Topic 11.2: Muscles and Movement

Question 1

What is the role of bones in human movement?

Answer 1

Provide a hard framework for stability and acts as levers (3rd class) to facilitate movement

Question 2

What is the role of ligaments in human movement?

Answer 2

Holds bones together

Question 3

What is the role of muscles in human movement?

Answer 3

Provide the force required for movement by moving one bone (point of insertion) in relation to another (point of origin)

Question 4

What is the role of tendons in human movement?

Answer 4

Connect muscles to bones

Question 5

What is the role of nerves in muscle movement?

Answer 5

Motor neurons provides the stimulus for muscle movement and co-ordinates sets of antagonistic muscles

Question 6

What is A?

Answer 6

Humerus

Question 7

What is Part B?

Answer 7

Triceps

Question 8

What is Part C?

Answer 8

Joint Capsule (with synovial fluid)

Question 9

What is Part D?

Answer 9

Cartilage

Question 10

What is Part E?

Answer 10

Ulna

Question 11

What is Part F?

Answer 11

Radius

Question 12

What is Part G?

Answer 12

Biceps

Question 13

What is the function of the biceps?

Answer 13

Bends the arm (flexor)

Question 14

What is the function of the triceps?

Answer 14

Straightens the arm (extensor)

Question 15

What is the function of the humerus?

Answer 15

Anchors muscle (muscle origin)

Question 16

What is the function of the radius/ulna?

Answer 16

Acts as forearm levers (muscle insertion) - radius acts as a lever for the biceps, ulna acts as a lever for the triceps

Question 17

What is the function of the cartilage?

Answer 17

Allows easy movement (smooth surface), absorbs shock and distributes load

Question 18

What is the function of synovial fluid?

Answer 18

Provides food, oxygen and lubrication to the cartilage

Question 19

What is the function of the joint capsule?

Answer 19

Seals the joint space and provides passive stability by limiting range of movement

Question 20

What are the similarities between the hip joint and knee joint?

Answer 20

Both are synovial joints

Both are involved in the movement of the leg

Question 21

What are the differences between the hip joint and knee joint? (4)

Answer 21

Question 22

Describe the structure of striated muscle fibres, including the myofibrils with light and dark bands, mitochondria, the sarcoplasmic reticulum, nuclei and the sarcolemma (6)

Answer 22

Each muscle fibre has the following specialised features designed to facilitate muscular contraction

Many nuclei (fibres are long and were formed from many muscle cells fusing together, hence the fibres are multinucleated)

Large number of mitochondria (muscle contraction requires a lot of ATP)

Tubular myofibrils, divided into sections called sarcomeres, and made of two different myofilaments (proteins responsible for contraction)

Where thin (actin) and thick (myosin) filaments overlap, a dark band occurs, and this is flanked by light regions containing thin filament only

The membrane surrounding a muscle fibre is called the sarcolemma

The internal membranous network is called the sacroplasmic reticulum, it is analogous to endoplasmic reticulum but is specialised for muscle contraction (it contains high levels of Ca2+ ions)

Question 23

What is Part A?

Answer 23

sarcoplasmic reticulum

Question 24

What is Part B?

Answer 24

nucleus

Question 25

What is Part C?

Answer 25

mitochondria

Question 26

What is Part D?

Answer 26

myofibril

Question 27

What is Part E?

Answer 27

thick (myosin) and thin (actin) filaments

Question 28

What is Part F?

Answer 28

sarcolemma

Question 29

What is Part A?

Answer 29

Z line

Question 30

What is Part B?

Answer 30

actin

Question 31

What is Part C?

Answer 31

myosin (with heads)

Question 32

Explain how skeletal muscles contract, including the release of calcium ions from the sarcoplasmic reticulum, the formation of cross-bridges, the sliding of actin and myosin filaments, and the use of ATP to break cross-bridges and reset myosin heads (7)

Answer 32

An action potential from a motor neuron triggers the release of Ca2+ ions from the sarcoplasmic reticulum Calcium ions expose the myosin heads by binding to a blocking molecule (troponin complexed with tropomyosin) and causing it to move The myosin heads form a cross-bridge with actin binding sites ATP binds to the myosin heads and breaks the cross-bridge The hydrolysis of ATP causes the myosin heads to change shape and swivel - this moves them towards the next actin binding site The movement of the myosin heads cause the actin filaments to slide over the myosin filaments, shortening the length of the sarcomere Via the repeated hydrolysis of ATP, the skeletal muscle will contract