Muscular System Practice Test

The muscular system is responsible for movement in the body. Muscles are attached to bones and when they contract, they cause movement of the bones, allowing us to move our limbs, walk, run, and perform various activities. This function of the muscular system is essential for our mobility and ability to interact with the environment.

Cardiac muscle is found exclusively in the heart. It is a specialized type of muscle that contracts rhythmically and continuously to pump blood throughout the body. The unique structure of cardiac muscle allows it to withstand constant contraction and relaxation without fatigue. This muscle type contains intercalated discs, which facilitate synchronized contractions and ensure efficient pumping action. Due to its vital role in maintaining circulation, cardiac muscle is only present in the heart and not found in any other part of the body.

Cardiac muscle is a type of muscle that is found only in the heart. It is responsible for the continuous pumping of blood throughout the body. Unlike skeletal muscle, which is under voluntary control, cardiac muscle is involuntary and contracts rhythmically to maintain the heart's pumping action. Cardiac muscle cells are striated and interconnected, allowing them to work together as a coordinated unit. This type of muscle is highly specialized and adapted to meet the demands of the cardiovascular system.

The correct structure of muscle fiber is muscle-muscle fiber-myofibrils. This is because muscle fibers are the basic units of muscle tissue, and they are composed of smaller structures called myofibrils. Myofibrils are made up of contractile proteins called actin and myosin, which are responsible for muscle contraction. Therefore, the correct order is muscle-muscle fiber-myofibrils.

The sliding filament theory explains how muscles contract. According to this theory, myosin, a protein in muscle cells, pulls on actin, another protein, causing the muscle to shorten and contract. This is the correct answer because it accurately describes the process of muscle contraction in the sliding filament theory.

Smooth muscle is found in internal organs. This type of muscle is involuntary and non-striated, meaning it lacks the striped appearance seen in skeletal muscle. Smooth muscle is responsible for the contraction and relaxation of various organs in the body, such as the stomach, intestines, blood vessels, and bladder. It helps in the movement of substances through these organs and plays a crucial role in bodily functions like digestion, circulation, and urination.

Skeletal muscles are attached to bones by tendons. Tendons are tough, fibrous connective tissues that connect muscles to bones, allowing for movement and providing stability to the skeletal system. This attachment allows skeletal muscles to exert force on the bones, enabling movement of the body.