Florida Basic Recruit Training Program High Liability (First Aid) Practice Exam

Which type of muscle works continuously to expand and contract the heart?

1. Involuntary muscles

2. Skeletal muscles

3. Cardiac muscles

4. Smooth muscles

The correct answer is: Cardiac muscles

Cardiac muscles are specialized muscle tissues that are specifically designed for the continuous and rhythmic contraction necessary to pump blood throughout the heart and into the circulatory system. Unlike skeletal muscles, which are under voluntary control and are used for movement of bones, cardiac muscles are involuntary and function without conscious effort. They have unique properties such as the ability to contract in a coordinated manner, allowing the heart to function as a pump efficiently. Additionally, cardiac muscles have intercalated discs, which facilitate quick communication between cells, leading to synchronized contractions. This is essential for maintaining a consistent heartbeat. In contrast to smooth muscles, which are found in various internal organs and can contract slowly over longer periods, cardiac muscles must contract quickly and powerfully to meet the body's demands for blood. Thus, it is the specialized structure and inherent properties of cardiac muscles that enable them to continuously expand and contract the heart.