Exam 4

Question 1

What are alpha motor neurons?

Answer 1

Neurons that send signals from the spinal cord to muscle fibers, directly triggering muscle contractions

Question 2

What is a motor unit?

Answer 2

It’s a single alpha motor neuron and all the muscle fibers it controls (A coach and it players)

Question 3

What is a motor neuron pool?

Answer 3

A group of alpha motor neurons that innervate a single muscle, collectively coordinating its movements (Lots of coaches for one player)

Question 4

What are the major differences between slow and fast motor units?

Answer 4

Slow Motor Units contract slowly and are more useful for endurance purposes
Fast Motor Units contract quickly producing high force for brief periods

Question 5

What is Excitation–Contraction Coupling?

Answer 5

It’s the process in which a muscle receives a signal to move and then actually does the movement.

Question 6

What is the Sarcolemma?

Answer 6

The outer layer or “skin” of a muscle cell. (helps pass the signals into the muscle cell)

Question 7

What are Myofibrils?

Answer 7

They are tiny fibers in a muscle cell that shorten when a muscle retracts (Made of sarcomeres)

Question 8

What is the Sarcoplasmic Reticulum?

Answer 8

It’s a specialized form of the endoplasmic reticulum in muscle cells that stores and releases calcium ions

Question 9

What are T-Tubles?

Answer 9

These are tunnel-like extensions of the sarcolemma that go deep into the muscle fiber. They help transmit electrical signals to all parts of the muscle fiber.

Question 10

What is a sarcomere?

Answer 10

The sarcomere is the basic contractile unit of muscle.

Question 11

What is the difference between thick and thin filaments?

Answer 11

Thick filaments: Made of Myosin, Pull the thin filaments to shorten the sarcomere
Thin filaments: Made of the actin, pulled in by the myosin head of the thick filament

Question 12

What are muscle spindles?

Answer 12

These are sensory receptors within muscles that detect changes in muscle length.

Question 13

What is proprioception?

Answer 13

This is the body’s ability to sense its position and movement in space.

Question 14

What is the stretch reflex?

Answer 14

It is a reflex in which if you stretch a muscle too fast the muscle will automatically contract to counteract and prevent injury

Question 15

What are gamma motor neurons?

Answer 15

These neurons control the sensitivity of muscle spindles. (They ensure that proprioceptive feedback is accurate during muscle contractions)

Question 16

What is the Golgi Tendon Organ?

Answer 16

Located at the junction of muscles and tendons, they detect tension in the muscle and send signals to the brain when excessive force is detected to prevent muscle damage

Question 17

What is Reciprocal Inhibition and how does it affect muscle coordination?

Answer 17

This is the process by which muscles on one side of a joint relax to allow muscles on the other side to contract.

Question 18

What are Central Pattern Generators (CPGs)?

Answer 18

They are neural circuits within the spinal cord that produce rhythmic movements, like walking or breathing, without needing conscious thought.

Question 19

What are the two main motor pathways?

Answer 19

The Lateral pathway and the Ventromedial pathway

Question 20

What is the lateral pathway?

Answer 20

A group of nerve pathways in the spinal cord that help control precise, VOLUNTARY movements, especially in the distal areas of the body. (Feet and Hands)

Question 21

What is the Ventromedial pathway?

Answer 21

Another set of spinal pathways, that controls posture and balance by affecting muscles closer to the body’s center, like those in the back and trunk. (Proximal/Axial)

Question 22

What is the Corticospinal tract?

Answer 22

A spinal cord pathway that carries movement signals from the brain’s motor cortex to the spinal cord, helping control fine motor movements. (Lateral cortiospinal tract crosses at the medulla)

Question 23

What is the Rubrospinal tract?

Answer 23

A pathway that starts in the red nucleus of the brain and helps with voluntary control of big muscles (Can act as a backup if the Corticospinal tract is injured)

Question 24

What is the red nucleus?

Answer 24

A part of the brainstem that acts as a relay center for motor signals, especially those involving movement and coordination of the arms.

Question 25

What is the Vestibulospinal tract?

Answer 25

A pathway that helps keep balance and posture by sending signals from the inner ear

Question 26

What is the Tectospinal tract

Answer 26

A pathway that helps coordinate head and neck movements, especially in response to visual or auditory stimuli

Question 27

What is the Reticular formation?

Answer 27

A network of neurons in the brainstem that plays a role in alertness, but also helps control muscle tone and some reflexes.

Question 28

What is the Pontine reticulospinal tract? (From the Pons)

Answer 28

It’s part of the reticular formation pathway that helps maintain posture and muscle tone.

Question 29

What is the Medullary reticulospinal tract? (From the Medulla)

Answer 29

It’s part of the reticular formation pathway that helps relax muscles so movements are smoother.

Question 30

What is the difference between low motor neurons and upper motor neurons?

Answer 30

LMN: Found in the spinal cord, they receive signals from UMNs and transmit those signals to muscle fibers
UMN: Found in the motor cortex, sends signals to LMNs and
are responsible for initiating and planning voluntary movement

Question 31

What is the purpose of the Premotor Area (PMA)?

Answer 31

The PMA is involved in planning movements and coordinating movements in response to external cues, like seeing a target to reach for.

Question 32

What is the purpose of the Supplementary Motor Area (SMA)?

Answer 32

The SMA helps with planning and coordinating more complex sequences of movements, often involving both sides of the body, such as clapping.

Question 33

What is special about mirror neurons?

Answer 33

They activate both when you perform an action and when you see someone else performing the same action, like grasping an object.

Question 34

What is the Ventral Lateral Nucleus (VLN)?

Answer 34

A region in the thalamus that relays motor information from the cerebellum and basal ganglia to the motor cortex

Question 35

What is the striatum?

Answer 35

The input region of the basal ganglia (Made of the Caudate Nucleus and Putamen)

Question 36

What are the two different pathways Imputs to the striatum can go through?

Answer 36

The direct pathway (The short one) and the indirect pathway.

Question 37

What are MSNs? What are the two types?

Answer 37

Medium spiny neurons. They are both dopamine receptors where one expresses dopamine D1 receptors and one expresses dopamine D2.

Question 38

Explain the direct pathway.

Answer 38

Excitatory synapses come into the striatum to target (MSNs)
D1 MSNs are then activated and inhibit Globus Pallidus internal or (GPI) which project to and inhibits the VLN
-NET EXCITATORY

Question 39

Explain the indirect pathway.

Answer 39

Excitatory synapses come into the striatum to target (MSNs)
D2 MSNs are then activated and inhibit Globus Pallidus external which inhibits Globus Pallidus internal which project to and inhibits the VLN (Can also use the Subthalamic Nucleus)
-NET INHIBITORY

Question 40

What structure in the basal ganglia helps decide which pathway dominates and plays a significant role in learning?

Answer 40

The “Substantia Nigra pars compacta” are dopamine neurons that synapse at all portions of the striatum to release dopamine onto MSNs (Excites the D1 neurons, inhibits the D2 neurons)

Question 41

What is different about the eye movement pathway of the basal ganglia?

Answer 41

The pathway is identical until it replaces the VLN with the Substantia Nigra pars reticulata which then affects eye movements through the superior colliculus

Question 42

What is Parkinson’s disease?

Answer 42

A neurodegenerative disorder due to the loss of dopamine-producing cells in the substantia nigra.

Question 43

What are common symptoms of damage to upper motor neurons?

Answer 43

-Loss of voluntary movement (Retention of reflexes)
-Increased reflexes
-Clonus/hypertonia (Rhythmic, repetitive muscle contractions)
-

Question 44

What are common symptoms of damage to lower motor neurons?

Answer 44

-Flaccid paralysis
-Decreased reflexes
-Severe muscle atrophy (due to not using them)