Inferior tracheobronchial lymph nodes, esophagus, vagus nerve, descending aorta, azygos and hemiazygos veins, and diaphragm muscle

Inferior vena cava, pulmonary trunk, oval fossa, trachea, and thyroid

Right lung, phrenic nerve, left atrium, larynx, brachiocephalic veins, brachial plexus, ascending aorta, tracheal lymph nodes, and inferior vena cava

Pulmonary arteries, right bronchus, thoracic duct, superior vena cava, and liver

Pulmonary arteries, aorta, brachiocephalic artery, coronary arteries

Superior and inferior vena cava, pulmonary arteries, thoracic duct

Carotid arteries, jugular veins, aorta, pulmonary veins

Superior and inferior vena cava, pulmonary veins, coronary sinus

Myocardium

Epicardium

Endocardium

Pericardial cavity

To regulate hormonal secretion (endocrine function), distribute oxygen to tissues (respiratory function), and control blood glucose levels via lymphatic capillaries (glycoregulatory function).

To drain interstitial fluid (drainage function), absorb dietary lipids (metabolic function), and support immune surveillance through lymphocyte transport (immune function).

To circulate nutrients from the digestive tract (nutritive function), remove carbon dioxide from peripheral tissues (excretory function), and regulate neural conduction (neuromodulatory function).

To generate red blood cells (hematopoietic function), detoxify metabolic waste (detoxification function), and transmit electrical signals between organ systems (integrative function).

To regulate blood flow between the heart chambers and control valve opening through active muscular contraction.

To initiate and coordinate cardiac electrical impulses that ensure synchronous contraction of the myocardium.

To protect the heart, limit its movement within the thoracic cavity, and prevent overdistension by providing a frictionless double-layered sac.

To maintain intracardiac pressure by controlling vascular tone and secreting fluid to regulate systemic blood volume.