Lever Systems The human body is a system

Lever Systems The human body is a system of levers and pulleys which enables us to move. Levers are important in movement because they allow efficiency and force to be applied to the body’s movements. Levers are used to make a small amount of force into a much bigger force. This is known as gaining mechanical advantage. There are four parts to a lever: 1. Lever Arms – these are the structures that are moved in the body (the bones 2. Fulcrum – this is the pivot point where the lever arm moves around (joints) 3. Effort – this is the force used to move loads (muscles) 4. Loads – these are the forces resisting against movement (weight of body parts being moved or weights/equipment) There are three different types of lever in the human body: 1. First Class Lever 2. Second Class Lever 3. Third Class Lever https: //www. youtube. com/watch? v=d 1 w. S_Ol. Jzm. I

First Class Levers Effort Definition: This is a lever where the fulcrum (pivot) occurs in-between the effort and load. Load Lever Arm Fulcrum Muscles in the neck contracting Weight of the head Example: The neck joint is a good example of the action of a first class lever in the body. Vertebrae Neck Joint When heading a ball in football the neck muscles contract moving the weight of the head around the joint.

Second Class Levers Load Definition: This is a lever where the load occurs in-between the effort and fulcrum (pivot). Lever Arm Effort Weight of body & gravity Gastrocnemius contracting Ankle Joint Fulcrum Example: The ankle joint is a good example of the action of a second class lever in the body. When going on tip-toes (plantar flexion) the weight gets pushed upwards.

Third Class Levers Load Definition: This is a lever where the effort occurs in-between the fulcrum (pivot) and the load. Lever Arm Fulcrum Dumbbell weight Arm Bones Elbow Joint Effort Example: This is the most common form of lever in the human body. The best examples re the knee and elbow. The biceps contract during a bicep curl and force the weight upwards. Bicep muscle

Mechanical Advantage Levers are used because they allow us to use take a small amount of force and turn it into a bigger force. This is known as gaining mechanical advantage – a higher mechanical advantage means that lever is more efficient. Load and effort are forces and are measured in Newtons (N). Mechanical advantage (MA) is calculated as follows: MA = Load ÷ Effort eg: the load = 1000 N and the effort = 100 N then MA = 1000 ÷ 100 = 10