The cardiovascular system delivers dietary nutrients and oxygen throughout the body and collects metabolic wastes for removal by the kidneys. Interstitial fluid is collected by lymphatic vessels and returned to the circulation. Primary vessels are formed by vasculogenesis, while angiogenesis refers to expansion and remodeling of the vascular system.
Blood and lymphatic vessels are lined with a single layer of endothelial cells which mediate nutrient exchange, respond to blood-borne factors, and are the initial contact site for circulating immune cells during inflammation. Arterial vessels are surrounded by a vascular smooth muscle layer which provides physical support to withstand pulsatile blood flow from the heart and also serves to regulate blood pressure through contraction and relaxation. Veins and lymphatic vessels contain valves to endure directional fluid flow. The elastic lamina and adventitia layers provide additional support to blood and lymphatic vessels.
The cardiovascular system is a critical transporter of materials throughout the body. Endocrine glands secrete peptide and small molecule hormones into the circulation to regulate processes in distant tissues of the body. Immune cells circulate in the blood and extravasate through the vascular endotheium to carry out immune reactions at inflammatory sites. They subsequently traffic through lymphatic vessels to regional lymph nodes and return to the circulation to support systemic immunity.
Physical damage to the vasculature triggers activation of the coagulation cascade to induce clot formation and minimize blood loss. Metastasis of solid tumors relies on the circulation for dissemination of tumor cells to secondary sites in malignant cancer. In addition, multiple cardiovascular diseases such as atherosclerosis, stroke, hypertension, venous thrombosis, diabetes, cardiomyopathy, and arrythmias are some of the most widespread health concerns in our society.