BIOL 100 Chapter 11: Blood

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University of Nevada - Las Vegas
Biological Sciences
BIOL 100
Michael Webber

11.1 Functions of Blood • blood is also called the river of life • functions of blood include: • transportation • protection • regulation 11.2 Composition of Blood • the liquid matrix is called plasma, and the cellular elements are collectively referred to as the formed elements • Plasma: • plasma-a straw colored liquid that makes up about 55% of blood • is a medium for transporting materials in the blood • examples: • nutrients • ions • gases • every hormone • carries away cellular waste • most of the dissolved substances (solutes) in the blood are plasma proteins • plasma proteins- make up 7% to 8% of plasma; help balance water flow between the blood and the cells • 3 categories of plasma proteins: • albumins • make up more than half of the plasma proteins • water balancing ability in blood • globulins • various functions; • Example: • transportation, antibodies • clotting proteins • Formed Elements: 1 of 1 • Consists of: • red blood cells • white blood cells • platelets • stem cells- divide and give rise to all the formed elements • all formed elements originate from the stem cell in the red bone marrow Typpe of Forme ed Cell Function Description Number of Life Span Elemmeent Cells/mm^3 Red Blood Cells transport oxygen biconcave disk, no 4-6 million about 120 days (RBCs; and carbon dioxide nucleus erythrocytes) Neutrophils (a typeconsume bacteria multilobed 3,000-7,000 6-72 hours of white blood cellby phagocytosis nucleus, clear- staring cytoplasm, inconspicuous granules Eosinophils (a type consume antibody- large, pink-staining100-400 8-12 days of white blood cellantigen complex granule in by phagocytosis: cytoplasm; bilobed attack parasitic nucleus worms Basophils (a type Release histamine, large, purple- 20-50 3-72 hours of white blood cellwhich attracts staining white blood cells to cytoplasmic the site of granules; bilobed inflammation and nucleus widens blood vessels Monocytes (a type give rise to gray-blue 100-700 several months of agranulocytes) macrophages, cytoplasm with no which consume granules; U- bacteria, dead shaped nucleus cells, and cell parts by phagocytosis 2 of 1 Type of Formed Cell Function Description Number of Life Span Element Cells/mm^3 Lymphocytes (a attack damaged or round nucleus that 1,500-3,000 many years type of diseased cells or almost fills the cell agranulocytes) disease causing organisms; produce antibodies Platelets play role in blood fragments of a 250,000-500,000 5-10 days clotting megokaryocyte; small, purple- stained granules in cytoplasm • Red blood cells and transport of oxygen: • red blood cells (RBCs)-pick up oxygen in the lungs and ferry it to all the cells of the body • also known as erythrocytes • carry about 23%of the blood’s total carbon dioxide • most numerous cells in the blood • Red blood cells and hemoglobin: • a red blood cell is unusually flexible and thus able to squeeze through capillaries • each red blood cell is packed with hemoglobin • hemoglobin- the oxygen-binding pigment responsible for the cells’ red color • the hemoglobin molecule binds 200 times more readily to carbon monoxide, a product of the incomplete combustion of any carbon-containing fuel • when carbon monoxide binds to the oxygen-binding sites on hemoglobin, it blocks oxygen from binding to it, preventing the blood from carrying life-giving oxygen to the cells • the compound formed when hemoglobin binds with oxygen is called, logically enough, oxyhemoglobin • the structure of hemoglobin: 3 of 1 • each hemoglobin molecule consists of four polypeptide chains (globins) • each polypeptide chain contains a heme group with an iron atom that binds to oxygen • each hemoglobin molecule can carry up to four molecules of oxygen • Life Cycle of red blood cells: • the production of red blood cells is regulated by a negative feedback relationship between the oxygen-carrying capacity of the blood and the production of erythropoietin • steps: • (1) erythropoietin stimulates the red bone marrow to produce more red blood cells • (2) more red blood cells are produced • (3) increased oxygen delivery to tissues • (4) inhibits erythropoietin release • (5) decreased oxygen delivery to tissues • (6) a decreased oxygen delivery to the kidney stimulates the kidney to release erythropoietin • (7) increases erythropoietin release • the liver and spleen are the “graveyards” where worn-out red blood cells are removed form circulation • the remaining part of the heme is degraded to a yellow pigment, called bilirubin, which is excreted by the liver in bile • bile is released into the small intestine, where it assists in the digestion of fats • White blood cells and defense against disease: • White blood cells (WBCs)- perform certain mundane housekeeping duties, but they also serve as warriors in the body’s fight against disease • also known as leukocytes • represent less than 1% of whole blood 4 of 1 • are produced in the red bone marrow • white blood cells can squeeze between the cells that form the wall of the capillary, and gather at the site of the infection or injury • certain types of white blood cells may then engulf the “offender” in a process called phagocytosis • The two groups of white blood cells: • Granulocytes: • have granules in their cytoplasm • types of granulocytes: • neutrophils • the most abundant of all white blood cells • blood cell soldiers on the front lines • immediately begin to engulf microbes by phagocytosis • dead neutrophils make up pus • eosinophils • important against parasites • lessen allergies • basophils • play a role in some allergic reactions • release histamine, a chemical that attracts other white blood cells to the infection site • Agranulocytes: • lack cytoplasmic granules or have very small granules • types of agranulocytes: • monocytes • the largest of all formed elements • develop into macrophages • macrophages- phagocytic cells that engulf invading microbes, dead cells, and cellular debris 5 of 1 • lymphocytes • two types of lymphocytes: • (1) B lymphocytes • give rise to plasma cells, which, in turn, produce antibodies • antibodies- proteins that recognize specific molecules, called antigens, on the surface of invading microbes or other foreign cells
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