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OBJECTIVES

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The student understands the homeostatic role of the cardiovascular system, the basic principles of cardiovascular transport, and the basic structure and function of the components of the system:

  • Defines homeostasis.

  • Identifies the major body fluid compartments and states the approximate volume of each.

  • Lists 3 conditions, provided by the cardiovascular system, that are essential for regulating the composition of interstitial fluid (i.e., the internal environment).

  • Predicts the relative changes in flow through a tube caused by changes in tube length, tube radius, fluid viscosity, and pressure difference.

  • Uses the Fick principle to describe convective transport of substances through the CV system and to calculate a tissue’s rate of utilization (or production) of a substance.

  • Identifies the chambers and valves of the heart and describes the pathway of blood flow through the heart.

  • Defines cardiac output and identifies its 2 determinants.

  • Describes the site of initiation and pathway of action potential propagation in the heart.

  • States the relationship between ventricular filling and cardiac output (the Starling law of the heart) and describes its importance in the control of cardiac output.

  • Identifies the distribution of sympathetic and parasympathetic nerves in the heart and lists the basic effects of these nerves on the heart.

  • Lists the 5 factors essential to proper ventricular pumping action.

  • Lists the major different types of vessels in a vascular bed and describes the morphological differences among them.

  • Describes the basics and functions of the different vessel types.

  • Identifies the major mechanisms in vascular resistance control and blood flow distribution.

  • Describes the basic composition of the fluid and cellular portions of blood.

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EVOLUTION AND HOMEOSTATIC ROLE OF THE CARDIOVASCULAR SYSTEM

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All living organisms require outside energy sources to survive. Indeed, Darwin deduced his evolutionary concepts largely on observations of external adaptations that evolved in different organisms to exploit particular unique sources of “food” energy. Clearly one strong evolutionary force has been to maximize the ability to obtain outside energy.

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In the big picture of “survival of the fittest,” equally important to obtaining outside energy is making efficient use of it once it is obtained. Therefore, we contend that developing energy-efficient mechanisms to accomplish all internal tasks necessary for successful life has also been a strong evolutionary force and probably applies to all “internal” processes.

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In this text, we focus on how the design and operation of the human cardiovascular system has evolved to accomplish its essential tasks with a minimum of energy expenditure.

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Image not available.A 19th-century French physiologist, Claude Bernard (1813–1878), first recognized that all higher organisms actively and constantly strive to prevent the external environment from upsetting the conditions necessary for life within the organism. Thus, the temperature, oxygen concentration, pH, ionic composition, osmolarity, and many other important variables of our internal environment are closely controlled. This process of maintaining the “constancy” of our internal environment has come to be known as homeostasis. To aid ...

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