B5 - The Skeleton, Muscles and Joints Flashcards
What do skeletons provide?
• support
• protection
• a framework for muscle attachment to allow movement
Describe the skeleton of an invertebrate e.g. An earthworm
- Many invertebrate animals do not have a skeleton.
- Those that live in water can become quite large because the water buoys them up.
- Earthworms are supported by the pressure of the fluid inside their body.
- The fluid presses outwards against their muscular body wall.
Describe the skeleton of insects.
- Insects, along with spiders and crustaceans) have an external skeleton made of chitin. This gives them : a protective outer covering which supports the animal and a framework for muscle attachment.
- These animals all have jointed legs and their skeleton, muscles, and joints allow them to move. However, this hard covering can restrict growth. The animals have to shed their old skeleton at intervals and grow before the new skeleton hardens.
What parts of your skeleton are cartilage?
• the tip of your nose
• your ear lobes
• at the ends of your long bones, such as limb bones and ribs.
How is the skeleton designed to provide growth, framework, movement and flexibility?
Bone and cartilage are both living tissues. They have blood vessels and nerves and they can grow with the body. The internal skeleton forms a framework. Joints and muscles allow it to move. The many small bones of the spine give great flexibility.
What is ossification? What is the difference in cartilage in children and adults? How can forensic scientists tell the age of a person ?
- From about 6 weeks, minerals are deposited into the cartilage. These are mainly calcium phosphate. The cartilage becomes ossified – is turned into bone.
- Children have more cartilage at the ends of their bones than adults, because they are still growing. Forensic scientists can tell the age of a person from the skeleton, according to how much cartilage is still present.
Describe the structure of a long bone and how it results in its features .
Outer part of shaft = hardened bone = withstand compression. Shaft = fairly hollow = bone lighter than solid bones, but still strong.
Centre of the shaft = bone marrow and blood vessels. Some fat is stored here, and new blood cells are made.
What are the three different types of fracture ?
- Green stick – the bone is bent but not broken.
• Simple fracture – the bone is broken but the skin is intact. - Compound fracture – also called an open fracture; the
broken ends of the bone stick out through the skin.
What is osteoporosis and why is it dangerous?
Older people have osteoporosis (soft bones) and they are more susceptible to fractures, which may happen in a fall.
What happens when you bend you arm?
• Your biceps muscle contracts and your triceps muscle relaxes.
• As your biceps contracts, the tendon that joins it to the radius does not stretch.
• So it pulls the radius upwards and your arm bends.
What happens when you straighten your arm?
• Your triceps muscle contracts and your biceps relaxes.
• The tendon from the triceps pulls on the ulna.
• Your arm straightens.
What are antagonistic muscles?
When a pair of muscles acts together in this way, one contracting and the other relaxing.
How does the arm act like a lever?
When the arm bends and straightens it acts as a lever:
• The elbow is the pivot point (fulcrum).
• The hand moves through a larger distance than the muscles.
• The muscles exert a larger force than the load that the hand lifts.
What are joints? What are the different types?
Joints are where the end of one bone meets another bone. There are different types :
- fixed joint
- synovial joint
- hinge joint
- ball and socket joint
Define and give an example of a : fixed joint, hinge joint, ball and socket joint
Fixed joint - skull Hinge joint ( type of synovial joint ) - allows movement in one plane. This allows you to bend and straighten your arms and legs. Ball and socket joint ( type of synovial joint ) - Shoulder and hip joints. At these joints you can rotate the limb bones.
