Respiration

7 Key excerpts on "Respiration"

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  eBook - PDF

  Fundamentals of Animal Physiology

  • Eyeson, S R(Authors)
  • 2018(Publication Date)
  • Agri Horti Press

    (Publisher)

  Each type of system has its own intricate physiology. Discussion of such systems is of interest to the student of comparative, insect, or human physiology, but it can scarcely be considered by the general physiologist, who is concerned only with those attributes of life common to most types of living matter. The manner in which various organisms obtain oxygen from their environment and pass it on to their cells is the major theme of an interesting book by Krogh and this may very profitably be consulted. In our discussion, we shall be concerned only with gaseous metabolism itself, and the question as to how the gases arrive at or depart from the cells of an organism will not be looked into. This ebook is exclusively for this university only. Cannot be resold/distributed. 228 Fundamentals of Animal Physiology The word Respiration originally meant breathing and in ordinary everyday usage it still means just that. In terms like tissue Respiration and cell Respiration, the concept of Respiration was extended by animal physiologists to mean the passage of oxygen to, and of carbon dioxide away from, cells in organs and tissues. In recent years there has been a tendency among plant physiologists and botanists to stretch the term even further and to have it mean not so much the exchange of gases between organisms or cells and their environment but rather the effect of oxygen on the cell itself, that is to say oxidation, or more strictly speaking, that aspect of oxidation which involves free oxygen. All organisms and all cells give off carbon dioxide, but in many instances living processes can go on without oxygen gas being involved. Respiration which does not involve the uptake of oxygen is called “anaerobic Respiration” and life in the absence of oxygen is called “anaerobiosis.” The oxidative processes which do not involve free oxygen are often called fermentation processes. Anaerobic Respiration or fermentation may occur even in the presence of oxygen in the environment.

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  eBook - ePub

  Biological Systems in Vertebrates, Vol. 1

  Functional Morphology of the Vertebrate Respiratory Systems

  • J N Maina(Author)
  • 2019(Publication Date)
  • CRC Press

    (Publisher)

  1 Respiration—Fundamental Principles and Concepts 1  OXYGEN: A PARADOXICAL MOLECULE

  The development of eukaryotic cells from prokaryotic ones (about 2 billion years ago), the realization of sexual reproduction (about 1 billion years ago), and the accretion of independent cells into a cohesive, integrated, multicellular state about 700 million to 1 billion years ago were momentous events in the evolution and progress of animal life. These quantum events culminated in the rise of vertebrates and ultimately that of the endothermic-homeotherms, the most highly metabolically active modern taxon. Few processes in biology are as ancient and as important for life as Respiration. While animals can survive for weeks without food and days without water, they continually need molecular oxygen for energy production by oxidative phospholylation. Unlike metabolic substrates such as carbohydrates and fats that can be conserved in large quantities and utilized as needed, oxygen has to be unceasingly contracted from outside. In a person weighing 70 kg, at any one moment there is only about 1.55 L of oxygen in the body. Of the total amount, 370 cm3 is found in the alveoli, about 280 cm3 in the arterial blood, 600 cm3 in the capillary and venous blood, 60 cm3 dissolved in body tissues, and 240 cm3 bound to myoglobin. The quantity of oxygen dissolved in the tissues (about 0.8 cm−3 kg−1 ) can support life for about 6 minutes and only for a few seconds during exercise.

  Even before the discovery of oxygen by Joseph Priestley in 1771 and three years later determination of the gaseous composition of air by Antoine Lavoisier, it was well known that breathing [i.e., ventilation of the “body” (lungs) with air = pumping air in and out of the “chest” (lungs)], a mechanical process conspicuous particularly in large animals (especially birds and mammals) was essential for life. Until recently, death was loosely associated with cessation of breathing and the common method of killing was by strangulation. The familiar phrase “breath of life” bespeaks the importance of Respiration, i.e., acquisition of oxygen, for life. In an adult person, about 12,000 L of air passes through the lungs every day. Respiratory efficiency connotes the speed at which an animal uses its resources to meet the demands placed on it by the environment and the lifestyle that it pursues. Energy generation, its storage, and utilization are processes central to the metabolic performances of animals. Energy drives all biological processes from molecular to ecological levels. It is imperative for maintaining the structural and functional integrity of organisms and fortifying homeostasis against external and internal perturbations. Animals that can achieve and sustain high oxygen to carbon dioxide exchange ratios in relation to their body volumes and those that can establish stable tissue-to-fluid oxygen concentrations under various environmental conditions can attain the highest levels of aerobic metabolism. They are among the most ecologically successful organisms.

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  Dynamic Aquaria

  Building Living Ecosystems

  • Walter H. Adey, Karen Loveland(Authors)
  • 1991(Publication Date)
  • Academic Press

    (Publisher)

  Since the basics of photosynthesis were treated in Chapter 6, we will begin with the animal side of the cycle, particularly digestion, Respiration, and excretion. It is from within these processes that the essential environmental effects are expressed. Following a discussion of bacterial metabolism, we will briefly return to photosynthesis to more fully treat the synthesis of organic com-pounds. Although the specialized terminology will be kept minimal, a concise biological dictionary such as Curtis, 1985, may help. Respiration Animals come in a wide variety of sizes and complexities. They range from unicellular protozoa (now typically placed in a separate kingdom, the Protista), a fraction of a millimeter long, to elephants and whales where tons of complex tissues and multimillions of cells work together. The basic pattern, based on the cell, is the same in all cases. In the more complex animals, individual cells become highly organized parts of tissues and organs specialized in one or a few of the many functions of cells. A generalized animal cell is shown in Figure 2. The reader is re-ferred to a good modern text on biology (e.g., Keeton and Gould, 1986) for a discussion of all cell components. Here we will concentrate on the cytoplasm and the mitochrondria, since it is in these locales that the basic Respiration and glycolysis processes take place. When an animal eats a plant or another animal, a complex digestive process begins. The energy scrubbing is that of the oxidization or burn-ing of sugars. Simplistically this is C 6 H 1 2 O e + 6 θ 2 -> 6 C 0 2 + 6 H 2 0 + 670 kcal/mole of energy. One glucose plus six oxygen modules gives six carbon dioxide plus six water molecules plus energy. The cell cannot simply burn the sugars. Instead, it uses a small-scale chemical transfer process. Respiration produces adenosine triphosphate (ATP), a nitrogen-rich nucleic acid plus a sugar and attached phosphorus and oxygen.

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  Biocultural Creatures

  Toward a New Theory of the Human

  • Samantha Frost(Author)
  • 2016(Publication Date)
  • Duke University Press Books

    (Publisher)

  In other words, oxygen gains its importance not for an outstanding or premier role, not for a particularly extraordinary contribution to an otherwise humdrum process, but for its vulnerability to disruption, for its utter dependence on the organism’s interface with an oxygen-rich habitat. Whereas many of the steps in cellular Respiration direct our attention to cells, molecules, and their busy activities, oxygen demands that we also, at the same time, attend to the organism that is composed of cells, the or-ganism that breathes, the organism whose breathing has systemic effects. For if breathing fails, if the organism does not take oxygen in, then cellular Respiration halts not just in one cell, or in two or three, but in all cells, in the organism as a whole. Oxygen highlights the fact that the porous cells that compose bodies compose an organism. Which is to say that oxygen recalls us to the fact that in addition to being a living system composed of cells, an organism is an organism. But this is not yet the whole point. The itinerant nature of oxygen under-scores a further entailment of conceiving of bodies as energy-in-transition, as composites of chemical processes, as composing and decomposing. For organisms, composing themselves in the manner in which they compose, are crucially dependent on the traffic and transit of chemicals and mole-cules back and forth between their cells and their habitat. And just as en-ergy cannot be created from itself but instead can only be transferred, so a porous living organism constituted through transitions in energy cannot be self-sustaining in any sense of the term. The passage of oxygen via the porosity of cell membranes brings into focus not only that the interchange oxygen | 107 and transit of molecules in and out of cells is possible but also that it is critical for the living organism’s survival.

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  Postharvest Ripening Physiology of Crops

  • Sunil Pareek(Author)
  • 2016(Publication Date)
  • CRC Press

    (Publisher)

  In aerobic respira-tion (i.e., in the presence of adequate oxygen), glucose is oxidized (i.e., it furnishes high-energy electrons) and some of the energy in the electrons is extracted in the production of ATP as they pass through a number of enzymatically controlled steps, until they finally reduce oxygen to water (i.e., transfer the electrons, with the accompanying protons, to oxygen). In contrast to Respiration, photosynthesis reduces carbon dioxide (i.e., adds electrons to CO 2 ) and oxidizes water (i.e., removes electrons from H 2 O) to produce glucose and oxygen (C 6 H 12 O 6 and 6O 2 ). Carbohydrates (i.e., simple sugars like glucose derived from stored starch) are the main respiratory substrate for most postharvest commodi-ties. Although glucose contains 686 kcal/mol in chemical bonds, only 673 kcal/mol is available to do “work” because 13 kcal/mol is lost due to the increase in disorder of the products (i.e., an increase in entropy). However, only 281 kcal/mol of the 673 kcal/mol (42%) is captured in the 38 ATP (7.4 kcal/mol) formed because of the inefficiencies of phosphorylation. 5.2 Why Measure Respiration? Because Respiration is tightly controlled so that no more ATP is produced than is needed for metabolism, and because ATP production is tightly cou-pled to Respiration, the rate of Respiration is normally a very accurate indica-tor of the metabolic activity of the tissue. We do not measure Respiration to find only the rate of CO 2 production or O 2 consumption, but also the under-lying rate of metabolism in the tissue. The rate of metabolism is usually 142 P O S T H A R V E S T R I P E N I N G P H Y S I O L O G Y inversely related to the shelf life of the commodity. The higher the rate of Respiration, the more quickly there will be a decrease in the quality, nutri-tion, or taste of the commodity. Since we cannot easily measure changes in these parameters of shelf life, we use measurements of the rate of respira-tion as their surrogate.

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  Textbook of Plant Physiology

  • Pandey, Narendra Shankar(Authors)
  • 2021(Publication Date)
  • Daya Publishing House

    (Publisher)

  Chapter 5 : Respiration Cellular Respiration consists of a series of pathways by which carbohydrate and other molecules are oxidized for the purpose of retrieving the energy stored in photosynthesis and to obtain carbon compound used in the growth and maintenance of the cell. Higher plants are aerobic organisms, which means they require the presence of molecular oxygen for normal metabolism. They obtain both energy and carbon by oxidizing photoassimilates aco- ording to the following overall equation: From chemical reaction, plant Respiration can be expressed as the oxidation of the hexose to carbon di-oxide, with water as the product. Respiration is accompanied by the release of an amount of free energy. Respiratory Quotient (RQ) R.Q. is the ratio of the volume of the carbon dioxide released to the volume of oxygen taken in Respiration in the given period of time at standard temperature and pressure. The value of R.Q. varies with the respiratory substrates and their oxidation. R.Q. of carbohydrate, The Respiration reactions can be grouped into four major processes: 1. Glycolysis, 2. Citric acid cycle, 3. Pentose phosphate pathway, and 4. Oxidative phosphorylation This ebook is exclusively for this university only. Cannot be resold/distributed. 5.1 Glycolysis In the early steps of glycolysis (from the Greek words glykos , “sugar,” and lysis , “splitting”), carbohydrates are converted to hexose phosphates, which are then split into two triose phosphates. In a subsequent energy-conserving phase, the triose phosphates are oxidized and rearranged to yield two molecules of pyruvate, an organic acid. Besides preparing the substrate for oxidation in the citric acid cycle, glycolysis yields a small amount of chemical energy in the form of ATP and NADH. When molecular oxygen is unavailable–for example, in plant roots in fooded soils–glycolysis can be the main source of energy for cells.

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  Biology of Intertidal Animals

  • Richard C. Newell(Author)
  • 2021(Publication Date)
  • Pisces Conservation Ltd

    (Publisher)

  An enzymatic sequence involving the gradual degradation of the glucose molecule into carbon dioxide and water under aerobic conditions is therefore used; the energy is liberated in relatively small amounts which can be stored as ATP. When energy is required for a particular reaction sequence, the terminal phosphate group of the ATP molecule is transferred to a second molecule called a 'phosphate acceptor', the energy originally stored in the ATP molecule being released, leaving adenosine diphosphate (ADP). This can in turn be rephosphorylated back to ATP by the transfer of phosphate from a high energy compound called a 'phosphate donor' which has gained its energy from one of the energy-yielding steps in the degradation of the original glucose molecule. B. THE PROCESS OF Respiration Respiration commonly involves the oxidation of glucose or an equivalent 6-carbon sugar in such a way that the energy content can be liberated in a large number of steps and stored in the form of adenosine triphosphate (ATP). If a mole of glucose were completely oxidised in air, the end product would be carbon dioxide and water plus 686,000 calories of heat representing the energy contained in the molecule of glucose. We may represent this basic reaction thus: The structure of ATP is shown in Fig. 9.3 from which it is seen that the molecule is built up of a heterocyclic ring derivative of purine called adenine, RESPIRATORY MECHANISMS 510 attached to which is the 5-carbon sugar D-ribose. Attached to the D-ribose sugar are three phosphate groups, the last containing the high energy which is released when the terminal phosphate is removed by enzymatic hydrolysis. Thus ATP acts as a store of the energy which is liberated by the stepwise oxidation of Fig. 9.3. Diagram illustrating the structure of adenosine triphosphate (ATP).

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