Muscle tissue makes movement possible through cells that respond to stimuli and generate force. This lesson compares the three muscle tissue types—skeletal, cardiac, and smooth—and connects their structures to their functions.
When a muscle is attached between movable structures, such as bones, its contraction can move those structures. Muscle movement may be voluntary, under conscious control, or involuntary, occurring without conscious control. Choosing to open a book is voluntary; the pupil’s response to bright light is involuntary.
All flashcards
What are excitability and contractility?
Excitability is the ability of a muscle cell to respond to a stimulus. Contractility is its ability to shorten and generate a pulling force.
What are the main features of skeletal muscle?
Skeletal muscle is usually attached to bones and supports voluntary movement. Its long fibers are striated and contain many peripheral nuclei; contraction also produces heat.
What are intercalated discs, and why are they important?
Intercalated discs are specialized junctions connecting cardiac muscle cells. Their anchoring junctions hold cells together, while their gap junctions help electrical signals spread so contractions can be coordinated.
How is smooth muscle structured and where is it found?
Smooth muscle consists of short, spindle-shaped cells with one nucleus and no evident striations. It occurs in the walls of organs and passageways, including the digestive tract, airways, and arteries.
What is the quickest microscope clue for distinguishing skeletal from smooth muscle?
Look for striations and nuclei. Skeletal muscle has visible striations and many nuclei; smooth muscle lacks evident striations and generally has one nucleus per cell.
Quiz questions
What does contractility describe in muscle tissue?Answer: The ability to shorten and generate pulling force.
Which description matches skeletal muscle fibers?Answer: Long cylindrical fibers with striations and many peripheral nuclei.
What do gap junctions in cardiac intercalated discs do?Answer: They allow electrical signals to pass between neighboring cardiomyocytes.
Which tissue has short, spindle-shaped cells, usually with one nucleus and no evident striations?Answer: Smooth muscle.
Which description matches cardiac muscle cells?Answer: Short, branched, striated cells, usually with one central nucleus.
Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.