Motor Unit Continued

Question 1

What are the 3 layers of connective tissue and what are they connected to?

Answer 1

muscle –> epimysium
fascicle –> perimysium
fiber –> endomysium

Question 2

Why do we need so many nuclei in these cylinders?

Answer 2

to use lots of protein

Question 3

What is the sarcomere? What’s in them?

Answer 3

where muscle contraction happens

myosin (thick) filament and actin (thin) filament

Question 4

What does tropomyosin do? What is troponin?

Answer 4

Tropomyosin prevents myosin and actin from interacting

Troponin moves tropomyosin through calcium, allowing a myosin head to attach from a myosin filament

Question 5

What are the steps for muscle contraction and relaxation involving Ca2?

Answer 5

Contraction
1. muscle action propagated
2. Ca2 released, binds to troponin, removing tropomyosin

Relaxation
1. Ca2 removal restores tropomyosin
2. Ca2 taken up and relaxation

Question 6

What is force regulation dependent on? And what are they called?

Answer 6

1. type of and number of fibers recruited (stimulus strength)
2. nature of neural stimulation (stimulus frequency)
3. initial length of muscle at time of contraction

Question 7

What does strength coding determine?

Answer 7

number of motor units recruited and their size

Question 8

What does frequency coding determine?

Answer 8

how often a single pool of fibers contracts

how powerfully a single pool of fiber contracts

figuring out lengths and correlation with force

Question 9

What determines the fiber type?

Answer 9

the neuron and its size (bigger the faster)