11.2 Movement Flashcards
What are exoskeletons?
Exoskeletons are external skeletons that surround and protect most of the body surface of animals such as crustaceans and insects.
What is a bone’s role in movement?
Bones and exoskeletons facilitate movement by providing an anchorage for muscles and by acting as levers. Levers change the size and direction of forces. In a lever there is an effort force, a pivot point called the fulcrum and a resultant force. The relative positions of these determine the class of lever.
What is the fulcrum?
Pivot point of a lever.
What are the classes of lever?
First class - EFFORT FULCRUM RESULTANT
Second class - FULCRUM RESULTANT EFFORT
Third class - FULCRUM EFFORT RESULTANT
Which is the bicep?
The front muscle of the arm, the one on top that shows muscle
What is the tricep?
The back muscle of the arm
What is the humerus?
The bone in the arm between the biceps and triceps.
What is the radius?
The smaller bone on top in the lower half of the arm
What is the ulna?
The larger bone below in the lower half of the arm
What is a first class lever?
Effort fulcrum resultant
For example nodding your head backwards
What is a second class lever?
Fulcrum resultant effort
For example lifting up on to your tip toes
What is a third class lever?
Fulcrum effort resultant
For example moving your arm down.
What are antagonistic muscles?
Skeletal muscles occur is pairs that are antagonistic. This means that when one muscle contracts, the other relaxes. Antagonistic muscles produce opposite movements at a joint. For example, in the elbow, the triceps extends the forearm while the biceps flex the forearm.
How does the hind-leg of a grasshopper work?
The grasshopper has a jointed back leg. The flexor muscles are on the inside of the upper back leg, the extensor muscles are on the outside. When the grasshopper is preparing to jump the flexor (inside) muscle contracts and the extensor relaxes bringing the leg in. When he jumps the flexor muscles relax and the extensor muscles contract bringing the leg out.
The fulcrum is called the tibia.
LOOK AT DIAGRAM 478
What is a joint?
A point where bones meet.