Exam 3

Question 1

closed-loop control mechanisms maximize accuracy

Answer 1

information from whatever is being closed flows back to the device that controls it

Question 2

open-loop control mechanisms maximize speed

Answer 2

there are no external forms of feedback and the activity is preprogrammed

Question 3

What ion increases muscle contraction?

Answer 3

calcium

Question 4

where do motor neurons synapse onto skeletal muscle cells

Answer 4

the NMJ

Question 5

what initiates muscle contractions?

Answer 5

motor neurons that synapse onto muscle fibers

Question 6

where are afferent sensory neurons found?

Answer 6

dorsal root

Question 7

where are cell bodies of efferent motor neurons found?

Answer 7

ventral horn

Question 8

where do motor neurons exit the spinal cord to control the muscles?

Answer 8

ventral root

Question 9

lower motor neurons/alpha motor neurons

Answer 9

lower motor neurons from the ventral horn innervate skeletal muscle fibers at the NMJ (specifically the main extrafusal fibers). Lower motor neurons control muscle contraction.

Question 10

motor unit

Answer 10

motor neuron and all of the muscle fibers it innervates

Question 11

muscle spindle

Answer 11

muscle receptor that sends action potentials to the CNS when the muscle is stretched. it contains intrafusal fibers – the muscle fibers outside the muscle spindle are extrafusal fibers

Question 12

how does a spindle neuron send information back to the CNS

Answer 12

it wraps around the intrafusal fiber and sends signals to the spinal cord through 1a fibers

Question 13

what do alpha motor neurons that innervate the intrafusal muscle fibers do?

Answer 13

cause the muscle spindle to shorten, which modifies its sensitivity to changes in length of extrafusal fibers, thereby allowing the spindle to function at all muscle lengths

Question 14

Golgi tendon

Answer 14

One of the tendon receptors that sends action potentials back to CNS about large loads and muscle tension

Question 15

Afferent Ib sensory neurons

Answer 15

send info from golgi tendon back to CNS

Question 16

upper motor neurons

Answer 16

large efferent pyramidal neurons found primarily in Layer V of M1 that send their axons to the brainstem and spinal cord for control of voluntary movements

Question 17

SMA

Answer 17

Plans movements that are internally generated. Receives input from the basal ganglia and premotor cortex and modulates the activity of M1. Fires during mental rehearsal.

Question 18

what comes from bilateral damage to the SMA

Answer 18

trouble forming a motor plan (apraxia)

Question 19

Premotor cortex

Answer 19

Directs movements in response to external cues. Combines information from prefrontal cortex and posterior parietal cortex. Helps select proper combination of primary afferent neurons.

Question 20

what connects the cerebellum to the CNS

Answer 20

cerebellar peduncles

Question 21

output from cerebellum is through

Answer 21

Purkinje cell axons which project to deep cerebellar nuclei. Purkinje cells produce inhibitory action potentials (GABA), so the cerebellum guides movement by inhibiting neurons.

Question 22

main region for inputs to the basal ganglia

Answer 22

striatum (caudate nucleus + putamen)

Question 23

what damages upper motor neurons?

Answer 23

Stroke/trauma/tumors. Results in hypertonia and hyperreflexia – loss of inhibitory modulation from descending pathways results in lower motor neuron firing, so more uncontrolled reflexes and stiff muscles.

Question 24

ideational apraxia

Answer 24

can perform each part of a movement but not the complete sequence

Question 25

ideomotor apraxia

Answer 25

can’t do movement on command but can do it spontaneously

Question 26

as lower motor neurons die, muscles atrophy and result in

Answer 26

muscle weakness (paresis) fasciculations (muscle fiber twitches) hypotonia (loss of muscle tone) hyporeflexia (lack of reflexes

Question 27

what do the primary and secondary afferent fibers of motor spindles do?

Answer 27

send info on length & stretch to CNS

Question 28

The partial paralysis caused by damage to primary motor cortex is called

Answer 28

paresis

Question 29

what do gamma motor neurons do?

Answer 29

send action potentials to stimulate the intrafusal to correct its length (otherwise you would have no idea that your muscles were holding a load)

Question 30

basal ganglia plays a role in determining the

Answer 30

amplitude and direction of movement

Question 31

during REM, thermoregulation is

Answer 31

impaired

Question 32

NREM aids in the consolidation of

Answer 32

declarative memories

Question 33

what kind of neurons make up the striatum?

Answer 33

inhibitory medium spiny neurons

Question 34

damage to the basal ganglia causes what symptom of Parkinson's?

Answer 34

it slows movement

Question 35

deterioration of the basal ganglia causes what symptom of Huntington's?

Answer 35

excessive movement