How can you distinguish between cardiac and smooth muscle?
Cardiac muscle cells are located in the walls of the heart, appear striped (striated), and are under involuntary control. Smooth muscle fibers are located in walls of hollow visceral organs (such as the liver, pancreas, and intestines), except the heart, appear spindle-shaped, and are also under involuntary control.
Why do smooth muscle fibers in cross section have different diameters and why do some of these fail to show nuclei?
Why do smooth muscle fibers in cross section have different diameters and why do some of these fail to show nuclei? Smooth muscle cells have tapered ends. Since the cells interdigitate different diameters would be revealed in a particular plane of section and the plane of section does not always go through the nucleus.
Why do the two layers of smooth muscle have different appearance in the cross section?
The appearance of smooth muscle varies dramatically, depending on the orientation of the fibers with respect to the plane of section. In this section, the circular muscle fibers are cut longitudinally, while the longitudinal muscle fibers are cut in cross section (transversely).
How is the appearance of smooth muscle tissue different if you observe a cross sectional view of the tissue rather than a longitudinal view?
The nucleus is also elongated, often cigar-shaped. Note especially the appearance of smooth muscle nuclei. When cut in longitudinal section, smooth muscle nuclei appear very long and sometimes wiggly (due to contraction). In cross-sectioned smooth muscle, only a fraction of the fibers display nuclei.
How does cardiac muscle differ from the other types of muscle?
Cardiac muscle differs from skeletal muscle in that it exhibits rhythmic contractions and is not under voluntary control. The rhythmic contraction of cardiac muscle is regulated by the sinoatrial node of the heart, which serves as the heart’s pacemaker.
Are cardiac muscles also smooth muscles?
Cardiac muscle (also called heart muscle or myocardium) is one of three types of vertebrate muscle tissue, with the other two being skeletal muscle and smooth muscle. It is involuntary, striated muscle that constitutes the main tissue of the wall of the heart….
How does cardiac muscle differ from skeletal muscle?
What is the difference between cardiac and skeletal muscle contraction mechanism?
The major difference between cardiac and skeletal muscle is modulation of the extent of thin filament activation. Force development must be controlled mainly at the cellular level in cardiac muscle because each cardiac cell is activated on each beat.
What are two unique features of cardiac muscle that can be seen in longitudinal section only?
A. In longitudinal sections, observe:
- Intercalated discs which are dark lines which cross the cell transversely.
- The nucleus is centrally located in a fiber.
- Longitudinal striping due to myofibrils can sometimes be seen.
How is heart muscle different from skeletal muscle?
Which of the following characteristics is unique to smooth muscle?
Four characteristics define smooth muscle tissue cells: they are involuntarily controlled, not striated, not branched, and singly nucleated. The unconscious regions of the brain control visceral muscle through the autonomic and enteric nervous systems.
What was one unique characteristic about cardiac muscle that was different from both of the other types of muscle tissue could you see this in the slide image?
Cardiac muscle is only found in the heart. Its fibers are longer than they are wide, and they are striated, like skeletal muscle fibers. But, unlike skeletal muscle fibers, cardiac muscle fibers have distinct ends to them, called intercalated discs. These are dark lines that run from one side of the fiber to the other.