Bio 334 Exam 2 Lec 8 Movement, Motor Units, Reflex Circuits

Front 1

We have a nervous system in order to...

Back 1

Move! Movement is the key to finding a place to live, eat and reproduce successfully.

Front 2

Describe Tunicate's life cycle

Back 2

Start out as larvae that swim and have a nervous system. They attach to a good rock and become sessile. When sessile they digest almost entire nervous and sensory system and turn into a giant gut.

Front 3

Voluntary Movement

Back 3

involves the entire brain. Sensory and Motor.

Front 4

Attention

Back 4

A neural process by which you enhance your perception of certain
stimuli relative to other stimuli in the environment.

Front 5

Parts of the Brain important for Attention

Back 5

Parietal and Frontal Cortex

Front 6

The nervous system plans its movements in terms of...

Back 6

its goal rather than the motor system
used to accomplish the task.

Front 7

Our brain transforms joint coordinates into

Back 7

Cartesian coordinates in order to move to a point in the real world. Converting between different coordinate systems introduces some distortion.

Front 8

Your body must set _____ degrees of freedom.

Back 8

6 total degrees of freedom.

3 degrees of freedom specify the translational components of the goal.

3 degrees of freedom specify the rotational components of the goal

Front 9

Shoulder has how many degrees of freedom?

Back 9

4 degrees of freedom

Front 10

Elbow has how many degrees of freedom?

Back 10

2 degrees of freedome

Front 11

Wrist has how many degrees of freedom?

Back 11

2 degrees of freedom

Front 12

Fingers have how many degrees of freedom?

Back 12

at least 2 degrees of freedom

Front 13

You need at least how many degrees of freedom to specify a 6 degree of freedom movement goal like moving your arm?

Back 13

10 total

2 for fingers + 2 for wrist + 2 for elbow + 4 for shoulder

Front 14

What is the advantage of excess degrees of freedom?

Back 14

Ability to go around obstacles. You have multiple ways to reach the same location in space.

Front 15

Why adjust your posture before moving?

Back 15

The body's center of gravity is the point where all forces acting on the body are balanced. When you reach out, that center shifts. Therefore you would need to contract your back and leg muscles before reaching out.

Front 16

Your brain estimates the weight of an object before or after you catch it?

Back 16

Before.

Front 17

Movement begins in the brain in several places at about the same time. This is a ___ process.

Back 17

Movement is a parallel process.

Front 18

Parts of the brain where movement begins are?

Back 18

Motor Cortex, Basal Ganglia and Cerebellum

Front 19

Proprioception

Back 19

compares the actual movement with the expected movement aka the brain's model of the movement

Front 20

Sensation during movement is...

Back 20

the difference between expected sensory consequences of a movement and the actual sensory signals from the movement.

Front 21

Brain is only interested in ____ sensory signals from movement.

Back 21

unexpected sensory signals

Front 22

Reflexes

Back 22

involuntary coordinated patterns of muscle contraction and relaxation elicited by peripheral stimuli

Front 23

Rhythmic Motor Patterns

Back 23

repetitive patterns of movement like running, swimming, breathing that are produced by rhythmic neural circuits aka central pattern generators

Front 24

Voluntary Movements

Back 24

movement initiated internally

Front 25

Nervous system controls muscles through..

Back 25

1. muscle control through motor units and motoneurons
2. Muscle excitation contraction coupling
3. characterizing motor units

Front 26

Exciting alpha motoneurons activates...

Back 26

motor units

Front 27

Motor unit

Back 27

one alpha-motoneuron and all of the muscle fibers that it innervates

Front 28

Each muscle consists of...

Back 28

thousands of individual muscle fibers

Front 29

Each muscle fiber receives input from...

Back 29

only one alpha-motoneuron.

Front 30

Each alpha-motoneuron innervates

Back 30

many muscle fibers

Front 31

Motor neuron pool

Back 31

all the alpha-motoneurons that innervate one muscle

Front 32

alpha-motoneurons are in the ___spinal cord

Back 32

ventral spinal cord aka ventral horn

Front 33

alpha-motoneurons in the ventral horn in the cervical enlargement (also known as the spinal segments C3 to T1) control...

Back 33

arm and shoulder

Front 34

alpha-motoneurons in the ventral horn of the lumbar enlargement (also known as spinal segments L1 to S3) control...

Back 34

the legs

Front 35

describe how alpha-motoneurons make muscles contract. describe the neuromuscular junction

Back 35

1. action potential travels down the axon and depolarizes the presynaptic membrane.
2. Depolarization leads to vesicle fusion and release of acetylcholine also called ACh.
3. ACh binds to ACh receptors in the muscle membrane. The binding opens a cation channel that allows sodium influx and potassium efflux that will depolarize the muscle.
4. Membrane bound acetylcholinesterase (AChase) breaks down ACh therefore removing ACh from the synaptic cleft.

Front 36

What does ACh do?

Back 36

binds to ACh receptors in muscle membrane which opens cation channel allowing sodium influx and potassium outflow thereby depolarizing membrane.

Front 37

What is Myasthenia Gravis?

Back 37

disease that disrupts the neuromuscular junction. It occurs when antibodies develop to your own ACh receptors. Symptoms include waxing and waning weakness and tiredness.

Front 38

What's a sarcomere?

Back 38

fundamental unit of muscle fiber contraction

Front 39

Sliding-Filament Hypothesis

Back 39

Calcium entry into the myofibril enables the thin filaments (actin) to slide along the thick filaments (myosin). This generates force.

Front 40

When calcium binds to troponin...

Back 40

troponin undergoes a conformational change that shifts tropomyosin to unblock myosin binding sites on the actin

Front 41

myosin binding sites are on...

Back 41

actin (thin filaments)

Front 42

What does myosin binding do?

Back 42

1. Myosin heads with bound ATP release the actin.
2. The binding of the myosin to the actin creates an ATPase that releases a phosphate.
3. The energy released from turning ATP to ADP causes myosin head to bend which moves the actin. Once ADP is release the myosin and actin bond is very stable.

Front 43

alpha-motoneuron action potential produces..

Back 43

a motor unit twitch

Front 44

twitches are characterized by...

Back 44

1. size of twitch
2. twitch speed, time to peak force in milliseconds
3. Half relaxation time aka the time from peak force until force falls by half

Front 45

what affects muscle twitch?

Back 45

the number of actin-myosin bonds determines twitch force

Front 46

Describe the relationship between contractile force of a muscle and its length.

Back 46

when muscle overly stretched with no overlap, no force is generated. when muscle length very short so actin filaments overlap and myosin begins to run into z-line, there is very little muscle force. Maximum force is at resting length

Front 47

Muscle resting length

Back 47

When the overlap of myosin and actin is nearly complete and the muscle has maximum contraction force at that length.

Front 48

Cross Bridge Formation

Back 48

a function of calcium concentration

Front 49

Latent Period

Back 49

A delay caused by the time required for fast calcium release, passive diffusion of calcium to the myofibrils, activation of actin, cross bridge formation, and stretching of elastic elements

Front 50

Back 50

muscle force as related to calcium release from an action potential and then active rapid reuptake that decreases the number of cross bridges reducing muscle force.

Front 51

Calcium release from a single action potential is only sufficient to activate ....

Back 51

a small number of cross bridges.

Front 52

Describe tetanus in terms of action potentials

Back 52

a high frequency grouping of action potentials that affects a motor unit and produces maximal force

Front 53

Ways to increase force

Back 53

provide repetitive stimuli aka low-frequency action potentials

Front 54

Tetanus is characterized by

Back 54

1. Fusion frequency which is the frequency of action potentials that are required to produce maximum force at tetanus.
2. Maximum Force which is the force generated at fusion frequency.
3. Fatigabilty which is how long a motor unit can maintain its max force with fusion frequency stimulation

Front 55

Muscle force summates when..

Back 55

Muscle force summates when a second action potential occurs before the muscle has completely relaxed from the first action potential.

Front 56

what does an action potential do?

Back 56

Travels down the axon and depolarizes the presynaptic membrane.

Front 57

Types of motor units

Back 57

slow oxiodative type 1 (slow)
fast oxidative type 2a (fast fatigue resistant)
fast glycolytic type 2b (fast fatigable)

Front 58

Each muscle usually contains all or only one type of motor unit?

Back 58

All

Front 59

Size Principle

Back 59

Nervous system recruits motor units in order of force they generate.

Front 60

Order of Motor Unit Recruitment

Back 60

Slow units first, then fast fatigue resistant, then fast fatigable.

Front 61

Muscle fibers change phenotype (myosin that they express) depending on...

Back 61

pattern of motoneuron input they receive. neural activity of alpha-motoneurons creates change in gene expression. conversely factors expressed by muscles affect expression of motoneuron genes

Front 62

Smaller motoneurons innervate fewer muscle fibers than a large motoneuron so that....

Back 62

motor units controlled by small motoneurons produce less force than motor units innervated by larger motorneurons.

Front 63

Voltage threshold in motoneurons

Back 63

All motoneurons have same voltage threshold for evoking action potentials. Even though small ones have higher Resistance.

Front 64

Isotonic (concentric) contraction

Back 64

muscle contracts and shortens

Front 65

Isometric contraction

Back 65

muscle contracts but doesn't change length

Front 66

Eccentric contraction

Back 66

muscle contracts but load forces muscle to length