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Introduction

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High-Yield Terms

  • Artery: blood vessels that carry blood away from the heart

  • Vein: blood vessels that carry blood toward the heart

  • Capillary: are the smallest vessels and constitute the vessels of the microcirculation

  • Atherogenic: relating to the processes of initiating, increasing, and/or accelerating atherogenesis

  • Atheroma: represents result of the accumulation of leukocytes (mostly macrophages), lipids, and debris causing swelling of the arterial wall

  • Metabolic syndrome: a disorder that defines a combination of metabolic and cardiovascular risk determinants that leads to coronary artery disease (CAD)

  • Atherosclerosis: refers to the condition in which wall of larger arteries and veins thickens as a result of the accumulation of fatty material, cells, and extracellular matrix components

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The Cardiovascular System

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The cardiovascular system, also referred to as the circulatory system, is comprised of the heart and the blood vessels (Figure 48-1). The heart has 2 separate sides and each side has 2 chambers. The upper chamber on each side of the heart is called an atrium and the bottom chamber on each side is called a ventricle. The ventricles are the chambers that pump the blood with each contraction. One side of the heart (left ventricle) is designed to propel the oxygenated blood into the systemic circulation. Within the tissues the erythrocytes and the blood exchange O2 for the CO2 generated through metabolic processes. The other side of the heart (right ventricle) is designed to propel deoxygenated blood into the pulmonary circulation where the blood becomes oxygenated in the alveoli of the lungs. Within the lungs the CO2 is expelled during respiration and the erythrocyte hemoglobin becomes fully oxygenated once again.

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FIGURE 48-1:

Diagram of the cardiovascular system. Mescher AL. Junqueira's Basic Histology Text and Atlas, 13th ed. New York, NY: McGraw-Hill; 2013.

Graphic Jump Location
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The vasculature is composed of the arteries, veins, and the capillaries (Figure 48-2). Within all tissues the capillaries form a fine meshwork of tubules called the microvasculature. The capillaries are very small, thin-walled blood vessels where the exchange of gases, nutrients, and waste takes place between the cells and the blood. Arteries and veins are composed of a trilaminar structure. The inner layer of the vessels is called the intima (also called tunica intima) and is composed of a monolayer of endothelial cells. The endothelial cells are in continuous contact with the blood and as such these cells are the first to respond to the changing composition and environment of the blood. Cardiovascular disorders, such as atherosclerosis, result from the consequences of abnormal interactions between components and cells in the blood and the endothelial cell layer of the vasculature.

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FIGURE 48-2:

Schematics of the structures of various types of blood vessels. A. Capillaries consist of an endothelial tube in contact with a discontinuous population of pericytes. B. Veins typically have ...

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