Lever system

Lever Systems

• Levers are simple machines that are present in the human body, assisting in the generation of force and movement.

• Each lever system in the body consists of a lever, a fulcrum (the point of pivot), an effort (the force that creates movement), and a resistance or load.

Types of Levers

• There are three types of levers in the body: First class, Second class, and Third class.

• First class lever: The fulcrum is located between the effort and the resistance. An example of this in the human body would be the triceps muscle extending the elbow.

• Second class lever: The resistance is located between the fulcrum and the effort. A real-life example is the action of the calves raising the body onto the toes.

• Third class lever: The effort is between the fulcrum and the resistance. An example is when the biceps curls the forearm.

Lever Advantages and Disadvantages

• Mechanical Advantage (MA): If the load arm is shorter than the effort arm, it is easier to move heavy loads. This is known as a Mechanical Advantage.

• Mechanical Disadvantage: If the load arm is longer than the effort arm, more force will need to be applied. This is called a Mechanical Disadvantage.

• First Class Lever advantage: Both a mechanical advantage and disadvantage can be achieved based on the placement of the fulcrum.

• Second Class Lever advantage: Always operates at a mechanical advantage, making it possible to move large loads with a relatively small amount of effort.

• Third Class Lever disadvantage: Operates at a mechanical disadvantage as the effort is applied between the load and the fulcrum. Despite this, they are the most common found in the body, due to their range and speed of movement.

Understanding Levers

• Knowledge of how levers work can aid an understanding of how body movements occur and the specific role that muscles play in these movements.

• Levers can also help explain why certain movements may require more effort than others, depending on their class.