Question

1. Differentiate among the three classes of levers in terms of the relative position of fulcrum, effort, and load, as well as in terms of the relative power and range of motion.

2. Give examples in the human body of muscles and their associated joints to illustrate each type of lever system.

3. Define the terms prime mover (or agonist), antagonist, synergist, and fixator.

4. For a given movement, differentiate specific muscles that function as the prime mover, antagonist, synergist or fixator.

5. Explain how the name of a muscle can help identify its action, appearance, or location.

6. Define the terms tension and contraction, with respect to muscles.

7. Define the term motor unit.

8. Demonstrate isotonic and isometric contraction and interpret graphs of tension vs. time and muscle length vs. time for each type of contraction.

9. Describe, in order, the events that occur at the neuromuscular junction that elicit an action potential in the muscle fiber.

10. Provide specific examples to demonstrate how the muscular system responds to maintain homeostasis in the body

11. Explain how the muscular system relates to other body systems to maintain homeostasis

Answer 1

In first class lever, fulcrum is located between load and effort.

In second class lever, load is located between fulcrum and effort.

In third class lever, effort is applied between load and fulcrum.

In first class lever system, if effort is closer to fulcrum then range of motion and effort required is high and vice versa if load is closer to fulcrum.

In second class lever, range of motion and effort required is both less.

In third class lever, range of motion and effort required is both high.

An example of first class lever is joint between head and first vertebra wherein the head is the load, the fulcrum is the atlanto-occipital joint and the effort is provided by the posterior muscles.

An example of second class lever is the tip of toe or metatarsophalangeal joint. The body is the load, the achilles tendon provides the effort and the metatarsophalangeal joint is the fulcrum.

Example of third class joint is elbow joint. The elbow joint is the fulcrum, the effort is the flexed biceps, and the load is the forearm,hand and wrist.

The agonist muscle in a pair contracts while the antagonist muscle relaxes to produce a flexion and during extension the roles of the muscle pair interchanges.

The fixator muscle, also known as synergist muscle helps the agonist muscle to contract by stabilising the joint.

In elbow bending action, a flexion is taking place where biceps act as agonist and triceps act as antagonist. The brachialis is the synergist muscle which aids biceps in flexion.

When elbow returns to original position, the triceps are contracting hence they act as agonist and the biceps relax to act as antagonist and the synergist muscles are anconeus muscle which helps the triceps contract.