Muscle Unit

Question 1

Types of Muscle Cells

Answer 1

• Skeletal (voluntary)
• Smooth
• Cardiac

Question 2

Function of Muscles

Answer 2

1. Produce movement
2. Maintain posture
3. Support soft tissues
4. Protection
5. Maintain body temperature
6. Store nutrient reserves

Question 3

Skeletal

Answer 3

Multinucleated with long large fibers

Question 4

Cardiac

Answer 4

Branch shaped cells with intercalated disks (doesn’t need a nerve to activate)

Question 5

What do muscle fascicles make up?

Answer 5

Skeletal Muscle

Question 6

What do muscle fibers make up?

Answer 6

Muscle fascicle

Question 7

What do myocytes make up?

Answer 7

muscle fibers

Question 8

What do myofibrils make up?

Answer 8

myocytes

Question 9

What makes up the myofibrils?

Answer 9

sacromers

Question 10

What is the thick filament

Answer 10

Myosin

Question 11

What holds myosin in place?

Answer 11

Titin

Question 12

What is the thin filament? What does it do?

Answer 12

Actin ; it pulls myosin together

Question 13

Tropmyosin

Answer 13

prevent the muscle from contracting at the wrong time

Question 14

Troponin

Answer 14

promotes muscle contraction

Question 15

A band

Answer 15

spans length of myosin fiber

Question 16

I band

Answer 16

contains only actin fibers ; no myosin

Question 17

H band

Answer 17

contains myosin fibers ; no actin

Question 18

Z line

Answer 18

acts as anchor for actin fibers

Question 19

M line

Answer 19

middle line (vertical medial line) to hold myosin in place

Question 20

How does fiber shortening happen?

Answer 20

As sarcomeres shorten, muscle pulls together, producing tension

Question 21

Which bands get smaller during muscle contraction?

Answer 21

I band
H band

Question 22

Which site is not supposed to move?

Answer 22

Origin - attached to bon

Question 23

Insertions

Answer 23

bone to bone

Question 24

What is the first step of muscle contraction? Explain it

Answer 24

Signalling or Activation
- The neuromuscular junction activates it using acetylcholine

Question 25

Neuromuscular junction

Answer 25

synapse gap where nerves talks to muscle (using neurotransmitters)

Question 26

Neurotransmitter for Muscle

Answer 26

Activated by acetylcholine

Question 27

Second Step of Muscle Contraction

Answer 27

- release calcium -Binds to troponin (prevents contraction) to move it so actin is exposed

Question 28

Where is calcium stored?

Answer 28

Sarcoplasmic reticulum

Question 29

Third Step in Muscle Contraction

Answer 29

Uses ATP to get shorter

Question 30

Rigor Mortis

Answer 30

Running completely out of ATP is only at death

Question 31

Endomysium

Answer 31

connective tissue inside muscles

Question 32

Perimysium

Answer 32

connective tissue surrounding muscle bundles

Question 33

Epimysium

Answer 33

envelops entire muscles

Question 34

What happens when the contraction cycle begins?

Answer 34

Arrival of calcium ions within the zone of overlap.

Question 35

What happens when the active site is exposed

Answer 35

Calcium ions bind to troponin, blocking the contraction. The troponin molecule then changes position, rolling the tropomyosin molecule away from the active sites on actin and allowing interaction with the energized myosin heads. - myosin head attaches to actin

Question 36

Cross Bridge Formation

Answer 36

Once the active sites are exposed, the energized myosin heads bind to them, pulling it towards the middle, forming cross-bridges.

Question 37

Myosin Head Pivoting

Answer 37

The energy that was stored in the resting state is released as the myosin head pivots toward the M line

Question 38

Power Stroke

Answer 38

- energy that was stored in the resting state is released as the myosin head pivots toward the M line - when it occurs, the bound ADP and phosphate group are released.

Question 39

What happens at cross bridge detachment

Answer 39

When another ATP binds to the myosin head, the link between the myosin head and the active site on the actin molecule is broken. - The active site is now exposed and able to form another cross-bridge. - Myosin head detaches from the actin

Question 41

Agonist

Answer 41

prime mover

Question 42

Antagonist

Answer 42

opposes movement of agonist

Question 43

Synergist

Answer 43

- smaller muscle that assists larger agonist

Question 44

Motor Units

Answer 44

- That contract at the same time - can be big and small

Question 45

Recruitment

Answer 45

multiple motor unit summation

Question 46

Tetanus

Answer 46

maximum contraction by all motor units

Question 47

Isotonic Contraction

Answer 47

occur when the muscle changes length, producing limb motion. - use same force

Question 48

Isometric Contraction

Answer 48

- contractions in which there is no change in the length of the muscle - holds at same place

Question 49

What are the three major types of skeletal muscle fibers?

Answer 49

Fast fibers Slow fibers Intermediate fibers

Question 50

Fast Fibers

Answer 50

- strong for short period of time

Question 51

Slow Fibers

Answer 51

- slow for long periods of time

Question 52

Intermediate Fibers

Answer 52

between slow and fast fibers