Lecture 11

Question 1

What are the 4 functions of skeletal muscle?

Answer 1

Movement, heat production, posture, communication.

Question 2

Which tow Latin and Greek prefixes mean muscle?

Answer 2

“myo” and “sarco”

Question 3

What is a myofibre (myocyte)?

Answer 3

A single muscle cell/strand.

Question 4

What is a myofibril?

Answer 4

A group of contractile strands within a muscle cell (ie. myosin and actin arrangement)

Question 5

Muscle cells/fibres can be up to __cm, and are ________, cylindrical, _____ nuclear.

Answer 5

Muscle cells/fibres can be up to 40cm, and are parallel, cylindrical, multinuclear.

Question 6

What is striated muscle?

Answer 6

Striated muscle tissue is a muscle tissue that features repeating functional units called sarcomeres, in contrast with smooth muscle tissue which does not.

Question 7

Is skeletal muscle striated or smooth?

Answer 7

Striated.

Question 8

Myofilaments are arranged in a _________.

Answer 8

Myofilaments are arranged in a SARCOMERE.

Question 9

What is a sarcomere?

Answer 9

The repeating protein arrangement of myofilaments.

Question 10

What are myofilaments?

Answer 10

Thick or thin proteins in a sarcomere.

Question 11

What is the sarcolemma?

Answer 11

The cell membrane of a striated muscle fibre cell

Question 12

What is the function of the sarcoplasmic reticulum?

Answer 12

It is a type of ER which regulates Ca++ concentration in the cytoplasm of striated muscle cells.

Question 13

How long is a sarcomere before and during contraction?

Answer 13

2 µm, 1 µm

Question 14

What is the thick protein/filament in a sarcomere called?

Answer 14

Myosin

Question 15

What is the thin protein/filament in a sarcomere called?

Answer 15

Actin

Question 16

During muscle contraction, which sarcomere filament moves?

Answer 16

Actin, myosin does not move.

Question 17

Actin and myosin int_________.

Answer 17

Actin and myosin interdigitate

Question 18

Do both myosin and actin retain their length?

Answer 18

Yes!

Question 19

Which two things are essential for muscle contraction?

Answer 19

Ca++ ions and Energy (ATP)

Question 20

Muscle function depends on which 3 things?

Answer 20

1. length of muscle fibres
2. number of muscle fibres
3. arrangement of muscle fibres

Question 21

If a large ROM is required, muscle fibres are _______.

Answer 21

If a large ROM is required, muscle fibres are longer. Longer resting muscle = can shorten more, greater ROM.

Question 22

Muscle fibres usually run ________ to line of pull (sheet, bundle).

Answer 22

Parallel to line of pull (sheet, bundle)

Question 23

Tension (= force) is directly proportional to ________________.

Answer 23

Tension (= force) is directly proportional to cross-sectional area (CSA).

Question 24

With a greater number of muscle fibres, does CSA and tension increase or decrease?

Answer 24

Increase.

Question 25

What does it mean if muscle fibres are pennate?

Answer 25

Fibres run oblique to muscle tendon.

Question 26

What are the advantages/disadvantages of pennate muscle fibres?

Answer 26

Reduced shortening but increased CSA

Question 27

Even relaxed muscles are _______ ________.

Answer 27

Even relaxed muscles are SLIGHTLY ACTIVE. Nerve impulses activating muscle fibres.

Question 28

What is a motor unit?

Answer 28

A motor unit consists of one somatic neuron and the muscle fibres supplied by its branches (a dozen - 1000s).

Question 29

Does muscle tone produce movement?

Answer 29

No.

Question 30

What is the purpose of muscle tone?

Answer 30

To help stabilise joins, maintain posture, and keep muscles firm and healthy.