skeletal muscle

Question 1

How is the movement of a joint accomplished?

Answer 1

Internal forces initiated by muscle fibers are transmitted across connective tissue to the tendon causing the movement of the skeleton

Question 2

Epimysium

Answer 2

outermost layer of connective tissue covering the muscle

Question 3

Endomysium

Answer 3

connective tissue covering each muscle fiber cell

Question 4

sarcolemma

Answer 4

has junctional folds in the innervation zone where action potentials are transmitted

Question 5

transverse tubules

Answer 5

extend laterally through fiber to allow impulses to reach all myofibrils

Question 6

Sarcoplasmic reticulum

Answer 6

tubules paralleling myofilaments; store Ca+ which is essential for control of contraction

Question 7

myofibrils

Answer 7

fine protein filaments that contain contractile elements

Question 8

Sarcomere

Answer 8

the smallest functional unit of a muscle

Question 9

Myosin (thick) filament

Answer 9

contains 2 protein strands that form globular heads that attach to actin

Question 10

actin ( thin) filament

Answer 10

composed of mostly actin but tropomyosin and troponin as well

Question 11

what proteins are responsible for cross-bridging?

Answer 11

actin and myosin

Question 12

What’s in the I-band?

Answer 12

thin filamments only

Question 13

What’s in the A-band?

Answer 13

thin and thick filaments

Question 14

What’s in the H-band?

Answer 14

thick filaments

Question 15

what is the excitation component of excitation-contraction coupling?

Answer 15

electrical impulse initiated by a motor neuron propagates to fibers and initiates contraction

Question 16

what happens when an electrical signal is transmitted?

Answer 16

It transferred to a chemical signal of neuromuscular function

Question 17

what happens in excitation-contraction coupling?

Answer 17

1. When ACh is received by the receptors, action potential is transmitted to the muscle
2. The action potential then goes down the T-tubules and causes the release of calcium to be released into the sarcoplasm
3. The calcium ions then bind to troponin which moves the tropomyosin

Question 18

why do muscle fibers shorten?

Answer 18

the cross Bridging occurs when the myosin heads detaches, tilt its head, and reattaches

Question 19

what is power stroke?

Answer 19

the tilting of myosin head from 90 degrees to 45 degrees

Question 20

what is the sliding filament theory?

Answer 20

the repeated actions of the attachment of the myosin head and the power stroking

Question 21

how does cross-bridging relate to force?

Answer 21

the more cross-bridging cycling happens, the more force is generated. Larger muscles have alot more sarcomeres making more cross-bridging cycles.

Question 22

what is needed for the sliding filament theory?

Answer 22

ATP is needed for the sliding filament theory. it binds to myosin during myosin-actin attachment.

Question 23

Type I muscle fibers

Answer 23

• slow twitch
• slow oxidative
• contractile speed = slow
• fatigue resistance = high
• motor unit strength = low

Question 24

Type II muscle fibers

Answer 24

• fast twitch
• oxidative compacity = low
• contractile speed = fast
• fatigue resistance = low
• motor unit strength = high

Question 25

Why do type II muscle fibers have a faster twitch?

Answer 25

Type 2 has a faster twitch because APase works more creating faster contractions, and a more developed SR causing Ca+ delivery to be enhanced