H05&06: Muscle & Tendon

Question 1

What are the 3 types of muscle?

Answer 1

Skeletal/striated muscle
Smooth muscle
Cardiac muscle

Question 2

Which muscle type is under voluntary control?

Answer 2

Skeletal muscle

Question 3

Where is cardiac muscle found?

Answer 3

Around the heart

Question 4

Where is smooth muscle found?

Answer 4

Around organs

Question 5

What is the role of satellite cells in muscle?

Answer 5

They help with muscle cell repair

Question 6

How is skeletal muscle formed?

Answer 6

1) Myoblasts fuse end to end to form myotubes.
2) Myotubes synthesise contractile proteins (myofibrils).
3) Myofibrils mature into muscle cells.
4) Nuclei of muscle cells is pushed into the periphery and the muscle cells become packed with contractile proteins.

Question 7

What are particularities of skeletal muscle cells?

Answer 7

They are extremely long (can be up to cms long) & they are multinucleated.

Question 8

What are the 4 layers of CT associated with skeletal muscle?

Answer 8

Tendons are rope-like CT that attaches muscle to bone.
Epimysium is the outermost layer of CT that surrounds many muscle fascicles.
Perimysium surrounds many myofibrils to form muscle fascicles.
Endomysium surrounds individual myofibrils, it is the innermost layer of CT.

Question 9

Which band is the dark band and what is it made of?

Answer 9

The A band contains myosin filaments

Question 10

Which band is the light band and what is it made of?

Answer 10

The I band contains actin filaments.

Question 11

What is the sarcolemma?

Answer 11

The membrane of the myofibre

Question 12

What is special about the sarcolemma?

Answer 12

It is highly invaginated to wrap around each myofibre and allow contact between T-tubules and sarcoplasmic reticulum.

Question 13

What is the sarcoplasmic reticulum?

Answer 13

It is a specialised smooth ER that stores calcium.

Question 14

State the 3 types of metabolism & explain how each works.

Answer 14

Creatinine phosphate involves using creatinine phosphate to phosphorylate ADP to produce ATP & creatinine
Aerobic metabolism involves hydrolysing ATP to provide energy.
Anaerobic metabolism is the breakdown of glycogen.

Question 15

How does the life span of the 3 types of metabolism compare?

Answer 15

Creatinine phosphate and anaerobic metabolisms are short-lived while aerobic metabolism is long-lived.

Question 16

Which metabolism is used by all types of muscle fibre?

Answer 16

Creatinine phosphate

Question 17

State the 3 types of muscle fibres and the metabolism used by each.

Answer 17

Type I: uses aerobic metabolism
Type IIA: uses aerobic and anaerobic metabolism
Type IIB: uses anaerobic metabolism

Question 18

What colour are each of the muscle fibres?

Answer 18

Type I is red
Type IIA is pink
Type IIB is white

Question 19

What is the role of myoglobin?

Answer 19

It stores oxygen

Question 20

What are type I muscle fibres used in?

Answer 20

Posture

Question 21

What are type IIA muscle fibres used in?

Answer 21

Locomotion

Question 22

Compare the twitch velocity, resistance to fatigue, rate of ATP hydrolysis and ATP generation capacity of the 3 types of muscle fibres.

Answer 22

Type I is slow twitching whilst type IIA & IIB are fast twitching.
Type I has a low rate of ATP hydrolysis while type IIA & IIB have high rates of ATP hydrolysis.
Type I has a high resistance to fatigue, type IIA has moderate resistance to fatigue and type IIB has low resistance to fatigue.
Type I has high ATP generation capacity while types IIA & IIB have low ATP generation capacity.

Question 23

What are type IIB muscle fibres used in?

Answer 23

Rapid force

Question 24

What are synergistic actions?

Answer 24

When muscles work together.

Question 25

What are antagonistic actions?

Answer 25

When muscles oppose each other.

Question 26

Which muscle primarily moves a limb?

Answer 26

The antagonist muscle

Question 27

What are tendons made of?

Answer 27

Dense regular CT

Question 28

What are aponeuroses made of?

Answer 28

Dense regular CT

Question 29

How can muscles be attached directly to bone?

Answer 29

Using Sharpey's fibres. They are dense tufts of collagen that directly extend from the periosteum into the endomysium of attaching muscles.

Question 30

How is the musculotendinous junction adapted to withstand high impact?

Answer 30

It is not clear-cut and has finger-like projections to decrease the load on the membrane.

Question 31

How does the last sarcomere of a muscle attach to the tendon?

Answer 31

It has long, projecting actin filaments so it is much larger than the usual sarcomere.

Question 32

How are actin filaments attached to the tendon?

Answer 32

Integrins link the actin filament to the collagen-rich matrix. One set of integrins link the sarcolemma to the basement membrane and a second set of integrin proteins attach the basement membrane to collagen fibres.

Question 33

How are tendons protected?

Answer 33

By sesamoid bones, synovial bursae, synovial tendon sheath, synovial membrane.

Question 34

How do sesamoid bones protect tendons?

Answer 34

They prevent wear and tear as the tendon runs over the joint.

Question 35

How do synovial bursae protect tendons?

Answer 35

They are fluid-filled sacs between bones, muscles & tendons that provide cushioning & reduce friction.

Question 36

How do synovial tendon sheath protect tendons?

Answer 36

They protect tendons from abrasion as they move.

Question 37

How does the synovial membrane protect tendons?

Answer 37

Some cells in the synovum secrete glycosaminoglycans (hyaluronic acid) and glycoproteins (lubricin) that lubricate tendons. There are also phagocytic cells that recycle & remove damaged parts of the synovial membrane.

Question 38

How do tendons get their blood and nerve supply?

Answer 38

Through the mesotendon, a small gap that allows small blood vessels and single nerve fibres through.