Muscle I- Skeletal Muscle Structure and Function

Question 1

What are bundles of fascicles called?

Answer 1

Muscles

Question 2

What do skeletal muscle do?

Answer 2

Apply force to bones to control posture and body movements. Mostly under voluntary control

Question 3

What does “T” stand for in T-tubules

Answer 3

transverse

Question 4

How do muscles develop force?

Answer 4

Contracting/ shortening

Question 5

What 3 proteins are involved with excitation of the muscle cell?

Answer 5

• The voltage gated sensor (DHPR)
• The ryanodine receptor (RyR)
• The SR Calcium- ATPase (SERCA)

Question 6

What are the two types of myofilaments?

Answer 6

Actin (thin filament)

Myosin (thick filament)

Question 7

What are fibres, fascicles, and muscles sheathed in?

Answer 7

connective tissue

Question 8

What is. the cell membrane of the muscle fibre called?

Answer 8

sarcolemma

Question 9

What is the “thick” myofilament?

Answer 9

myosin

Question 10

What is the Sarcoplasmic reticulum?

Answer 10

extensive membrane network associated with T-tubules at regular intervals

Question 11

What is a muscle fibre composed of? What is the answer composed of?

Answer 11

myofibrils- repeating units called sarcomeres

Question 12

Where are cardiac muscles in the body?

Answer 12

Cardiac muscle is only the heart to generate force to pump blood around body. (not under conscious control)

Question 13

What is the shortened name for the Ryanodine receptor and what does it do?

Answer 13

• RyR

- acts as a passive calcium channel on the SR that can open to allow calcium ions out into the cell

Question 14

what is made of actin and myosin?

Answer 14

sarcomeres

Question 15

Explain the processes that allow relaxation of the muscle to occur

Answer 15

• SERCA senses the rise in intracellular calcium
• It then burns some ATP to produce energy which is then used to pump calcium back into the SR, against concentration gradient
• the removal of calcium ions from the call stops the signalling event and allows the muscles to relax

Question 16

Explain the processes involved with the “excitement” section of EC coupling

Answer 16

• Signal coming from nerves is transmitted down T tubules
• This signal activates the DHPR which interacts with the RyR, causing them to open
• calcium ions pour out into the cell from SR
• This calcium diffuses through the cell, activating myofilaments and causing contraction

Question 17

What is the shortened name for the voltage gated sensor and what does it do?

Answer 17

• DHPR

- receives signals from the T tubules and interacts with the ryanodine receptor

Question 18

What are the tube-like extensions of the sarcolemma called?

Answer 18

T- tubules

Question 19

What are sarcomeres made of?

Answer 19

contractile proteins called myofilaments

Question 20

What is EC-coupling?

Answer 20

The pairing of a signalling event ( excitation of muscle cell) with a mechanical event (contraction of the muscle cell)

Question 21

What are T-tubules?

Answer 21

tube-like extensions of the sarcolemma

Question 22

What are fascicles?

Answer 22

Bundles of muscle fibres

Question 23

Is actin the “thick” or “thin” myofilament?

Answer 23

thin

Question 24

Where are smooth muscles in the body?

Answer 24

Mainly line hollow organs ( not under conscious control)

Question 25

What are the 3 main “types” of muscles in the human body?

Answer 25

Smooth, Cardiac, Skeletal

Question 26

What is the shortened name for SR calcium- ATPase and what. does it do?

Answer 26

• SERCA

an active calcium pump that uses ATP to move calcium ions back into the SR against its concentration gradient

Question 27

What is the full name of EC-coupling

Answer 27

Excitation contraction coupling

Question 28

What does the SR do and what is the full name

Answer 28

The sarcoplasmic reticulum intakes and stores calcium ions while the muscle is relaxed, and releases it into the cytoplasm when the muscle contracts

Question 29

What are bundles of muscle fibres called?

Answer 29

Fascicles

Question 30

What is the role of the T-tubules?

Answer 30

conduct electrical signals deep into the core of the fibre