levers in the human body Flashcards
what are the parts of the lever?
the fulcrum, the effort, the load
what is the fulcrum?
the axis of rotation
what is the effort?
the point of application of the force
what is the load?
the mass of the object, body, or part being moved; also known as the resistance
what is the fulcrum in the human body?
where the bones come together
what is the effort in the human body?
the force applied through muscle contraction
what is the load in the human body?
the mass to be moved by the muscle
what is a first-class lever?
the fulcrum is located between the effort and the load
e.x a see-saw
what is an example of a first-class lever in the human body?
neck extention
the neck as it shifts from a position of flexion to extension
what is a speed advantage?
length of the load arm must be greater than the length of the effort arm (catapult)
what is a force advantage?
length of the effort arm must be greater than the length of the load arm (crowbar)
what is a second-class lever?
the load is positioned between the point of application of the effort and the fulcrum
e.x. a wheelbarrow
what is an example of a second-class lever in the human body?
calf raise
the ball of the foot/ankle area (the fulcrum) in combination with contraction of the gastrocnemius muscle (the effort)
what kind of advantage does a second-class lever have?
a force advantage
what is a third-class lever
the effort is located between the fulcrum and the load
e.x. a broom
