Blood is a vital connective tissue that serves as the body's transport system. It consists of four main components: plasma, red blood cells, white blood cells, and platelets. Blood flows through vessels, carrying oxygen, nutrients, and waste products while maintaining the body's internal balance.
Blood is a vital connective tissue that flows through our circulatory system. It serves as the body's transportation network, carrying oxygen from the lungs to tissues, delivering nutrients from the digestive system, and removing metabolic waste products. This amazing fluid is composed of various specialized cells suspended in a liquid matrix called plasma.
Blood composition can be broken down by volume percentages. Plasma makes up fifty-five percent and serves as the liquid matrix containing dissolved substances. Red blood cells comprise forty-four percent with their distinctive biconcave shape maximizing surface area. White blood cells and platelets each make up less than one percent but play crucial roles in immunity and clotting respectively.
Red blood cells, or erythrocytes, are the most abundant cells in blood. Their unique biconcave disc shape maximizes surface area for gas exchange while allowing flexibility to squeeze through tiny capillaries. They lack a nucleus, providing more space for hemoglobin, the iron-containing protein that binds oxygen. Each red blood cell lives about one hundred twenty days before being recycled by the spleen.
White blood cells are the immune system's defenders. Neutrophils are the first responders, quickly arriving at infection sites. Lymphocytes include T-cells and B-cells that provide specific immunity and memory. Monocytes mature into macrophages that engulf pathogens and debris. Eosinophils combat parasites and mediate allergic reactions, while basophils release histamine during inflammatory responses.
Blood serves three primary functions: transportation, regulation, and protection. It transports oxygen, carbon dioxide, nutrients, and waste products throughout the body. It regulates body temperature, pH levels, and fluid balance. For protection, it provides immunity through white blood cells and prevents blood loss through clotting mechanisms. The complete circulation cycle takes approximately sixty seconds, flowing from the heart through arteries to capillaries where gas and nutrient exchange occurs, then returning through veins back to the heart.
Red blood cells, or erythrocytes, are highly specialized for oxygen transport. Their unique biconcave disc shape provides maximum surface area while maintaining flexibility to squeeze through the smallest capillaries. Without a nucleus, they have more space for hemoglobin molecules. Each cell contains about 280 million hemoglobin molecules that bind oxygen in the lungs and release it to tissues. Hemoglobin changes color from blue when deoxygenated to bright red when carrying oxygen. These cells are produced in bone marrow and live for 120 days before being recycled by the spleen.
White blood cells are the immune system's specialized defenders, each with unique functions. Neutrophils are the most abundant, acting as first responders that quickly engulf bacteria and cellular debris. Lymphocytes include B-cells that produce antibodies and T-cells that coordinate immune responses and maintain immunological memory. Monocytes circulate in blood and mature into macrophages in tissues, performing large-scale phagocytosis. Eosinophils combat parasitic infections and mediate allergic reactions, while basophils release histamine and other mediators during inflammatory responses.