Topic 7

Question 1

skeletal muscle

Answer 1

• type of muscle you use to move e.g. the biceps and triceps move the lower arm

Question 2

tendons

Answer 2

• skeletal muscles are attached to bones by tendons

Question 3

ligaments

Answer 3

• attach bones to other boners, to hold them together

Question 4

Contraction of biceps

Answer 4

• when your biceps contracts your triceps relaxes

- this pulls the bone so your arm bends (flexes) at the elbow

Question 5

flexor

Answer 5

• a muscle that bends a joint when it contracts is called a flexor

Question 6

Contraction of triceps

Answer 6

• when your triceps contracts your biceps relaxes

- this pulls the bone so your arm straightens (extends) at the elbow

Question 7

extensor

Answer 7

• a muscle that straightens a joint when it contracts is called extensor

Question 8

muscle pairs

Answer 8

• muscles work in pairs because they can only pull (when they contract) - they can’t push
• so you need 2 muscles creating opposite forces to move a bone

Question 9

skeletal muscle structure

Answer 9

• made up of large bundles of long cells, called muscle fibres
• the cell membrane of muscle fibre cells is called sarcolemma
• parts of the sarcolemma fold inwards across the muscle fibre and stick into sarcoplasm
• these folds are called transverse (T) tubules and help to spread electrical impulses throughout the sarcoplasm to reach all the parts of the muscle fibre
• a network of internal membranes called the sarcoplasmic reticulum runs through the sarcoplasm
• these store and releases calcium ions that are needed for muscle contraction
• muscle fibres have lots of mitochondria to provide ATP that is needed for muscle contraction
• these are multinucleate (have multiple nuclei)
• muscle fibres have lots of long cylindrical organelles called myofibrils
• they’re made up of proteins and are highly specialised for contraction