Skeleton

Question 1

An internal skeleton has many advantages over an external skeleton:

Answer 1

• It provides an internal framework for the body.
• It grows with the rest of the body.
• It is flexible, due to the many joints.
• It allows easy attatchment of muscles.

Question 2

What are bones and cartilage?

Answer 2

Both cartilage and bones are living tissues containing living cells. Because cartilage and bones are living tissues, they can be infected by bacteria and viruses. However, they are able to grow and repair themselves.

Question 3

Properties of a long bone.

Answer 3

• A long bone consists of a long shaft containing bone marrow with blood vessels. At each end there is a head covered with cartilage.
• Long bones are hollow, so they are able to grow and repair themselves.

Question 4

Fragility of bones.

Answer 4

• Even though bones are very strong they can easily be broken with a sharp knock.
• The bones of elderly people can lack calcium and phosphorus, which can result in osteoporosis, making them prone to fractures.
• In an accident it can be dangerous to move a person with a suspected bone fracture. Broken vertebrae in the backbone can damage the spinal cord resulting in paralysis or death.

Question 5

How does cartilage become bone?

Answer 5

In very early stages, the human skeleton is made of cartilage. By the process of ossification (the deposition of calcium and phosphorus), the cartilage is slowly replaced by bone. If some cartilage remains between the head and shaft, the bone and the person is still growing.

Question 6

What is in synovial joints?

Answer 6

Synovial joints, such as the ball and socket joints and hinge joints, contain synovial fluid, a synovial membrane, ligaments and cartilage.

Question 7

Which joint has the most movement?

Answer 7

• A ball and socket joint has a wider range of movement than a hinge joint,
• which is restricted to only an up-and-down movement.

Question 8

The forearm is raised and lowered by antagonistic muscles, the biceps and triceps:

Answer 8

• To raise the forearm, the biceps contracts and the triceps relaxes.
• To lower the forearm. the biceps relaxes and the triceps contracts.

Question 9

Bones in the arm.

Answer 9

• Humerus (upper arm).
• Radius (forearm on thumb side of the hand).
• Ulna (forearm on little finger side of the hand).

Question 10

Each part of a synovial joint has a special function:

Answer 10

• The synovial fluid acts as a cushion against shock and a lubricant for easy movement.
• A synovial membrane holds in the synovial fluid.
• Cartilage protects the bone.
• The ligaments hold the bones in place.

Question 11

What is an example of raising and lowering the forearm?

Answer 11

Raising and lowering the forearm is an example of a lever, with the elbow acting as a fulcrum (pivot). The effort is multipled resulting in a greater force.