5.1 Skeletal muscle

Question 1

what is each muscle composed of?

Answer 1

muscle fibres

Question 2

what is the connective tissue called that bundles fibres together?

Answer 2

SARCOLEMMA

Question 3

what are the smaller fibres in muscles called?

Answer 3

myofibrils

Question 4

what do myofibrils contain?

Answer 4

2 types of protein

myosin and actin

Question 5

muscles are made of…

Answer 5

fasicles

Question 6

fascicles are made of…

Answer 6

muscle fibres

Question 7

muscle fibres are made of…

Answer 7

myofibrils

Question 8

myofibrils are broken down into…

Answer 8

sarcomeres

Question 9

sarcomeres are made of…

Answer 9

thin & thick filaments (actin and myosin)

Question 10

what are the I bands and why?

Answer 10

light - actin and myosin don’t overlap

only actin there

Question 11

what is the A band and why?

Answer 11

dark bands
appear darkest where actin and myosin overlap
darkness due to presence of thick myosin filaments

Question 12

where is the Z line found?

Answer 12

at the centre of each light band

Question 13

what is the distance between the two z lines?

Answer 13

the sarcomere

Question 14

what happens to the sarcomere when muscle contracts?

Answer 14

it shortens, z bands move closer and I bands nearly disappear

Question 15

what is the H zone?

Answer 15

a lighter coloured region in the centre of the dark band

Question 16

what is in the H zone?

Answer 16

only myosin filaments

Question 17

what are the two different types of muscle fibres in skeletal muscle?

Answer 17

slow twitch and fast twitch

Question 18

do slow twitch fibres contract slowly or quickly?

Answer 18

slowly

Question 19

are slow twitch fibres more or less powerful over time?

Answer 19

less powerful

Question 20

what are slow twitch fibres used for?

Answer 20

endurance activities

Question 21

do slow twitch fibres tire easily?

Answer 21

no

Question 22

where is slow twitch fibres energy gained from?

Answer 22

aerobic respiration

Question 23

what are slow twitch fibres rich in?

Answer 23

myoglobin, blood vessels and mitochondria

Question 24

Where are slow twitch fibres found in large proportion?

Answer 24

Muscles that maintain posture e.g. Back and calf muscles

Question 25

Do fast twitch fibres contract quick or slow?

Answer 25

Quickly

Question 26

Do fast twitch fibres give powerful contractions?

Answer 26

Yes for short periods

Question 27

What are fast twitch fibres used for?

Answer 27

Short birds of speed and power

Question 28

Do fast twitch fibres tire easily?

Answer 28

Yes

Question 29

Where do fast twitch fibres gain energy from?

Answer 29

Anaerobic respiration

Question 30

What colour are fast twitch fibres?

Answer 30

Pale

Question 31

What are fast twitch fibres low in?

Answer 31

Levels of myoglobin and blood vessels

Question 32

What do fast twitch fibres have more of?

Answer 32

More thick myosin filaments

Question 33

What do fast twitch fibres store?

Answer 33

Creatine phosphate

Question 34

What does creatine phosphate do?

Answer 34

Rapidly generates ATP from ADP in anaerobic conditions

Question 35

Where are fast twitch fibres found in high proportions?

Answer 35

In muscles that need short bursts of energy such as biceps and eyes

Question 36

What are myofibrils?

Answer 36

Long cylindrical organelles
Made of actin and myosin
Specialised for contraction
Lined up parallel to provide maximum force

Question 37

What is actin?

Answer 37

Filament consisting of two strands twisted around each other

Question 38

What is myosin?

Answer 38

The thick filament consisting of rod shaped fibres with bulbous heads that project to one side

Question 39

How many actin to one myosin?

Answer 39

Six