor
2-sensory neuron
3-inegration center (interneuron)
4-motor neurons
5-effector

Question 3

roughly ________ of all nerve fibers running along the spinal cord are propriospinal (connect segments of spinal cord)

Answer 3

half

Question 4

what are the two main structures that sense muscle/tendon stretch/length?

Answer 4

• muscle spindle (in muscle belly)

- golgi tendon organ (ends of muscles/tendons)

Question 5

What modulates the signal before it reaches a motor neuron?

Answer 5

interneurons

Question 6

An example of an interneuron that inhibits surrounding cells to help isolate or sharpen a signal is called?

Answer 6

Renshaw cells

Question 7

What is a motor unit?

Answer 7

single motor neuron and the muscle cells it synapses

Question 8

what are the two types of motor fibers?

Answer 8

1- alpha motor neurons (larger) innervating skeletal muscle

2- gamma motor neurons (smaller) inntervating intrfusal fibers of muscle spindle

Question 9

A reflex with no interneurons (sensory directly synapses motor) is called what?

Answer 9

monosynaptic reflex

Question 10

A reflex with interneurons between the sensory and motor neurons is called what?

Answer 10

polysynaptic. allows for modulation of the reflex

Question 11

What is a good example of a monosynaptic reflex?

Answer 11

stretch reflex (knee jerk reaction)

Question 12

alpha and gamma fiber coactivation helps coordinate what?

Answer 12

relaxation or contraction of a muscle spindle to help maintain its relatively length to the muscle (allows for tone of the muscle)

Question 13

Golgi tendon organ reflex is a good example of what?

Answer 13

polysynaptic reflex allowing the muscle to rapidly lengthen if it is stretched

Question 14

Retracting the limb exposed to a noxious stimulus and extending the other to push away is which reflex?

Answer 14

Flexor and crossed extensor reflex (stepping on a tack and hoping to the other leg for support. can be suppressed by consciously modulating interneurons)