CardiovascularSystem - THE CARDIOVASCULAR SYSTEM Beyond a...

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1 THE CARDIOVASCULAR SYSTEM Beyond a distance of a few cell diameters, diffusion (the passive movement of materials from a region of higher concentration to a region of lower concentration) is not nearly fast enough to meet the metabolic needs of the cells, which comprise our bodies. For multicellular organisms such as ourselves, some mechanism other than diffusion is needed to transport molecules rapidly over the extremely long distances between the internal cells of the body and the body's surface and between the various tissues and organ systems. This function is performed by the blood, the set of interconnected tubes through which the blood flows (blood vessels), and the pump (the heart) that generates the pressure to produce the flow. The heart, blood, and blood vessels collectively are termed the cardiovascular system . Thus, the function of the cardiovascular system is to contribute to homeostasis by transporting needed materials from one part of the body to another. Recall that homeostasis refers to the maintenance of a relatively constant internal environment . The internal environment is the fluid, called interstitial fluid that surrounds each of the cells in the body. Homeostasis is a condition that is mandatory for normal and proper cell function. When homeostasis is disrupted, disease and/or death can result. Some of the major transport functions of the cardiovascular (CV) system are listed below : 1. Transports nutrient molecules from the digestive system (where these molecules enter the body) to the cells of the body. 2. Transports oxygen from the lungs (where O 2 enters the body from the atmosphere) to the cells of the body. 3. Transports CO 2 from the cells of the body (where it is produced by the Kreb's cycle) back to the lungs where it is eliminated from the body to the atmosphere. 4. Transports other metabolic waste products (e.g., urea) from the body's cells to the kidneys for elimination. 5. Transports hormones from the endocrine glands where they are produced to their target cells located throughout the body. 6. Transports white blood cells and antibodies throughout the body to help protect it from invasion by foreign organisms (bacteria, viruses, parasites) 7. Helps regulate body temperature by transporting heat from one location in the body to another. OVERVIEW OF THE CARDIOVASCULAR SYSTEM 1. Study and completely understand Fig. 18.5 in Marieb and the figure on the next page!!!!!! 2. Note that the circulatory system is actually two separate circulations, each originating and terminating in the heart. This means that the heart is actually two separate pumps, one pumping blood through one circuit and the other pumping blood through the other circulation. The two circuits are arranged in series relative to one another (i.e., end to end).
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