Questions: Muscular System Overview

Question 1

Why do skeletal muscles need to work in pairs to move a joint?

• A. One muscle gets tired, so the other takes over
• B. Muscles can only pull (contract), not push, so two muscles pulling in opposite directions are needed to move a joint both ways
• C. Pairs of muscles are stronger than single muscles
• D. One muscle handles fast movements while the other handles slow movements

Answer: (B)

Muscles generate force in only one direction: they shorten (contract) and pull. A single muscle can bend your elbow by pulling your forearm up, but it cannot push your forearm back down. You need a second muscle on the opposite side to pull in the other direction. The biceps bends the elbow; the triceps straightens it. This opposing pair arrangement is the only way muscles can produce two-directional movement at a joint.

Question 2

The muscles in your stomach wall that churn food during digestion are skeletal muscles you control voluntarily.

• T. True
• F. False

Answer: False

The muscles in your stomach (and throughout your digestive tract) are smooth muscle, which operates involuntarily -- your nervous system controls them automatically without you having to think about it. You cannot consciously decide to churn your stomach faster. Skeletal muscles are the ones attached to bones that you control voluntarily, like the muscles in your arms and legs.

Question 3

Describe the three types of muscle tissue and where each is found in the body.

Model answer: Skeletal muscle is attached to bones and is under voluntary control -- it moves your arms, legs, and face. Smooth muscle is found in the walls of organs like the stomach, intestines, and blood vessels and works involuntarily. Cardiac muscle is found only in the heart and works involuntarily, beating continuously without tiring.

The three muscle types differ in structure, location, and control. Skeletal muscle is striated (striped) and voluntary. Smooth muscle is non-striated and involuntary. Cardiac muscle is striated but involuntary, with unique properties that allow it to beat rhythmically for a lifetime without fatigue -- a capability neither of the other two types has.