The cardiovascular system is one of the most important systems in the human body. It interacts with the other body systems and is divided into two main parts:
- The circulatory system, which consists of the heart (acting as a pump) and the blood vessels
- The lymphatic system, which comprises the lymph nodes and vessels, through which colourless lymph flows.
The circulatory system consists of the heart, arteries and veins, and functions to pump the blood to all other the other body systems, providing the body with nutrients and oxygen and removing toxins and waste. For this reason, the circulation is further divided into two parts (Fig.1): - The pulmonary circulation.
- The systemic circulation.
Figure.1: The circulation of the cardiovascular system (Drake et al, 2009).
The heart is pyramidal in shape will its apex projecting forwards and downwards to the left side, while its base faces in the opposite, posterior direction. It is located in the middle mediastinum in the thoracic cavity and is covered by a fibroserous sac called the pericardium. This sac has layers: the fibrous pericardium and the serous pericardium, which is further divided into parietal and visceral layers. Blood vessels and nerves supply the pericardial sac (Fig.2):
- Arteries: branches from the internal thoracic, pericardiacophrenic, musculophrenic, and inferior phrenic arteries and the thoracic aorta.
- Veins: vessels from the pericardium enter the azygos system of veins, the internal thoracic and superior phrenic veins.
- Nerves: branches arise from the vagus nerve [X], the sympathetic trunks and the phrenic nerves.
Figure.2: The vessels and nerves which supply the pericardium (Drake et al, 2009).
In addition, the sides of the heart can be considered as four surfaces (Fig.3):
- The inferior surface of the heart is known as the diaphragmatic surface.
- The anterior surface is known as the sternocostal surface.
- The right and left sides are known as the right and left pulmonary surfaces.
Figure.3: The sides of the heart and names of the surfaces (Drake et al, 2009).