Cardiovascular system

Cardiovascular system

• is vital for the functioning of all organs, ensuring the delivery of oxygen, nutrients and signaling molecules, such as hormones to tissues, and evacuating carbon dioxide and metabolic products from them;
• includes the circulatory system and associated lymphatic vessel system;
• the closed circulatory system due to the rhythmic contractile activity of the heart provides blood circulation, and the lymphatic vessel system — a unidirectional flow of lymph and interstitial fluid from tissues into the blood and further to the heart;
• the cavities of the heart and the lumen of all vessels are lined with a single layered squamous epithelium — endothelium, which has antithrombotic properties.

Circulatory system

• includes four-chambered heart, arteries, vessels of the microcirculatory bed and veins;
• in the wall of heart, which develops from embryonic vessels distinguished three membranes: endocardium (inner), myocardium (middle) и epicardium (outer, visceral leaflet of the pericardium);
• the walls of arteries and veins also have three layers: inner (intima), middle (media) and outer (adventitia);
• microcirculatory bed is formed by small vessels (with a diameter of less than 100 microns) directly involved in blood supply and tissue nutrition.

Heart

• human's and mammalian's has four chambers — right and left atria and the right and left ventricles;
• between the atria and ventricles, as well as in the area of departure from the heart of large arteries (aorta, pulmonary trunk), there are heart valves, that prevent the reverse flow of blood;
• the main functional component of the heart is its tunica media — myocardium, whose coordinated contractions determine the movement of blood in the cavities of the heart and its movement in the blood vessels;
• regulation of myocardial contractile activity is carried out by cardiac conduction system, which includes two nodes, containing specialized cardiac muscle cells that generate electrical impulses (pacemaker cells), and a system of conductive cardiomyocytes, that transmit stimuli to contractile myocytes.

Heart wall

Heart valves