Notes.docx - Hemoglobin(also spelled haemoglobin and...

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Hemoglobin(also spelledhaemoglobinand abbreviated Hbor Hgb) is IIron-containing oxygen-transport metalloproteinin the red blood cellsof all vertebratesand the tissues of some invertebrates. Hemoglobin in the bloodis what transports oxygen from the lungsor gillsto the rest of the body where it releases the oxygen for cell use, and collects carbon dioxide to bring it back to the lungs.In mammals the protein makes up about 97% of the red blood cells' dry content, and around 35%of the total content (including water)[citation needed]. Hemoglobin has an oxygen binding capacity of 1.34 ml O2per gram of hemoglobin,[3]which increases the total blood oxygen capacityseventyfold.[4]Hemoglobin is involved in the transport of other gases: it carries some of the body's respiratory carbon dioxide(about 10% of the total) as carbaminohemoglobin, in which CO2is bound to the globin protein. The molecule also carries the important regulatory molecule nitric oxidebound toa globin protein thiolgroup, releasing it at the same time as oxygen.[5]Hemoglobin is also found outside red blood cells and their progenitor lines. Other cells that contain hemoglobin include the A9 dopaminergicneurons in the substantia nigra, macrophages, alveolar cells, and mesangial cellsin the kidney. In these tissues, hemoglobin has a non-oxygen-carrying function as an antioxidantand a regulator of iron metabolism.[6]Hemoglobin and hemoglobin-like molecules are also found in many invertebrates, fungi, and plants. In these organisms, hemoglobins may carry oxygen, or they may act to transport and regulate other things such as carbon dioxide, nitric oxide, hydrogen sulfide and sulfide. A variant of the molecule, called leghemoglobin, is used to scavenge oxygen, to keep it from poisoning anaerobicsystems, such as nitrogen-fixing nodules of leguminousplants.
Bloodis a specialized bodily fluidthat delivers necessary substances to the body's cells– such asnutrients and oxygen– and transports wasteproducts away from those same cells.In vertebrates, it is composed of blood cellssuspended in a liquidcalled blood plasma. Plasma, which constitutes 55% of blood fluid, is mostly water (92% by volume),[1]and contains dissolvedproteins, glucose, mineral ions, hormones, carbon dioxide(plasma being the main medium for excretory product transportation), plateletsand blood cells themselves. The blood cells present inblood are mainly red blood cells(also called RBCs or erythrocytes) and white blood cells, including leukocytes and platelets. The most abundant cells in vertebrate blood are red blood cells

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