6.3 Skeletal muscle

Question 1

Describe the structure of Skeletal muscles

Answer 1

1. muscle tissue made up of muscle fibres
2. muscle fibres made up of myofibrils - long thin cells that contain many nuclei
3. sarcolemma, sarcoplasm and sarcoplasmic reticulum

Question 2

What is the sarcolemma?

Answer 2

cell membrane of the muscle fibre

Question 3

What is the role of a tendon?

Answer 3

connects muscle to bone

Question 4

What are striations?

Answer 4

patterns formed by myofibrils inside each muscle fibre seen under a light microscope

Question 5

where is the myofibrils located?

Answer 5

in the sarcoplasm of the muscle fibre

Question 6

What are the 4 myofilaments?

Answer 6

actin
Tropsin
Tropomyosin
myosin

Question 7

Why does muscle sarcoplasm have lots of mitochondria?

Answer 7

to produce ATP for contraction and resp

Question 8

What is a sarcomere?

Answer 8

repeat unit of myofibril proteins that have arranged themselves this way

Question 9

Which myofilament protein is lighter in colour?

Answer 9

actin

Question 10

Which myofilament protein is the thick filament?

Answer 10

myosin

Question 11

Which myofilament protein is darker in colour?

Answer 11

myosin

Question 12

Which myofilament protein is the thinner filament?

Answer 12

actin

Question 13

what are all the sections to a sarcomere structure?

Answer 13

Z lines
I bands
A band
M line
H zone

Question 14

What are the Z lines?

Answer 14

mark the boundary of the sarcomere

Question 15

What is the M line?

Answer 15

marks the middle of the myosin

Question 16

What is the I band?

Answer 16

where only actin is present

Question 17

What is the H zone?

Answer 17

where there is only myosin

Question 18

What is the A band?

Answer 18

where there is both actin and myosin

Question 19

What are the 2 types of muscle?

Answer 19

slow twitch and fast twitch

Question 20

What is the use of slow twitch muscle?

Answer 20

endurance

Question 21

What is the use of fast twitch muscles?

Answer 21

bursts of activity

Question 22

What are 2 examples of slow twitch muscles?

Answer 22

back muscles and calf muscles

Question 23

What are 2 examples of fast twitch muscles?

Answer 23

biceps and eye muscles

Question 24

Describe slow twitch muscle contraction

Answer 24

contract slowly and for longer time
they fatigue slowly

Question 25

Describe fast twitch muscle contraction

Answer 25

contract and relax rapidly
they contract quickly
fatigued rapidly

Question 26

Describe slow twitch muscle myofibrils

Answer 26

they low density of myofibrils with many mitochondria

Question 27

Describe fast twitch muscle myofibrils

Answer 27

high density of myofibrils with fewer mitochondria

Question 28

What type of respiration occurs in slow twitch muscles?

Answer 28

aerobic

Question 29

What type of respiration occurs in fast twitch muscles?

Answer 29

anaerobic

Question 30

Which type of muscle has a higher conc of myoglobin?

Answer 30

slow twitch

Question 31

Which type of muscle removes lactate quickly?

Answer 31

slow twitch

Question 32

Which type of muscle has a higher glycogen storage?

Answer 32

fast twitch

Question 33

What colour is slow twitch muscle?

Answer 33

dark

Question 34

What colour is fast twitch muscle?

Answer 34

light

Question 35

What is a neuromuscular junction?

Answer 35

where a motor neurone meets a muscle

Question 36

Describe how a nervous impulse is transmitted across a neuromuscular junction

Answer 36

1. AP arrives at motor neurone axon terminal
2. Ca channels open and Ca flood into the presynap neurone
3. synaptic vesicles fuse with presynap membrane to release Ach
4. Ach diffuses across synaptic cleft to postsynap membrane
5. Na gated channels in sarcolemma open and NA diffuse in rapidly
6. sarcolemma becomes depolarised - depolarisation passes down the t-tubules that branch through the sarcoplasm