exam 1 lecture 7 whole muscle regulation

Question 1

Can a muscle fiber increase the number of sarcomeres in series?

Answer 1

yes. can grow more sarcomeres.

Cell can contract more while each sarcomere doesn’t have to as much. Requires more energy. Doesn’t make it stronger just faster. stays in optimal working zone more.

Question 2

___ kind of training leads to:
Increased oxidative capacity though increased mitochondrial numbers
Increased capillaries around the tissue to supply blood
Conversion of fast glycolytic fibers to fast oxidative fibers

Answer 2

aerobic

Question 3

___ training will lead to
Increased glycolytic capacity through increased storage of glycogen
Increased fiber diameter (satellite cells triggered to form more myofibrils in parallel)

Answer 3

anaerobic (without oxygen)

Question 4

Also, evidence suggests that resistance training strengthens muscles by increasing the number of ___ in motor unit recruitment

Answer 4

synchronization

Question 5

what cells are used to increase muscle fiber diameter and how?

Answer 5

satellite cells form more myofibrils in parallel in response to anaerobic training

satellite cells make more nuclei

Question 6

Hypertrophy is mediated by satellite cells, which can be activated by:

Answer 6

Myogenic pathways

Growth hormone, testosterone, cytokines, IGF

Muscle stress/tension, damage

Question 7

•satellite cells fuse with muscle fiber increasing the number of ___ within the fiber

Answer 7

nuclei

Question 8

how do you think increasing the number of nuclei impacts cell size and functionality?

Answer 8

increase transcription- increases translation of parts that make up myofibrils →

gets bigger, more myofibrils, becomes stronger faster

Question 9

___ is a motor nerve and all the fibers it innervates

Answer 9

motor unit

Question 10

a single muscle fiber can be innervated by more than one neuron. True or False?

Answer 10

false

one fiber = one neuron

(each neuron can innervate many muscle fibers)

Question 11

•Muscle fibers within a motor unit contract ___ upon motor neuron firing

Answer 11

synchronously

(at the same time- activated simultaneously)

Question 12

Describe recruitment for a muscle

Answer 12

the more fibers it stimulates the stronger the response

a muscle can have multiple motor units fire at the same time and creates a bigger response

Question 13

larger motor units have smaller motor neurons. True or False?

Answer 13

false

larger motor units have larger(thicker) motor neurons and more muscle fibers associated with it.

Larger motor units are also stronger than smaller motor units

Question 14

The larger the motor neuron, the more difficult it is to reach ___ (not to be confused with the relationship between axon diameter and speed of AP propagation)

Answer 14

threshold

thicker axon = faster signal but also thicker axon = harder to get to threshold. (get it going)

Question 15

a motor unit is comprised of only one type of ___

Answer 15

muscle fiber

either all slow oxidative or fast oxidative or fast glycolytic

will not have a combo

Question 16

slow oxidative muscle fibers have ___ motor units and are recruited ___.

Answer 16

smaller

first

Question 17

fast oxidative muscle fibers have what size motor units and when are the recruited?

Answer 17

intermediate and second

• Slow oxidative–Smaller motor units–Recruited first
• Fast oxidative–Intermediate motor units–Recruited second
• Fast glycolytic –Larger motor units–Usually only recruited during intense exercise

Question 18

Which muscle fiber type has the largest motor unit and is recruited last only during intense exercise?

Answer 18

Fast glycolytic

• Slow oxidative–Smaller motor units–Recruited first
• Fast oxidative–Intermediate motor units–Recruited second
• Fast glycolytic –Larger motor units–Usually only recruited during intense exercise

Question 19

three places proprioceptors are found to help to refine movement and protect muscle from injury

Answer 19

muscle spindle

golgi tendon organ

joint receptor

Question 20

Muscle spindle fibers respond to ___

Answer 20

stretch

Question 21

the muscle fibers within the muscle spindles are called

Answer 21

intrafusal fibers

Question 22

the muscle fibers outside the muscle spindle are called

Answer 22

extrafusal fibers

Question 23

Muscle ___ provide feedback to the brain about muscle length

Answer 23

spindles

(too stretched not stretched)

Question 24

extrafusal fibers are innervated by what kind of neuron?

Answer 24

alpha motor neuron

Question 25

intrafusal fibers are innervated by what kind of neuron?

Answer 25

gamma neuron

Question 26

what are the blue lines

Answer 26

sensory neuron that carries info back to the brain about how stretched or contracted the muscle is

Question 27

how do the sensory neurons within the muscle spindle work

Answer 27

**frequency of impulse determines position of muscle** if muscle stretched sends more action potentials to the brain if muscle contracted action potentials decrease in frequency **gamma motor unit keeps the sensory fibers contracted during contraction- keeps the fibers aware of what is happening**

Question 28

how can a muscle fiber tell if it a lot contracted or a little contracted

Answer 28

the alpha subunit contract the outside fibers ## Footnote **gamma contracts the fibers within the muscle spindle- keeps the sensitivity high**

Question 29

explain stretch reflex

Answer 29

hit tendon, “stretches the muscle.” Muscle spindle sends message to CNS “ we are stretching, could be too stretched” reflex- skips the brain, goes into the spinal cord and right back out and inhibits antagonistic muscles which makes them relax and original muscle to contract → kick leg

Question 30

golgi tendon organs respond to ___ in muscle tension

Answer 30

increases

Question 31

activation of golgi tendon organs causes ___ signals to the motor neuron

Answer 31

inhibitory

Question 32

what sense organs are used to prevent over contraction

Answer 32

Golgi tendon organs example- someone throws something really heavy, you immediately drop it

Question 33

golgi tendon organs will send a signal to inhibit ___ and activate \_\_\_

Answer 33

flexor muscles (original muscle that is being contracted) extensor muscle (muscle opposite to first muscle ex. someone throughs something , you immediately drop it

Question 34

Answer 34

withdrawal and crossed extensor reflex step on something causes left and pull back of the leg

Question 35

slow twitch type 1 muscle fiber, motor unit, motor neuron

Answer 35

Question 36

fast twitch Type IIa chart

Answer 36

Question 37

Fast twitch type IIb chart

Answer 37

Question 38

compare skeletal to smooth muscle

Answer 38

Question 39

compare skeletal, smooth and cardiac muscle

Answer 39