When most people hear the term cardiovascular system, they immediately think of the heart. We have all felt our own heart "pound" from time to time, and we tend to get a bit nervous when this happens. The crucial importance of the heart has been recognized for a long time. However, the cardiovascular system is much more than just the heart, and from a scientific and medical standpoint, it is important to understand why this system is so vital to life.

Most simply stated, the major function of the cardiovascular system is transportation. Using blood as the transport vehicle, the system carries oxygen, nutrients, cell wastes, hormones, and many other substances vital for body homeostasis to and from the cells. The force to move the blood around the body is provided by the beating heart. The cardiovascular system can be compared to a muscular pump equipped with one-way valves and a system of large and small plumbing tubes within which the blood travels. Blood (the substance transported) is discussed in Chapter 10. Here we will consider the heart (the pump) and the blood vessels (the network of tubes).
Objective Checklist

Cardiovascular System: The Heart

• Describe the location of the heart in the body and identify its major anatomical areas on an appropriate model or diagram.
• Trace the pathway of blood through the heart.
• Compare the pulmonary and systemic circuits.
• Explain the operation of the heart valves.
• Name the functional blood supply of the heart.
• Name the elements of the intrinsic conduction system of the heart and describe the pathway of impulses through this system.
• Define systole, diastole, stroke volume, and cardiac cycle.
• Define heart sounds and murmur.
• Explain what information can be gained from an electrocardiogram.
• Describe the effect of the following on heart rate: stimulation by the vagus nerve, exercise, epinephrine, and various ions.

Cardiovascular System: Blood Vessels

• Compare and contrast the structure and function of arteries, veins, and capillaries.
• Identify the body's major arteries and veins and name the body region supplied by each.
• Discuss the unique features of special circulations of the body: arterial circulation of the brain, hepatic portal circulation, and fetal circulation.
• Define blood pressure and pulse and name several pulse points.
• List factors affecting and/or determining blood pressure.
• Define hypertension and atherosclerosis and describe possible health consequences of these conditions.
• Describe the exchanges that occur across capillary walls.

Developmental Aspects of the Cardiovascular System

• Describe briefly the development of the cardiovascular system.
• Name the fetal vascular modifications, or "fetal shunts," and describe their function before birth.
• Explain how regular exercise and a diet low in fats and cholesterol may help maintain cardiovascular health.