22.1:
Overview of the Cardiovascular System
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The cardiovascular or circulatory system comprises the blood, the heart, and the blood vessels. Blood is a specialized fluid comprising cells in a liquid extracellular matrix. It transports gases, nutrients, hormones, and cellular waste products throughout the body. The heart is a muscular pump with four chambers — two atria that receive blood and two ventricles that pump out blood for distribution. It is connected to a closed circuit of blood vessels, forming an intricate network for blood transport. This network is divided into two separate circuits: pulmonary and systemic. The oxygenation occurs in the pulmonary circuit, transporting blood from the heart to the lungs, while systemic circulation distributes oxygenated blood from the heart to the other tissues. Both these circuits comprise three types of blood vessels: arteries, veins, and capillaries. The arteries take blood away from the heart, while veins return blood to the heart. Arteries and veins are connected via microvessels called capillaries, whose thin walls facilitate the exchange of substances between the blood and the interstitial tissue fluid.
22.1:
Overview of the Cardiovascular System
The cardiovascular system is a vital transportation system in the body. It comprises the heart and blood vessels and facilitates the exchange of gases, nutrients, and waste products.
Heart
The heart is the central pump of the cardiovascular system that circulates blood throughout the body. It comprises two atria receiving the blood and two ventricles pumping blood out of the heart. Their rhythmic contractions, called heartbeats, ensure that blood flow remains continuous.
Blood Vessels
Blood vessels are like pipelines, carrying blood to all body parts. There are three types: arteries, veins, and capillaries.
- • Arteries: Arteries are muscular, elastic blood vessels that transport oxygenated blood from the heart to different tissues and organs, withstanding the high pressure generated by the heart's pumping action.
- • Veins: Veins have thinner walls than arteries but contain valves to prevent the backward flow of deoxygenated blood back to the heart, acting as the return routes of the cardiovascular system.
- • Capillaries: Capillaries form a network throughout the body, allowing for nutrient and gas exchange with surrounding cells. Oxygen and nutrients diffuse into the tissues while carbon dioxide and other waste products are removed.
Double Circulation
Double circulation involves two loops: pulmonary circulation and systemic circulation.
- • Pulmonary Circulation: This loop carries deoxygenated blood from the heart to the lungs. The heart pumps the blood to the lungs, picking up oxygen and releasing carbon dioxide.
- • Systemic Circulation: This loop transports oxygenated blood from the heart to the rest of the body's tissues and organs. The tissues utilize the oxygen and nutrients, and the deoxygenated blood is collected and sent back to the heart through veins.