Muscle 1

Question 1

How are skeletal and cardiac muscle arranged?

Answer 1

Striated

Question 2

Arrangement of the nucleus in skeletal muscle

Answer 2

Multinucleated fibres, nucleus pushed up to the surface

Question 3

How is cardiac muscle arranged together?

Answer 3

Intercalated discs

Question 4

How do cardiac cells communicate?

Answer 4

Gap junctions

Question 5

What are muscle fibrils made of?

Answer 5

Thick (myosin) and thin (actin) protein

Question 6

How do muscle cells start in utero?

Answer 6

Myoblasts

Question 7

Can myoblasts replace muscle cells

Answer 7

No

Question 8

How can limited skeletal muscle be replaced

Answer 8

Some satellite cells exist

Question 9

How is smooth muscle replaced?

Answer 9

Can divide and replace very easily

Question 10

What encircles muscle fibres?

Answer 10

Connective tissue (areolar)

Question 11

How are muscles attached to bone?

Answer 11

Tendons

Question 12

How do surrounding muscle cells react to local muscle damage?

Answer 12

Hypertophy - they get bigger and stronger

Question 13

How does blood reach the muscle?

Answer 13

There is very deeply penetrating vessels

Question 14

What is the Z line?

Answer 14

Border between one repeating unit and another

Question 15

Whats the name given to a repeating muscle unit

Answer 15

Sarcomere

Question 16

What is the role of the titin filament?

Answer 16

Ensures myosin is always surrounded by actin

Question 17

How is the myosin energised to allow quick on demand contraction?

Answer 17

ATP is constantly hydrolysed to ADP and Pi on the myosin head.

Question 18

What proteins are attached to actin?

Answer 18

Troponin and tropomyosin

Question 19

What does tropomyosin do?

Answer 19

Blocks myosin binding sites

Question 20

What does troponin do?

Answer 20

Holds tropomyosin in place

Question 21

How does calcium reveal the binding sites?

Answer 21

Binds to troponin, causing it to twist and move the tropomyosin

Question 22

What is stored in the sarcoplasmic reticulum?

Answer 22

Calcium

Question 23

What is the role of transverse tubes in the muscle?

Answer 23

They propagate electrical signals into the core of muscle fibres to allow equal contraction

Question 24

What’s the combination of a muscle and a motor neurone called?

Answer 24

Motor unit

Question 25

If a motor unit is damaged, why don’t you lose the function of the muscle?

Answer 25

Multiple motor units innervate a muscle

Question 26

Whats tension?

Answer 26

Force exerted by a muscle

Question 27

What’s load?

Answer 27

Force exerted on the muscle

Question 28

What’s harder with heavier loads?

Answer 28

• Generation of required tension

- Fast contraction

Question 29

Isometric

Answer 29

Contraction without muscle shortening

Question 30

Isotonic

Answer 30

Contraction with shortening

Question 31

Lengthening

Answer 31

Contraction with muscle lengthening

Question 32

What is twitch?

Answer 32

A contraction produced by a single AP

Question 33

Since twitch is about 100 times longer than the AP, what does this allow?

Answer 33

The signal to be sustained in the muscle for longer

Question 34

If the period of time between AP’s is short what happens?

Answer 34

Contractions summate.

Question 35

What is tetanus with regard to muscle?

Answer 35

Sustained level of tension in any muscle fibre

Question 36

Unfused tetanus

Answer 36

Contraction fluctuating over a period of time

Question 37

Fused tetanus

Answer 37

sustained contraction over a long period of time

Question 38

Why do we fatigue?

Answer 38

Stops fused tetanus from constantly occurring, so calcium levels don’t stay high

Question 39

What is the length tension relationship?

Answer 39

Optimal length of a muscle fibre that will produce the strongest contraction

Question 40

How are skeletal muscles arranged with each other (hint: think of tricep and bicep)

Answer 40

• As 1 flexes the other extends

- Arranged as levers

Question 41

What does this arrangement allow?

Answer 41

Increased manoeuvrability