Skeletal Muscle

Question 1

The muscular compromises how much of our total body weight?

Answer 1

40-60%

Question 2

What are the functions of the muscular system?

Answer 2

Movement
Posture
Storing/moving substances
Generating heat (shivering)

Question 3

What structure covers the entire muscle?

Answer 3

Epimysium

Question 4

What structure is made of connective tissue and encapsules fascicles?

Answer 4

Perimysium

Question 5

What are fascicles?

Answer 5

Bundles of muscle fibres

Question 6

Sarcoplasm is the site of what?

Answer 6

Anaerobic respiration (enzymes)

Question 7

What are satellite cells?

Answer 7

Stem cells that differentiate into myoblasts and then myofibrils

Question 8

Sarcomeres are the smallest unit of skeletal muscle and are compromised of what?

Answer 8

Myofilaments.

Question 9

Actin forms in a what type of strand?

Answer 9

Double helical strand

Question 10

What is the role of tropomyosin?

Answer 10

Interacts with actin, covers binding site, myosin heads cannot bind to actin.

Question 11

As well as tropomyosin, what other myofilament is associated with actin?

Answer 11

Troponin

Question 12

What three parts make up the thick myosin filament?

Answer 12

Globular head
Flexible region
Tail

Question 13

How many myosin molecules are there per thick filament?

Answer 13

300

Question 14

What are the three extra structural proteins in a sarcomere? Explain their role.

Answer 14

1. Titin - molecular spring, associates with myosin and actin.
2. Nebulin - attachment subunits of actin, gives helical structure, avoids separation.
3. Desmin - Z line, joins sarcomeres.

Question 15

What is the definition of a sarcomere?

Answer 15

Smallest unit of a muscle cell, contains myofilaments which contract to form tension within a muscle.

Question 16

Give a general outline of the sliding filament theory created by Huxley in 1954.

Answer 16

Filaments slide past each other, both filaments remain relatively unchanged in length, despite changes in gross muscle lengths.

Question 17

H zone consists of what?

Answer 17

Myosin only.

Question 18

During concentric contraction, actin is pulled along myosin, what happens to the sarcomere structure?

Answer 18

Z lines move closer.
H zone reduces.
I band reduces.
A band remains the same.

Question 19

What is the sarcolemma?

Answer 19

Excitable membrane that depolarises to pass on AP.

Question 20

What is the sarcoplasmic reticulum?

Answer 20

Interconnecting tubules which surround the myofibrils and regulate calcium levels within the muscle cell.

Question 21

What are T-Tubules?

Answer 21

Branch from sarcolemma and pass on AP to muscle fibre.

Question 22

Describe the cross-bridge cycle.

Answer 22

1. Tropomyosin covers binding site on actin.
2. AP arrives.
3. Calcium released from SR, binds to troponin = conformational change.
4. Tropomyosin uncovers binding site.
5. Hydrolysis of ATP on myosin head.
6. Cross-bridge formed.
7. Pi released from head, changes angle, facilitates power stroke.
8. Head picks up another ATP, binding breaks cross bridge.
9. Repeats until calcium levels drop.

Question 23

What is fat max?

Answer 23

The maximum amount of fat an athlete can burn per hours - endurance trained people utilise fat at a higher rate.

Question 24

If a fibre appears to have a deep red colour, what is there a high concentration of?

Answer 24

Myoglobin

Question 25

What creates the colour change in microscopic images?

Answer 25

Histochemical stain

Question 26

The periperal nervous system is composed of what two pathways?

Answer 26

Afferent and efferent.

Question 27

The afferent pathways originates from where to the CNS?

Answer 27

Sensory organs

Question 28

The efferent pathways originates the CNS and goes to where?

Answer 28

Muscle/limbs

Question 29

The golgi tendon organ has a ____ afferent neurone.

Answer 29

Inhibitive

Question 30

When excessively large forces are generated feedback from GTO causes what?

Answer 30

Activation of muscles to decrease.

Question 31

How do muscle spindles act in a protective manner?

Answer 31

If muscle stretches rapidly, contraction is caused to prevent overstretching.