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IB HL Biology > 11.2 Movement > Flashcards

11.2 Movement Flashcards

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1
Q

What do muscles need to be able to exert a force?

A
  • A muscle by itself may be able to contract, but it cannot exert force unless the muscle is attached to something.
  • In insects and crustaceans, the muscles are attached to the exoskeleton, which is an external structure usually made of chitin (a modified polysaccharide containing nitrogen) that protects the softer body parts of these animals.
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2
Q

Describe the hid legs of some insects insects

A
  • The hind legs in grasshoppers, fleas, cockroaches and other insects are perfectly adapted for jumping.
  • The muscles in these limbs work antagonistically , in other words, when one muscle contracts, the other relaxes.
  • For example, the hind limb of a cockroach has an extensor muscle and a flexor muscle.
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3
Q

Diagram of the hind limb of a cockroach

A
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4
Q

Describe a cockroach’s jumping sequence

A
  • When the flexor contracts and the extensor relaxes, the tibia flexes.
  • This is the first step in a jumping sequence.
  • The next step is the contraction of the extensor muscle and the relaxation of the flexor muscle.
  • The result is the extension of the tibia, and the cockroach jumps.
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5
Q

What do vertebrates have?

A

Bony endoskeletons

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6
Q

Movement of skeletal muscles in vertebrates

A
  • The skeletal muscles, which also occur in antagonistic pairs, are attached to bones.
  • For example, the muscles enabling you to lift your forearm are the triceps and biceps.
  • The biceps contract and the triceps relax when you bend your forearm towards your body
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7
Q

Diagram of the movement in a human forearm

A
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8
Q

Where are the bicep muscles located and what do they do?

A

They are located above the humerus and flex the forearm.

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9
Q

Where are the tricep muscles located and what do they do?

A

They are located underneath the humerus and extend the forearm.

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10
Q

What is the role of bones and the exoskeleton in organisms?

A

To provide anchorage for muscles and act as levers.

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11
Q

Movement of the body requires muscles to work in ___ pairs.

A

Antagonistic

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12
Q

Define an antagonistic muscle

A

In antagonistic muscles, one muscle always relaxes whilst the other contracts.

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13
Q

Which muscle must relax and which muscle must contract to extend the forearm?

A

The bicep relaxes and the tricep contracts

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14
Q

What is a joint?

A

A place where two bones come together.

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15
Q

Explain how a joint allows movement

A
  • A joint allows movement, but only in some directions.
  • Movement is made possible because the cartilage that covers the end of the bone prevents friction.
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16
Q

What is bone made up of?

A

Many materials, including calcium phosphate, collagen and an elastic protein.

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17
Q

What is cartilage made up of?

A
  • It is composed of specialized cells called chondrocytes.
  • These cells produce an extracellular matrix, composed of collagen fibers, proteoglycan, and elastin fibers.
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18
Q

What is the main function of cartilage?

A

To protect the ends of the bone.

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19
Q

What are synovial joints?

A
  • Joints that possess a synovial cavity between the two bones.
  • This cavity is filled with synovial fluid that reduces friction at the joint, allowing bones to move freely.
  • Synovial joints allow a high range of motion. However, synovial joints allow certain movements but not others.
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20
Q

How does a synovial joint prevent dislocation?

A
  • The synovial joint is enclosed in a joint capsule that helps prevent dislocation.
  • In the joint capsule, the synovial fluid reduces the friction between the bones by acting as a lubricant.
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21
Q

What is a dislocation?

A
  • An injury to a joint where the bone ends are forced from their normal positions.
  • This is very painful and stops you from moving your joint.
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22
Q

Diagram of the knee joint

A
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23
Q

Explain how the knee joint works

A
  • The knee joint allows your leg to extend and flex.
  • Your knee joint has more movement possibilities when it is flexed.
  • When your leg is fully extended, your knee is ‘locked’.
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24
Q

Does the hip joint have more or less flexibility than the knee?

A

More

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25
Q

Diagram of the hip joint and its possible range of motion

A
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26
Q

What does the hip joint allow you to do

A

Your hip joint allows your leg to flex, extend, rotate and swing from side to side.

27
Q

Diagram of the human elbow joint

A
28
Q

You should be able to annotate a diagram of the human elbow joint. Annotations should include ___

A

Cartilage, synovial fluid, joint capsule, named bones and named antagonistic muscles.

29
Q

What is the function of the synovial fluid in a joint?

A

It lubricates the joint and prevents friction.

30
Q

Which structure is the ulna in this diagram of the elbow joint?

A

Z

31
Q

What type of joint is a hip joint and what kind of movement does it allow?

A

It is a ball and socket joint that can flex and extend in many directions.

32
Q

What do skeletal and cardiac muscle cells look like when seen under a microscope?

A

Striated (striped)

33
Q

How are smooth muscles different from skeletal and cardiac muscles?

A
  • Smooth muscle does not have these striations.
  • Skeletal muscle cells are elongated, contain many nuclei and mitochondria (to supply the high ATP requirements), and are surrounded by a sarcolemma.
34
Q

Define the sarcolemma

A

The cell membrane of a striated muscle fibre cell.

35
Q

What are skeletal muscle cells?

A

Skeletal muscle cells (also called muscle fibres) can be more than 1 cm long and are the result of the fusion of many embryonic muscle cells.

36
Q

Diagram of a skeletal muscle fiber

A
37
Q

Describe the structure of a muscle fiber

A
  • They consist of many myofibrils and have a lot of endoplasmic reticula; however, in muscles, this is called the sarcoplasmic reticulum.
  • The sarcoplasmic reticulum stores calcium, which is needed for muscle contraction.
  • It surrounds each myofibril, allowing it to convey a signal to all parts of the muscle to contract or relax.
38
Q

Each myofibril of the muscle fibre consists of ___

A

Contractile sarcomeres

39
Q

What are contractile sarcomeres?

A

Subunits that can contract.

40
Q

Diagram showing an overview of the structure of striated muscle, with details of the myofibril and the sarcomere

A
41
Q

What is the sacromere?

A
  • The functional unit of the myofibrils, containing thick (myosin) and thin (actin) filaments.
  • Where the actin and myosin filaments overlap (a band in the diagram and corresponding dark area in the electron micrograph), the actin and myosin filaments form cross-bridges which bring about muscle contraction.
42
Q

You should be able to draw labeled diagrams of the structure of a sarcomere.

You are expected to include the following labels: ___

A

Z lines, actin filaments, myosin filaments with heads (see next section), and the resultant light and dark bands.

43
Q

The structure depicted in the figure shown above is found in:

A

Skeletal and cardiac muscles

44
Q

Which section of the figure represents the so-called “dark band”?

A

ii

ii represents the myosin portion of a sarcomere and that represents the “dark band” of the muscle fiber.

45
Q

What is the sliding filament theory?

A
  • Contraction of skeletal muscle can be explained by the sliding filament theory.
  • This theory was put forward following the discovery that the A band (myosin) is the same length in contracted and relaxed muscles.
  • According to this theory, the actin and myosin filaments slide over each other to make the muscle shorter: actin slides over myosin moving inwards towards the center of the sarcomere.
  • This makes the length of all the sarcomeres shorten, thus the entire muscle becomes shorter.
46
Q

What happens to sarcomeres when a muscle contracts?

A
  • When a muscle contracts, all the sarcomeres contract.
  • Each sarcomere exerts only a tiny amount of force, but altogether the result is substantial.
47
Q

Diagram showing the relaxed and contracted state of a sarcomere

A
48
Q

How does sliding of the filaments happen?

A

This is achieved by an interaction between the myosin heads, actin filaments, and ATP hydrolysis.

49
Q

Diagram showing the steps involved in sarcomere contraction

A
50
Q

What are the stages of the contraction of a sarcomere?

A

1) ATP attaches to the myosin head.
2) Myosin head detaches from its binding site on the actin filament.
3) ATP splits into ADP and P.
4) Myosin head cocks to an angle.
5) Myosin head attaches to the binding site on the actin filament.
6) As ADP and P detach, the myosin head changes position and pushes the actin filament along – this is known as the power stroke.
7) The myosin head detaches from the actin filament and reattaches to the next binding site, repeating the cycle. This achieves ‘movement’.

51
Q

What do actin filaments contain?

A
  • Actin as well as two proteins: tropomyosin and troponin.
  • Tropomyosin forms two strands that wind around the actin filament, covering the binding site for the myosin heads.
52
Q

What factors are necessary for the filaments to slide?

A

ATP hydrolysis and cross bridge formation

53
Q

What three factors (other than ATP hydrolysis and cross-bridge formation) is sarcomere contraction dependent on?

A

Calcium ions, and the proteins tropomyosin and troponin.

54
Q

What happens when a muscle receives a neuronal impulse to contract?

A

1) Calcium ions are released from the sarcoplasmic reticulum.
2) Calcium ions bind to troponin, which forces tropomyosin to move.
3) This move exposes the myosin-binding sites on the actin.
4) Myosin heads can now make a cross-bridge and pivot the actin filaments towards the center of the sarcomere.

55
Q

Diagram of the interaction of Ca 2 +, troponin, and tropomyosin during muscle contraction

A
56
Q

How can you analyze electron micrographs to find the state of contraction of muscle fibers?

A

A simple comparison of the distance between two Z lines and the width of the H zone should be enough to deduce which muscle is in a contracted or relaxed state.

57
Q

Electron micrographs of relaxed and contracted muscle fibers

A
58
Q

During the contraction of a skeletal muscle fiber, calcium ions ___

A

Bind with troponin, so that the myosin-binding sites on actin are exposed

59
Q

What is indicated by the letters X, Y, and Z?

A

X - dark band

Y - actin filament

Z - myosin filament

60
Q

During muscle contraction, what is caused by the binding of ATP to the myosin head?

A

Myosin heads detach from their binding sites

61
Q

Myofibrils have a lot of endoplasmic reticulum called sarcoplasmic reticulum.

The sarcoplasmic reticulum contains a large amount of which ion required in muscle contraction?

A

Calcium

62
Q

Bones are connected to other bones by ___, and bones are connected to muscles by ___

A

Ligaments

Tendons

63
Q

What structure within muscle tissue is surrounded by a membrane and is multinucleate?

A

Muscle fiber

The muscle fiber contains many myofibrils, which consist of sarcomeres. Muscle fibers are elongated cells, containing many nuclei and mitochondria (for ATP), and are surrounded by a sarcolemma (a membrane).

IB HL Biology (68 decks)

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