adaptations of cardiac muscles and striated muscle fibers Flashcards
What is the main function of muscle tissue?
Muscle tissue is contractile, meaning it can shorten in length, generating a pulling force that can cause movement.
Why do muscles work in antagonistic pairs?
Muscles work in antagonistic pairs because the contraction of one muscle causes the lengthening of another, allowing controlled movement in opposite directions.
What is striated muscle and where is it found?
Striated muscle is composed of long, unbranched cylindrical muscle fibres arranged in parallel. It is found in skeletal muscles attached to bones and is visible under a light microscope due to its striped appearance.
What is the structure of skeletal muscle fibres?
Skeletal muscle fibres are long and have a single plasma membrane but contain multiple nuclei. These fibres are much longer than typical cells and are formed by the fusion of embryonic muscle cells.
What are myofibrils in skeletal muscle fibres?
Myofibrils are parallel cylindrical structures within each muscle fibre. They have alternating light and dark bands and a Z-line at the center of the light bands, responsible for muscle contraction.
How do cardiac muscle cells differ from skeletal muscle cells?
Cardiac muscle cells are shorter and typically have one nucleus. They also have intercalated discs that connect cells at their ends and allow rapid propagation of electrical signals for coordinated contraction.
What are intercalated discs in cardiac muscle and what is their function?
Intercalated discs are specialized junctions between cardiac muscle cells. They allow electrical signals to pass quickly between cells, ensuring that when one cell contracts, all cells in the heart contract together, enabling synchronized heartbeats.
Why are cardiac muscle cells branched?
Cardiac muscle cells are branched to form a network that allows for efficient signal transmission between cells via intercalated discs, ensuring coordinated contraction of the heart muscle.
How does the structure of skeletal muscle contribute to its function?
The long, cylindrical shape and multiple nuclei of skeletal muscle fibres allow them to contract efficiently. The parallel arrangement of fibres ensures coordinated and powerful muscle contractions for movement.
Why is it debated whether a muscle fibre should be considered a cell?
It is debated whether a muscle fibre should be considered a cell because it has multiple nuclei (instead of just one) and can be up to 30mm in length, much larger than typical cells (which are usually less than 0.03mm in length).
What is the role of myofibrils in muscle contraction?
Myofibrils contain light and dark bands that are responsible for muscle contraction. The sliding of actin and myosin filaments in the myofibrils shortens the muscle fibre, leading to contraction.
How does cardiac muscle contraction work in the heart?
When one cardiac muscle cell is stimulated to contract, the intercalated discs allow the electrical signal to rapidly spread to adjacent cells. This ensures that all cells in the heart contract together, causing the heart to pump blood effectively.
