The Cardiovascular System

Overview and Function

The cardiovascular system is a closed system composed of the heart and blood vessels. It is essential for the transport of substances throughout the body.

• Heart: Acts as a pump to propel blood.

• Blood Vessels: Serve as delivery routes for blood to reach tissues and organs.

• Main Function: Transport gases (O2, CO2), nutrients, metabolic wastes, ions, and hormones to and from cells.

Anatomy of the Heart

Location and Size

The heart is a muscular organ approximately the size of a human fist, weighing less than a pound. It is located in the thoracic cavity:

• Position: Between the lungs (laterally), in the inferior mediastinum (vertically between ribs 2 and 5).

• Orientation: The apex points toward the left hip and rests on the diaphragm; the base (where major blood vessels emerge) is directed toward the right shoulder.

Visual Representation

Figure 11.1a: The heart is centrally located within the thorax, surrounded by the lungs and protected by the rib cage. The pericardium and major vessels such as the aorta and vena cava are shown.

• Aorta: Main artery leaving the heart.

• Superior/Inferior Vena Cava: Major veins returning blood to the heart.

• Pericardium: Protective sac surrounding the heart.

• Diaphragm: Muscle beneath the heart, supporting its position.

Key Terms and Definitions

• Thoracic Cavity: The chamber of the body containing the heart and lungs.

• Mediastinum: Central compartment of the thoracic cavity, housing the heart.

• Apex: The pointed end of the heart, directed downward and to the left.

• Base: The broad, superior aspect of the heart where major vessels attach.

Example: Clinical Relevance

• Palpation of the Apex: The apex beat (point of maximal impulse) is clinically important for assessing heart function and is typically found in the fifth intercostal space at the midclavicular line.

Additional info: The anatomical position of the heart is crucial for understanding its relationship to other thoracic structures and for interpreting diagnostic imaging and physical examination findings.