Skeletal Muscle and Electrmyography

Question 1

Functions of muscle tissue

Answer 1

• moving and stabilizing the skeleton
• pumping blood
• moving food through digestive system
• ## supporting and protecting organs

Question 2

Functions of skeletal muscle tissue

Answer 2

• makes movement
• breathing
• speech
• facial expression
• under voluntary control

Question 3

Definition of Excitability

Answer 3

muscle cells produce action potentials

Question 4

Definition of Contractility

Answer 4

Muscle cells can shorten

Question 5

Definition of Extensibility

Answer 5

muscle cells can be stretched or lengthened

Question 6

Definition of Elasticity

Answer 6

Muscle cells will return to their original length after being stretched

Question 7

what are fascicles?

Answer 7

bundles of muscle fibers

Question 8

What is fascia?

Answer 8

• holds fascicles, blood and nerves together in one unit
• connects to connective tissue to make tendons

Question 9

What is the purpose of tendons?

Answer 9

Anchor muscle tissue to bones

Question 10

What surrounds individual muscle fibers?

Answer 10

Sarcolemma

Question 11

Muscle fibers

Answer 11

• cell membrane (sarcolemma)
• filled with cytoplasm (sarcoplasm)
• Myofibrils within sarcoplasm
• myofibrils are made up of protein strands called myofilaments

Question 12

Sarcoplasmic Reticulum

Answer 12

Sacs and tubes in the sarcoplasm

Full of calcium ions and surround each myofilament

Question 13

Terminal cisternae

Answer 13

large flat sacs at ends of sarcoplasmic reticulum

lie against narrow tubes called transverse tubules

Question 14

What connects the terminal cisternae to the cell surface?

Answer 14

transverse tubules (T-tubules)

Question 15

What happens during action potential with t-tubules?

Answer 15

action potential traveling along sarcolemma travels down tubules and cause sarcoplasmic reticulum to release calcium into sarcoplasm, which causes myofilaments to change shape and contract muscle

Question 16

Types of myofilaments

Answer 16

1. thick filament
2. thin filament
   these slide past each other and shorten muscle cell during contraction

Question 17

What is a sarcomere?

Answer 17

functional unit of a muscle cell and is formed by repeating units of thick and thin filaments

Question 18

Components of thin filament

Answer 18

proteins
- actin: long string of globular proteins and looks like a strand of beads, has active site that allows myosin to bind to its site
- tropomyosin: cover active sites of actin
-troponin: attached to tropomyosin chains and calcium binds causing it to change shape, dragging tropomyosin off active sites and allows myosin heads to bind to active sites and contract muscle

Question 19

Components of thick filament

Answer 19

Mostly made of myosin
the myosin head is hinged and can more back and forth, will pull actin to accomplish muscle contraction

Question 20

What is cross-bridge formation?

Answer 20

when myosin head attaches to active site

Question 21

What is a power stroke?

Answer 21

after cross-bridge formation the myosin head pivots and causes this power stroke, this forces actin filament to slide toward center of sarcomere

Question 22

what is cross-bridge detachment?

Answer 22

energy from breaking ATP to ADP allows myosin to bend back to its starting position

Question 23

How does the cell become relaxed?

Answer 23

calcium ions are pumped back into sarcoplasmic reticulum

Question 24

What is a motor unit?

Answer 24

One motor neuron and all the individual muscle cells it controls

Question 25

What are the important purposes of motor units?

Answer 25

- allow muscles to modulate strength of contraction - protect our muscles against fatigue

Question 26

How many motor units can a muscle contain?

Answer 26

thousands

Question 27

Definition of recruitment

Answer 27

the activation of additional motor neurons to increase muscle strength and force of a contraction

Question 28

What causes central fatigue?

Answer 28

central nervous system and psychological mechanisms that manifest feeling tired

Question 29

What is peripheral fatigue?

Answer 29

problems with the neuromuscular junction between motor nerve and muscle or problems within the cell at sarcomere(calcium or ATP have been used up)

Question 30

Isometric contraction

Answer 30

- muscle can contract, but does not change length - arm is help in a fixed position

Question 31

Eccentric contraction

Answer 31

- muscle contracts, but become longer - arm is being lowered

Question 32

Concentric contraction

Answer 32

- muscle contracts and shortens - arm is being raised

Question 33

Agonist

Answer 33

prime mover, muscle performing the desired action

Question 34

Antagonist

Answer 34

opposing action

Question 35

Flexion

Answer 35

decrease in angle between body parts

Question 36

Extension

Answer 36

increase in angle between body parts

Question 37

Abduction

Answer 37

movement of body part away from midline

Question 38

Adduction

Answer 38

movement of body part towards midline

Question 39

What is the purpose of electromyography(EMG)?

Answer 39

- to examine electrical activity generated by muscles - measures voltage changes that result from action potentials - can identify muscle weakness as the result of neurologic disorders

Question 40

When looking at an electromyogram, what does an increase in altitude mean?

Answer 40

recruitment of muscle fibers and greater action potential firing rates