Cardiovascular System: Function and Circulation

The Cardiovascular System

The cardiovascular system, also known as the circulatory system, is a vital organ system that circulates essential substances to all cells in the body. It is composed of the heart as a centralized pump, blood vessels that distribute blood throughout the body, and the blood itself for transportation of different substances. The circulatory system is divided into two separate loops: the short pulmonary circuit that exchanges blood between the heart and the lungs for oxygenation, and the longer systemic circuit that distributes blood throughout all other systems and tissues of the body. Both of these circuits begin and end in the heart.

Heart Function

The heart is a muscular organ that pumps blood throughout the body. It is divided into four chambers: two atria (right and left) and two ventricles (right and left). The heart contracts and relaxes in a process called cardiac cycles. During the contraction phase, the heart valves open, allowing blood to flow from the atria to the ventricles. During the relaxation phase, the heart valves close, preventing the backflow of blood. This process continues throughout the cardiac cycle, ensuring the continuous circulation of blood throughout the body.

Blood Vessels

Blood vessels are the network of tubes that transport blood throughout the body. They are divided into three types: arteries, veins, and capillaries. Arteries carry oxygenated blood away from the heart, while veins carry deoxygenated blood back to the heart. Capillaries are the smallest blood vessels and are the site of exchange between the blood and the surrounding tissues, allowing for the transport of nutrients, oxygen, and waste products.

Circulation

Circulation is the movement of blood throughout the body. It is regulated by several factors, including blood pressure and heart rate. The body maintains a steady mean arterial pressure by adjusting these factors in response to changes in the environment or metabolic needs. When there is a major decrease in mean arterial pressure, the body can increase heart rate, total peripheral resistance, and inotropic state to maintain blood flow.

Medical Terminology

• Cardiac output: The amount of blood the heart pumps per minute, calculated by multiplying heart rate by stroke volume.
• Stroke volume: The amount of blood pumped by the left ventricle in one contraction.
• Ejection fraction: The percentage of blood ejected from the left ventricle with each heartbeat.
• Total peripheral resistance: The resistance to blood flow in the systemic arterial network.
• Inotropic state: The force of heart muscle contraction.
• Chronotropic state: The rate of heart muscle contraction.
• Dromotropic state: The rate of electrical conduction through the heart.
• Blood pressure: The force exerted by blood on the walls of blood vessels.
• Pulse pressure: The difference between systolic and diastolic blood pressure.
• Mean arterial pressure: The average blood pressure throughout the cardiac cycle.
• Central venous pressure: The pressure within the central blood vessels.

Cardiovascular Diseases

Cardiovascular diseases (CVDs) are a group of conditions that affect the heart and blood vessels. They include coronary artery disease, heart failure, hypertension, and peripheral artery disease. CVDs are a leading cause of morbidity and death worldwide, and ongoing research is aimed at enhancing early detection, risk reduction, and improving treatment options.

References

• Cardiovascular physiology - Wikipedia
• Circulatory system | Functions, Parts, & Facts | Britannica
• Updates in the Management of Coronary Artery Disease: A Review
• Circulatory system: Structure, function, parts, diseases - Kenhub