Haemoglobin is one of the most important molecules in the animal kingdom. Its function is to carry oxygen to tissues. In lower invertebrates the blood pigment is present in the haemolymph and is not bound in cells. Later in the course of phylo genesis haemoglobin remains associated with cells which produce it and in this form it reaches the peripheral circulation. In higher organisms the haemoglobin production is thus determined by two main factors: haemoglobin synthesis in erythroid cells and the formation of these erythroid cells which depends on cell proliferation in haematopoietic organs. Human haemoglobin is made up of two chains which combine from four different polypeptide chains formed in varying ratios in different periods of the life cycle. During the life span of humans the following haemoglobins are formed: embryonic haemoglobins Gower 1 and 2, foetal haemoglobin F and two adult haemoglobins A and A . E-and IX-chains are part of the embryonic haemoglobins Gower 1 (E4) and 2 Gower 2 (1X2E2). These haemoglobins predominate in embryos during the second month of pregnancy and at the end of the first trimester they are completely re placed by foetal haemoglobin F (~Y2). Adult haemoglobin A consists of two IX and two ~-chains and is the main component of red cells in adults. A relatively small component of red cells accounting for less than 2 % of the total haemo globin, is haemoglobin A2 (1X0).

This presentation describes various aspects of the regulation of tissue oxygenation, including the roles of the circulatory system, respiratory system, and blood, the carrier of oxygen within these components of the cardiorespiratory system. The respiratory system takes oxygen from the atmosphere and transports it by diffusion from the air in the alveoli to the blood flowing through the pulmonary capillaries. The cardiovascular system then moves the oxygenated blood from the heart to the microcirculation of the various organs by convection, where oxygen is released from hemoglobin in the red blood cells and moves to the parenchymal cells of each tissue by diffusion. Oxygen that has diffused into cells is then utilized in the mitochondria to produce adenosine triphosphate (ATP), the energy currency of all cells. The mitochondria are able to produce ATP until the oxygen tension or PO2 on the cell surface falls to a critical level of about 4–5 mm Hg. Thus, in order to meet the energetic needs of cells, it is important to maintain a continuous supply of oxygen to the mitochondria at or above the critical PO2 . In order to accomplish this desired outcome, the cardiorespiratory system, including the blood, must be capable of regulation to ensure survival of all tissues under a wide range of circumstances. The purpose of this presentation is to provide basic information about the operation and regulation of the cardiovascular and respiratory systems, as well as the properties of the blood and parenchymal cells, so that a fundamental understanding of the regulation of tissue oxygenation is achieved.

Completely revised new edition of the definitive reference on disorders of hemoglobin.

Sweet Biochemistry: Remembering Structures, Cycles, and Pathways by Mnemonics, Second Edition makes biochemistry lively, interesting and memorable by connecting objects, images and stories to biochemistry concepts. Here, Dr. Asha Kumari has converted cycles and difficult pathways into very simple formula and short stories and images to help readers see things in complicated cycles and better visualize biochemistry. As biochemistry is evolving steadily, with new and impactful topics, this new edition has been fully updated to include mnemonics on timely topics in biochemistry such as DNA replication, RNA, transcription, translation, and CRISPR technology, as well as fundamentals of immunity. - Provides quick, indigenous formula, mnemonics, figures, poems and short stories to absorb key concepts in biochemistry - Presents original diagrams that are easy to recall - Features simplified tables for remembering distinguishing features - Updated to address evolving topics in basic and medical biochemistry, including DNA replication, RNA transcription and translation and immunity fundamentals