One may question why it is important for a biomedical engineer to study physiology. To answer this question, we could begin by recognizing that cardiovascular disorders are now the leading cause of death in developed nations. Furthermore, to understand the pathologies or dysfunctions of the cardiovascular system, engineers must first begin to understand the physiology or proper functioning of that system. If an engineer would then like to design devices and procedures to remedy those cardiovascular pathologies, then she/he must be well acquainted with physiology.

The cardiovascular system consists of a heart, arteries, veins, capillaries, and lymphatic vessels. Lymphatic vessels are vessels, which collect extracellular fluid and return it to the circulation. The most basic functions of the cardiovascular system are to deliver oxygen, to deliver nutrients, to remove waste, and to regulate temperature.

The heart is actually two pumps: the left heart and the right heart. The amount of blood coming from the heart (cardiac output) is dependent on arterial pressure. This chapter deals with the heart and its ability to generate arterial pressure in order to pump blood.

The adult human heart has a mass of approximate 300 g. If it beats 70 times per minute, then it will beat ~100,000 times per day, ~35 million times per year, and ~3 billion times (3 X 109) during your lifetime. If each beat ejects 70 mL of blood, your heart pumps over 7000 L, or the equivalent of 1800 gal per day. That is the same as 30 barrels of blood, each and every day of your life! The lifetime equivalent work done by the heart is the equivalent of lifting 30 tons to the top of Mount Everest. All of this work is done by a very hard working 300 g of muscle that do not rest!

Figure 2.1 X-ray film showing escaped strut and disk (arrow). (Figure courtesy of Georg Thieme Verlag KG, Thorac Cardiovasc Surg. 1993;41:78)

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