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Circulatory System. The Need for Circulation. The need for circulation arose as an evolutionary adaptation to increasing body size . The circulatory system delivers oxygen, nutrients and hormones, and it transports immune cells and metabolic wastes. Types of Circulatory Systems. Blood.
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The Need for Circulation • The need for circulation arose as an evolutionary adaptation to increasing body size. • The circulatory system delivers oxygen, nutrients and hormones, and it transports immune cells and metabolic wastes
Blood • Human body contains 4-5 L of blood • Blood is a connective tissue with 2 main components: Cells and liquid; the liquid is an intercellular matrix called plasma • Blood cells are manufactured in the bone marrow
Plasma • 90% water • Contains many dissolved or suspended substances: Glucose, oxygen, proteins, minerals, vitamins, carbon dioxide, and dissolved ions (Na+, K+, Ca2+, Cl-, HCO3-). • Proteins and sodium ions in plasma are necessary to create an osmotic gradient, which causes water to enter the bloodstream.
Blood Cells • Red Blood Cells (erythrocytes) • Biconcave disk shaped cells that contain hemoglobin, used for transporting oxygen and carbon dioxide. • Lifespan:120 days • Between 2-3 million produced every second • Contain surface proteins (antigens) that determine blood type
Blood Cells (cont) • White Blood Cells (leukocytes) • Neutrophils, basophils, and eosinophils: contain chemicals to kill harfulmicroorgansism • Macrophages: use phagocytosis to engulf bacteria, harmful substances, and dead cells • T-Cells: kill virus-infected cells • B-Cells: produce antibodies against bacteria
Blood Cells (cont) • Platelets: Used for blood clotting • When blood vessels break, platelets release chemicals that cause platelets to sticks to collagen proteins in the blood to form temporary clot • Fibrinogen converted to fibrin, by clotting factors, to form permanent clot
Blood Typing • Blood type antigens and Rh antigens determine the blood type of an individual • If Rh antigens are present, individual is Rh positive