Skeletal Muscles

Question 1

What are skeletal muscles?

Answer 1

Muscles that are attached to the skeleton

Question 2

What do skeletal muscles do?

Answer 2

Bring about movement of parts of the body

Question 3

How do skeletal muscles perform their function?

Answer 3

Through contraction and relaxation

Question 4

What are the characteristics of skeletal muscles?

Answer 4

Attached to the skeleton by inelastic tendons
They are striated
They are under voluntary control

Question 5

What is the structure of a skeletal muscle?

Answer 5

Made up of bundles of muscle fibres
They are bound together by connective tissue known as the perimysium
These bundles are enclosed by the epimysium

Question 6

What is a muscle fibre like?

Answer 6

A single elongated, cylindrical cell

Consists of thousands of myofibrils

Question 7

What are myofibrils like?

Answer 7

They contain two types of protein filaments

Question 8

What protein filaments do myofibrils contain?

Answer 8

Myosin

Actin

Question 9

What are myosin filaments like?

Answer 9

Thicker and darker

Question 10

What are actin filaments like?

Answer 10

They are thinner and lighter

Question 11

How are actin and myosin positioned in a myofibril?

Answer 11

They overlap in certain areas

Question 12

Which filaments form the dark bands in myofibrils?

Answer 12

They regions where active and myosin overlap

Question 13

Which filaments form light bands in myofibrils?

Answer 13

The sections with only actin

Question 14

What is the Z-line?

Answer 14

A line which bisects the dark bands on a myofibril

Question 15

What is a sarcomere?

Answer 15

The region between two Z-lines

It is the functional unit of a muscle

Question 16

What causes the contraction and relaxation of muscles?

Answer 16

Nerve impulses

Question 17

What happens during contraction of muscles?

Answer 17

The thin actin filaments slide past the thicker myosin filaments
The Z-lines then move closer together
The sacromere is shortened, which shortens the myofibrils, which shortens the muscle fibre, which shortens the whole muscle

Question 18

How are skeletal muscles often arranged?

Answer 18

In pairs

Question 19

Why are skeletal muscles arranged in pairs?

Answer 19

So that the one contracts as the other relaxes

Question 20

What are antagonistic muscles?

Answer 20

Muscles which work in opposite directions, pulling on the same bone

Question 21

Why are antagonistic muscles important?

Answer 21

They make coordinated movements possible

Question 22

Give an example of antagonistic muscles

Answer 22

Biceps and triceps

Question 23

Where are the biceps situated?

Answer 23

To the front of the upper arm

Question 24

Why are the biceps called biceps?

Answer 24

The muscle is attached to the pectoral girdle with two tendons

Question 25

What other bone is the bicep attached to?

Answer 25

Radius

Question 26

Where do the triceps occur?

Answer 26

At the back of the upper arm

Question 27

Why are the triceps called the triceps?

Answer 27

They are attached to the pectoral girdle with three tendons

Question 28

What other bone is the tricep attached to?

Answer 28

The ulna

Question 29

What happens when the biceps contract and the triceps relax?

Answer 29

The elbow joint bends and the forearm is raised

Question 30

What happens when the triceps contract and the biceps relax?

Answer 30

The elbow joint extends and the forearm is lowered

Question 31

What is an agonist?

Answer 31

The muscle which contracts

Question 32

What is an antagonist?

Answer 32

The muscle which relaxes

Question 33

What is a flexor?

Answer 33

A muscle which serves to bend a part of the body

Question 34

What is an extensor?

Answer 34

A muscle which serves to extend or straighten a part of the body