Chapter 17: The Heart

Introduction to the Heart

The heart is a muscular organ responsible for pumping blood throughout the body via the circulatory system. This process ensures the delivery of oxygen and nutrients to tissues and the removal of waste products. Understanding the heart's anatomy and physiology is essential for comprehending its role in maintaining homeostasis.

• Key Function: Transportation of blood through the circulation.

• Importance: Supports cellular metabolism and systemic health.

• Example: The heart beats approximately 100,000 times per day, circulating about 7,000 liters of blood.

Location of the Heart in the Thoracic Cavity

Position and Surrounding Structures

The heart is located in the thoracic cavity, specifically within the mediastinum, which is the central compartment of the chest. It is flanked by the lungs and rests on the diaphragm, with its apex pointing downward and to the left.

• Mediastinum: The area between the lungs where the heart is situated.

• Major Landmarks: The heart lies posterior to the sternum and anterior to the vertebral column.

• Surrounding Structures: Includes the ribs, diaphragm, right and left lungs, and major blood vessels such as the aorta and superior vena cava.

• Orientation: The base of the heart is superior, while the apex is inferior and leftward.

• Example: In the anterior view, the heart is seen nestled between the lungs, with the diaphragm forming its inferior boundary.

Main Anatomical Features (Anterior View)

• Superior Vena Cava: Returns deoxygenated blood from the upper body to the right atrium.

• Aorta: The main artery carrying oxygenated blood from the left ventricle to the body.

• Pulmonary Trunk: Carries deoxygenated blood from the right ventricle to the lungs.

• Diaphragm: The muscular partition separating the thoracic and abdominal cavities, supporting the heart's inferior aspect.

• Right and Left Atrioventricular Sulci: Grooves marking the boundaries between the atria and ventricles.

Additional info:

• The heart is roughly the size of a closed fist and weighs between 250-350 grams in adults.

• The pericardium is a double-walled sac that encloses the heart, providing protection and reducing friction during contraction.