Muscle Flashcards
Which of the following is the primary function of the muscular system?
Generation of movement and heat
The muscular system is primarily responsible for generating movement and producing heat through muscle contractions.
What type of muscle is found in the walls of hollow organs such as the intestines
and blood vessels?
Smooth muscle
Smooth muscle is found in the walls of hollow organs and is responsible for involuntary movements such as peristalsis in the intestines and
vasoconstriction in blood vessels.
Which of the following is true about the structure of skeletal muscle fibers?
They are multinucleated.
Skeletal muscle fibers are multinucleated, meaning they have multiple nuclei per cell, which allows for the production of large amounts of protein needed for muscle contraction.
What is the role of calcium ions (Ca2+) in muscle contraction?
To bind to troponin and expose binding sites on actin
Calcium ions bind to troponin, causing a conformational change that moves tropomyosin away from the binding sites on actin, allowing myosin to
bind to actin and initiate muscle contraction.
Which of the following muscle types is under voluntary control?
Skeletal muscle
Skeletal muscle is under voluntary control, allowing conscious movement. Cardiac and smooth muscles are controlled involuntarily.
Explain the difference between isometric and isotonic muscle contractions, and provide an example of each.
Isometric contractions occur when muscle length remains the same while
tension increases, such as when holding a heavy object still.
■ Isotonic contractions occur when muscle length changes while tension
remains constant, such as when lifting a weight. In isotonic contractions,
the muscle either shortens (concentric) or lengthens (eccentric).
Describe the structure and function of the neuromuscular junction.
The neuromuscular junction is the synapse between a motor neuron and a skeletal muscle fiber. It is where the neuron releases the neurotransmitter acetylcholine, which binds to receptors on the muscle fiber’s surface, triggering an action potential that leads to muscle contraction
What are the three types of muscle tissue found in the body, and how do they differ in structure and function?
■ Skeletal muscle: Multinucleated, striated, and under voluntary control,
responsible for body movements.
■ Cardiac muscle: Striated, branched, and contains intercalated discs,
found only in the heart, and is involuntary.
■ Smooth muscle: Non-striated, spindle-shaped, and involuntary, found in
the walls of hollow organs.
Discuss the sliding filament theory of muscle contraction, including the role of
actin, myosin, and ATP.
The sliding filament theory explains how muscles contract by the sliding
of actin and myosin filaments past each other. Myosin heads bind to actin filaments, forming cross-bridges, and pull the actin filaments towards the center of the sarcomere. ATP provides the energy needed for the myosin heads to detach from actin and reattach for another power stroke, leading to muscle contraction.
How does the muscular system contribute to homeostasis, particularly in maintaining body temperature?
The muscular system contributes to homeostasis by generating heat during muscle contractions, a process known as thermogenesis. This helps maintain body temperature, especially in cold environments. Shivering, which is an involuntary contraction of muscles, is a key mechanism for generating heat when body temperature drops.
