The dorsal surface of the heart lies near the bodies of the vertebrae, and its anterior surface sits deep to the sternum and costal cartilages. Within the mediastinum, the heart is separated from the other mediastinal structures by a tough membrane known as the pericardium, or pericardial sac, and sits in its own space called the pericardial cavity. Figure 19.2 shows the position of the heart within the thoracic cavity. The human heart is located within the thoracic cavity, medially between the lungs in the space known as the mediastinum. In order to understand how that happens, it is necessary to understand the anatomy and physiology of the heart. Over one year, that would equal 10,000,000 liters or 2.6 million gallons of blood sent through roughly 60,000 miles of vessels. This would be equal to 5.25 liters of fluid per minute and approximately 14,000 liters per day. Each of the major pumping chambers of the heart ejects approximately 70 mL blood per contraction in a resting adult. If one assumes an average rate of contraction of 75 contractions per minute, a human heart would contract approximately 108,000 times in one day, more than 39 million times in one year, and nearly 3 billion times during a 75-year lifespan. The vital importance of the heart is obvious.
Trace the pathway of oxygenated and deoxygenated blood thorough the chambers of the heart.Identify the veins and arteries of the coronary circulation system.Compare systemic circulation to pulmonary circulation.Relate the structure of the heart to its function as a pump.Identify the tissue layers of the heart.Describe the internal and external anatomy of the heart.Describe the location and position of the heart within the body cavity.By the end of this section, you will be able to:
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