Muscle System

Question 1

Name the two characteristics of skeletal muscles

Answer 1

• Cells are tubular, very long, striated, many nuclei per cell (too long to be controlled by one nuclei)
• Voluntary (consciously controlled)

Question 2

What are tendons

Answer 2

The fibers that attach skeletal muscles to bone

Question 3

what are the 4 characteristics of Cardiac muscles

Answer 3

• Only found in the heart
• Cells are tubular, arranged in a branched network giving them a netlike structure
• Cells are also striated with one nucleus per cell.
• Contraction is involuntary

Question 4

What are the 3 characteristics of smooth muscles

Answer 4

• Cells are long, tapered, arranged in sheets, non-striated, one nucleus per cell.
• Muscle contractions are involuntary (not consciously controlled)
• Forms many internal structures (but also the iris

Question 5

What does antagonistic mean and how does it relate to skeletal muscle movement?

Answer 5

Antagonistic means work opposite.

Skeletal muscles are doing work when they are contracting and they move our bones by working opposite to each other. For example, the bicep and triceps work to move the arm in opposite directions when each of them contracts.

Question 6

List the four main components of a muscle fiber (cell)

Answer 6

1. Myofibrils- cylindrical shape
   -hundreds of thousands found in a muscle fiber
   - made of myofilaments (contain actin and myosin)
2. Mitocondria- 300/ muscle fiber
3. Membrane- called the sarcolemma which means “flesh husk”. Controls what enters and exits the muscle cell
4. Cytoplasm- called the sarcoplasm

Question 7

What two types of filaments are myofibrils made of?

Answer 7

Actin and myosin

Question 8

Describe actin structure

Answer 8

• Actin is the thin filament
• It is two bead-like strands of protein wrapped around each other
• Attached to the Z-line

Question 9

Describe myosin structure.

Answer 9

• Myosin is the thick filament, 10x longer than actin
• It is also two strands of protein wrapped around each other
• Attached to the M-line

Question 10

What causes the striations in skeletal muscle fibers?

Answer 10

The arrangement of the myofilaments actin and myosin in a sequential order from one end of the muscle fiber to the other.

Question 11

What is a sarcomere?

Answer 11

• The functional unit of the muscle fiber
• Repeats over and over causing the striations
• Is composed of actin, myosin, troponin, tropomyosin
• Is bordered by Z-lines

Question 12

Do sarcomeres shorten during muscle contraction?

Answer 12

Yes! But the actin and myosin filaments that make them up do NOT change shape.

Question 13

What is myoglobin?

Answer 13

• Myoglobin- oxygen-binding pigment (similar to hemoglobin) in a skeletal muscle fiber
  * stores oxygen for use during muscle contractions

Question 14

List the 6 parts of the sarcomere involved in muscle contraction.

Answer 14

Actin, myosin, troponin, tropomyosin, calcium, ADP + Pi

Question 15

What part of the muscle is calcium released from?

Answer 15

Sarcoplasmic reticulum

Question 16

List the 11 steps involved in muscle contraction including calcium and ATP

Answer 16

1. Myosin wants to attach to actin to enable a muscle to contract
2. Troponin/tropomyosin is in the way
3. Calcium (released from the sarcoplasmic reticulum) attaches to
4. troponin and this moves tropomyosin out of the way
5. This allows the myosin head to attach to the actin
6. ATP is attached to myosin
7. It hydrolyzes and becomes ADP + Pi
8. This moves myosin to actin and allows it to attach
9. The myosin slides the actin past it moving the Z lines closer (ends of sarcomere). Sarcomere shortens and muscle is contracted.
10. For the myosin to detach, energy from ATP is needed
11. Myosin detaches and Z lines slide back to original place. Muscle is relaxed.

Question 17

What is creatine phosphate and when is it needed by a muscle?

Answer 17

• the main high-energy, phosphate-storage molecule of muscle
• stored in resting muscles.
• needed to produce ATP in muscle contractions

Question 18

If oxygen is NOT present in a contracting muscle, what process does a cell use to make ATP?

Answer 18

Aerobic cellular respiration.
* This creates ATP, water and carbon dioxide

Question 19

If oxygen is NOT present in a contracting muscle, what process does a cell use to make ATP?

Answer 19

Fermentation
* This creates ATP and lactate

Question 20

Label the sarcoplasmic reticulum and sarcomere

Answer 20

Did you do it

Question 21

Label the actin, myosin, troponin, tropomyosin

Answer 21

Did you do it?