The length-tension relationships, hyperbolic velocity-load relationships, power output curves, and ability to resist imposed loads are comparable to those of skeletal muscle. Shortening velocities and ATP consumption rates are very low in smooth muscle, in keeping with expression of a myosin isoform with low activity. Smooth muscles also have the unusual ability to alter velocity-stress relationships, which reflects regulation of both the number of active cross-bridges (determining force) and their average cycling rates for a given load (determining velocity).
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8. Smooth muscle is also a synthetic and secretory cell with a major role in formation of the extensive extracellular matrix that surrounds and links the cells. Cellular hypertrophy occurs in response to physiological needs, and smooth muscle cells retain the potential to divide.
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SECTION 4The Cardiovascular System ACHILLES J. PAPPANO AND WITHROW GIL WIER
Overview of Circulation Regulation of the Heart and Vasculature
Chapter 16 Elements of Cardiac Function Chapter 19 Integrated Control of the Chapter 17 Cardiovascular System Properties of the Vasculature
Upon completion of this chapter, the student should be able to answer the following questions: 1.
How does the arrangement of heart and vessels enable unidirectional flow of well-oxygenated blood to the body?
2.
What is the advantage of the reciprocal relation between blood flow velocity and vascular cross-sectional area?
3.
How do the differing compositions (smooth muscle, fibrous and elastic tissue) of blood vessels contribute to their respective functions?