Muscles 1

Question 1

What do muscles do?

Answer 1

Generate force, movement and allow us to express and regulate ourselves

Question 2

What are the two types of muscles we have in our body?

Answer 2

Smooth and striated

Question 3

What two types of striated muscles are there?

Answer 3

Skeletal and cardiac

Question 4

Skeletal muscles forms what structures and describe their nucleus/nuclei

Answer 4

Fibres which a multinucleate

Question 5

What are the typical dimensions of a skeletal muscle fibre?

Answer 5

10-100 micrometers in diameter and up to 20cm long

Question 6

Fibres form where and from what?

Answer 6

in utero from mononucleate myoblasts

Question 7

Do myoblasts replace cells if damaged?

Answer 7

No

Question 8

What happens to muscle fibres during growth?

Answer 8

They increase in size, not quantity

Question 9

What encases muscle fibres?

Answer 9

Connective tissue

Question 10

What cells replace damaged muscle cells after injury?

Answer 10

Satellite cells

Question 11

How do satellite cells form new muscle cells?

Answer 11

They differentiate (specialisation)

Question 12

How can other fibres compensate for adjacent fibres being damaged?

Answer 12

Hypertrophy (getting bigger)

Question 13

Describe the action cycle of a sarcomere

Answer 13

1. Muscle action potential propagated
2. Calcium ions released from lateral sac
3. Calcium binds to troponin - removing the blocking action of tropomyosin
4. The myosin head binds to the actin filament and moves to contract the muscle
5. ATP binds to the cross bridge to detach the filament linkage
6. Calcium ions are pumped into the lateral sac
7. Calcium removal from troponin restore blocking action of tropomyosin

Question 14

What two receptors mediate the movement of calcium ions in the action cycle?

Answer 14

DHP (voltage sensitive calcium channel) and Ryanodine receptor

Question 15

What is a motor unit?

Answer 15

Motor neurons and muscle fibres as a unit

Question 16

A force exerted by a muscles is a _____

Answer 16

Tension

Question 17

A force exerted on a muscle is the _____

Answer 17

Load

Question 18

Short latent period and longer contraction time is indicative of what kind of contraction

Answer 18

Isometric

Question 19

Longer latent period and shorter contraction time is indicative of what kind of contraction?

Answer 19

Isotonic

Question 20

What is the latent period?

Answer 20

The time before excitation contraction begins

Question 21

Contraction time is what?

Answer 21

The time taken between the start of a contraction and its peak tension

Question 22

What is the typical range of contraction time?

Answer 22

10-100 microseconds

Question 23

What is contraction time mediated by?

Answer 23

Calcium ion concentration

Question 24

As load increases, what happens to contraction velocity and distance?

Answer 24

They’re shortened

Question 25

What is the typical duration of action potentials in muscles?

Answer 25

1-2 microseconds

Question 26

Summation occurs when?

Answer 26

When action potentials immediately or just after a previous action potential

Question 27

Tetanic tension is greater than twitch tension because?

Answer 27

[Calcium ion] never gets low enough to allow troponin/tropomyosin to block myosin binding sites

Question 28

What does movement at a limb require?

Answer 28

Two antagonistic groups of muscles

Question 29

What do level systems of muscles accomplish?

Answer 29

Allows muscles to exert an amplified force - shortening velocity producing increases manoeuvrability