20 Questions
What gives individual cardiac muscle fibers a 'stair-step' appearance?
Branching
What is the typical length of a cardiac muscle fiber?
50–100μm
What is the approximate diameter of a cardiac muscle fiber?
14μm
What connects the ends of cardiac muscle fibers to neighboring fibers?
Intercalated discs
What occupies 25% of the cytosolic space in a cardiac muscle fiber?
Mitochondria
What is the primary function of intercalated discs in cardiac muscle fibers?
To hold the fibers together and allow muscle action potentials to conduct
What is the approximate percentage of cytosolic space occupied by mitochondria in cardiac muscle fibers?
25%
How do cardiac muscle fibers differ from skeletal muscle fibers in terms of length and shape?
Shorter in length and less circular in transverse section
What is the primary role of gap junctions in cardiac muscle fibers?
Allow muscle action potentials to conduct from one muscle fiber to its neighbors
What is the typical diameter of a cardiac muscle fiber?
About 14μm
What is the approximate percentage of cytosolic space occupied by mitochondria in cardiac muscle fibers?
25%
What is the typical length of a cardiac muscle fiber?
50–100m
What is the primary function of intercalated discs in cardiac muscle fibers?
To hold the muscle fibers together
What is the approximate diameter of a cardiac muscle fiber?
14m
What gives individual cardiac muscle fibers a 'stair-step' appearance?
Branching
What is the primary function of intercalated discs in cardiac muscle fibers?
To hold the fibers together
What is the significance of the larger and more numerous mitochondria in cardiac muscle fibers?
They provide energy for constant muscle contraction
What allows the entire myocardium of the atria or the ventricles to contract as a single, coordinated unit?
Gap junctions
What is the approximate length of a typical cardiac muscle fiber?
50–100μm
What is the characteristic feature of the ends of cardiac muscle fibers connecting to neighboring fibers?
Irregular transverse thickenings called intercalated discs
Test your knowledge of the unique characteristics of cardiac muscle fibers with this quiz. Explore the differences in length, shape, and structure compared to skeletal muscle fibers, and understand the distinct features of cardiac muscle at the cellular level.
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