exam two (ch. 13)

Question 1

motor neurons located in the ventral horn of spinal cord and sends axons through the ventral root

Answer 1

lower motor neurons

Question 2

what motor neurons directly trigger muscles to contract

Answer 2

alpha motor neurons

Question 3

alpha motor neurons in charge of proprioception

Answer 3

gamma motor neurons

Question 4

know steps of excitation contraction coupling and sliding filament model

Question 5

a single action potential leads to a muscle twitch and the summation of them leads to

Answer 5

contraction

Question 6

greatest frequency of action potentials =

Answer 6

smoothest contraction

Question 7

there are two types of white muscle fibers

Answer 7

fast fatigable and fatigue resistant

Question 8

white muscle fibers are found in fast motor units such as

Answer 8

fight or flight responses

Question 9

red muscle fibers contain many ______ and contract and fatigue _____

Answer 9

mitochondria; slowly

Question 10

motor neurons in the ventral horn controlling flexors lie ___ to those controlling extensors

Answer 10

dorsal

Question 11

motor neurons in the ventral horn controlling axial muscles lie ____ to those controlling distal muscles

Answer 11

medial

Question 12

what are three inputs to alpha motor neurons

Answer 12

1. upper motor neurons
2. proprioceptive input from muscle spindles
3. spinal interneurons (excitatory or inhibitory)

Question 13

what controls the motor neuron in the spinal cord (proprioceptive control)

Answer 13

sensory (proprioceptive) feedback from muscle spindles and stretch receptors in muscle fiber

Question 14

the sensory proprioceptive signal is carried by __ ______sensory axon

Answer 14

a alpha (large and myelinated)

Question 15

the stretch reflex is a ____ feedback loop

Answer 15

monosynaptic

Question 16

the discharge rate of A alpha Ia sensory axon depends on ____ of the stretched muscle

Answer 16

length

Question 17

the ___ motor neuron is needed to maintain the myotatic stretch reflex

Answer 17

gamma

Question 18

the gamma motor neuron changes set point of the stretch reflex and keeps tension on ___ ____

Answer 18

intrafusal fibers

Question 19

the ___ ____ ___ is located at the junction of muscle and tendon; monitors muscle tension

Answer 19

golgi tendon organ

Question 20

the activation of Ib (alpha a) sensory axon by the golgi tendon organ excites an _____ interneuon which in turn inhibits what?

Answer 20

inhibitory; alpha motor neuron (reducing force of contraction)

Question 21

the proprioceptive axons in joint tissues respond to what kind of movement

Answer 21

angle, direction, velocity

Question 22

contraction of one muscle accompanied by relaxation of antagonist muscle is called

Answer 22

reciprocal inhibition

Question 23

myotatic reflec in arm: contraction of biceps muscle is ____ and relaxation of triceps is ____ because of an ___ ____

Answer 23

monosynaptic, polysynaptic , inhibitory interneuron

Question 24

flexor withdraw reflex

Answer 24

Step on tack
2. Activate Aδ (pain) axon
3. Pain axon activates
excitatory interneurons
in adjacent segments of
spinal cord
4. Interneurons activate
alpha motor neurons
innervating flexor
muscles (not shown –
extensor muscles on that
side would need to relax)

Question 25

when you have the flexor withdrawl reflex you dont fall over because of the ___ ____ ___

Answer 25

crossed extensor reflex

Question 26

the crossed extensor reflex involves both inhibitory and excitatory interneurons; one of which _____

Answer 26

crosses

Question 27

spinal motor programs for walking require __ ___ ____

Answer 27

central pattern generator

Question 28

know proccess of rhytmic activity in spinal interneuron

Question 29

walking without thinking requires continuous excitatory input from ___ ___ and input from both excitatory and inhibitory motor neurons

Answer 29

motor cortex

Question 30

primary efferent neurons enter via the vertebral colummn via the ____ root

Answer 30

dorsal

Question 31

four types of primary afferent neurons

Answer 31

A alpha, A beta, A delta, C