This chapter describes water as the principal constituent of the human body and is essential for life. In healthy individuals, the volume and osmolality of the tissue fluids are maintained within closely defined limits. This process is mainly concerned with the mechanisms that regulate the quantity of water that is present in the body and maintain its distribution between the different body compartments. The chapter cites some common disorders of electrolyte balance and the detailed mechanisms by which the osmolality of the body fluids is regulated. Broadly speaking, body water is distributed between the intracellular fluid or ICF and the extracellular fluid or ECF.
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Chapter
Fluid and electrolyte balance
Chapter
The hydrosphere
This chapter introduces the hydrosphere, emphasizing the critical importance of water and its unique properties. It discusses the distribution of water throughout the Earth, the physical and chemical properties of water, and the methods of expressing concentration of solutes in water. It highlights that water is one of the essentials that support all forms of plant and animal life, noting that the quality of the environment is defined by the quality of water. The chapter points out that unsafe drinking water, turbid lakes and rivers, or ponds green with algae are obvious signs of a degraded water environment. Water covers 73% of the Earth's surface, almost three times as much as the continents, but it is also a crucial component of the atmosphere and the terrestrial environment.
Chapter
Living in Water
This chapter looks at vertebrates which live successfully in water. A vertebrate must adjust its buoyancy to remain at a specific depth and must force its way through a dense medium to pursue prey or escape predators. Thus, aquatic vertebrates have evolved solutions to the physical challenges of life in water. The chapter primarily focuses on fishes and lissamphibians to consider sensory systems in water and on land. The evolutionary diversification of teleosts resulted in an enormous array of sizes and ways of life in freshwater and marine environments. The chapter details the process of osmoregulation in different environments.
Chapter
The Oceanic Environment
This chapter explores the oceanic environment. It explains the topography and structure of the ocean floor, and argues that its main features include the continental shelf, continental slope, deep-sea floor, and oceanic ridge systems. Many of the ocean's major features are due to the unique set of chemical and physical properties of water. The chapter also notes that seawater density is controlled mainly by salinity and temperature. It cites that the Coriolis effect increases with increasing latitude while it deflects currents to the right of the wind in the Northern Hemisphere and the left of the wind in the Southern Hemisphere.
Chapter
Building Blocks
Molecules and Macromolecules
This chapter discusses the building blocks of molecules and macromolecules. It cites the importance of understanding chemical compounds and chemical reactions in biology. Key properties of molecules, including their size, shape and reactions, are determined by the atoms that make them up and the ways these are bonded together into functional groups. The chapter examines the structure and function of biological macromolecules, referencing the four main classes: carbohydrates, lipids, nucleic acids, and proteins. It also discusses the function and structure of water, which holds a key role in supporting life.
Chapter
Building Blocks
Molecules and Macromolecules
This chapter discusses the building blocks of molecules and macromolecules. It cites the importance of understanding chemical compounds and chemical reactions in biology. Key properties of molecules, including their size, shape and reactions, are determined by the atoms that make them up and the ways these are bonded together into functional groups. The chapter examines the structure and function of biological macromolecules, referencing the four main classes: carbohydrates, lipids, nucleic acids, and proteins. It also discusses the function and structure of water, which holds a key role in supporting life.
Chapter
Introduction: why biologists need chemistry
This introductory chapter provides an overview of why biologists need chemistry. Chemistry explores life at the level of atoms and molecules; it is really all about understanding how atoms interact to form larger, more complicated substances, how these substances react with each other to form new substances, and how these substances behave. Biology then looks at how these substances behave when they are combined on a larger scale—the scale of cells, tissues, organisms, populations, or ecosystems. An understanding of life on a chemical scale provides invaluable insights that help in building a richer understanding of life at the larger scale of biology. Nothing captures this notion better than water, which has some unusual physical and chemical properties. This chapter examines water as an example of how chemical interactions can shape the biological world. The chapter then looks at the essential concepts that unify chemistry and biology, before considering the language of chemistry and quantitative reasoning.
Chapter
Mammals of Deserts and Dry Savannas
Water, Salts, and Excretion AT WORK
This chapter covers the interplay of water, salts, and excretion of desert mammals in dry savannas. It details how oryxes and other species of medium-sized and large mammals can live in hot deserts or dry-savanna ecosystems. In dry savanna, water is a dominant controlling factor for biological processes. Thus, the large body size of some animals plays a physiological advantage in terms of water cost. The chapter then considers the dramatic adaptation of particular species, such as wildebeests adapting to walk on long treks to find water to reduce and water expenditure to void metabolic heat and the water-conserving mechanisms of oryxes.
Chapter
Transport of Solutes and Water
This chapter focuses on the transport of solutes and water. It defines transport as any and all movements of solutes or water across cell membranes or epithelia regardless of its mechanisms. Passive-transport mechanisms, by definition, are capable of carrying material only in the direction of equilibrium. Meanwhile, active-transport mechanisms, by contrast, can carry material in the direction opposing equilibrium. The chapter also elaborates on the concept of simple diffusion and facilitated diffusion. It also discusses the diversity and modulation of channels and transporters. It also looks at the process of osmosis, which is the passive transport of water across a membrane.
Chapter
Living on Land
This chapter focuses on the demands of terrestrial life. It highlights how the viscosity of water compared to forces in the air and on land resulted in change. Since the most important difference between living in water and on land is the effect of gravity on support and locomotion, the skeletons of terrestrial tetrapods needed to be able to support the body. The chapter discusses the changes to body structures and key organ systems associated with living on land, which include feeding mechanisms, blood circulation, and sensing the world. It also details the sensory systems of terrestrial vertebrates, which looks at how terrestrial vertebrates couple olfaction and respiration.
Chapter
Life in a Fluid Medium
This chapter considers the important properties of water which strongly affect the functioning of marine organisms. Seawater is a fluid that surrounds marine organisms so its motion can be stressful and displace an organism. The very density and other physical properties of water have profound effects on marine organisms, depending on their size and shape and the water velocity conditions. The chapter considers using water motion for biological advantage, which references how the principle of continuity allows the calculation of flow velocity in a biological circulatory system. It also considers the concepts of Reynolds number, turbulence, drag, and Bernoulli's principle.
Chapter
Hydrogen
This chapter evaluates hydrogen, which is by far the most abundant element in the universe and all the other chemical elements are made from it. Without hydrogen there would be no water to drink, and DNA molecules would not form the double-helix structure that allows our genetic code to be copied and passed on to future generations. Hydrogen can form a positive ion like the metals of Group 1 but, since it is one electron short of a noble gas configuration, it can also form a negative ion and a single covalent bond, like the halogens of Group 17. Hydrogen forms compounds with many other elements but the properties of these hydrides vary considerably. The chapter then considers the self-ionization behaviour of water, which may be regarded as an acid—base reaction. It also looks at sulphuric acid and nitric acid.
Chapter
Water, Electrolytes, and Acid–base Balance
Lewis J. James and Gethin H. Evans
This chapter looks at water, electrolytes, and the acid–base balance. From a biological perspective, water is the most abundant compound in the human body and is the nutrient both consumed and lost in the largest amount each day. Despite its abundance in the body, water stores are regulated within a narrow physiological range, and even small deviations from normal body water stores exerts strong physiological, subjective, and behavioural responses that lead to the correction of the imbalance. The chapter then looks at the significance and functions of sodium and potassium, before discussing acid–base balance. Small changes in plasma pH, also called acid–base disturbances, can have significant consequences, as many enzymes and processes require a certain optimum pH in which they can operate.
Chapter
Water: Using our Planet to Quench our Thirst
This chapter looks into the sustainability of water as a resource. Water is considered a renewable resource, but rates of depletion often exceed rates of renewal. Tis is due to overexploitation and contamination. Access to water is becoming limited as a result of overdepletion, pollution, and other forces. Thus, human activity has threatened aquatic ecosystems and the services they perform. The chapter then examines how by 2050, national, international, and global policies, innovation and technology, and ecological approaches can serve as solutions to the global water crisis. It also looks at issues related to clean water, sanitation, and hygiene (WASH) following problems with public health in developing countries.
Book
Lincoln Taiz, Ian Max Møller, Angus Murphy, and Wendy A. Peer
Fundamentals of Plant Physiology is a distillation of the most important principles and empirical findings of plant physiology. First, the book covers plant and cell architecture. Then, it focuses on water and plant cells, water balance of plants, mineral nutrition, assimilation of inorganic nutrients, and solute transport. The text also looks at photosynthesis, translocation in the phloem, respiration and lipid metabolism, signals and signal transduction, signals from sunlight, and embryogenesis. Towards the end of the book, there are chapters that cover seed democracy, germination, seedling establishment, vegetative growth and senescence, flowering, fruit, biotic interactions, and abiotic stress.
Chapter
The aquatic environment
This chapter discusses the aquatic environment. Water is the most important liquid on the Earth and has a major impact on the chemical, physical, and biological processes which take place. There are many ways by which natural waters can be classified and it must be recognized that the movement of water through the environment does not limit it to any single category. It is often convenient however to consider the Earth's surface as a suitable cut-off point. Groundwater is the water below the Earth's surface. Meanwhile, surface waters can be divided into two broad categories: freshwater and seawater. The chapter then looks at the hydrologic cycle, before considering the dissolved inorganic compounds and organic material in natural waters.
Chapter
Water and Plant Cells
This chapter discusses how water plays a crucial role in the life of the plant. Photosynthesis requires that plants draw carbon dioxide from the atmosphere, and at the same time exposes them to water loss and the threat of dehydration. To prevent leaf desiccation, water must be absorbed by the roots and transported through the plant body. Even slight imbalances between the uptake and transport of water and the loss of water to the atmosphere can cause water deficits and severe malfunctioning of many cellular processes. The chapter then considers how water moves into and out of plant cells, emphasizing the molecular properties of water and the physical forces that influence water movement at the cell level. It looks at how cell walls allow plant cells to build up large internal hydrostatic pressures, called turgor pressure, and differentiates between diffusion and osmosis.
Book
Lincoln Taiz, Ian Max Møller, Angus Murphy, and Eduardo Zeiger
Plant Physiology and Development firstly introduces the topic by looking at plant and cell architecture and genome structure and gene expression. The second group of chapters in this book contains detail about the transport and translocation of water and solutes. The third section covers biochemistry and metabolism with chapters about photosynthesis, the respiration system and lipid metabolism, and stomatal biology. The book then looks at growth and development and includes chapters on cell walls, signals, embryogenesis, pollination, plant senescence, cell death, and abiotic stress.
Book
Richard Niesenbaum
Sustainable Solutions: Problems for Solving Future Generations offers a problem-solving and solutions-based approach to teaching sustainability. The first part presents an introduction to sustainability and an outline of the problems we need to solve. The next part is about the earth as a resource and focuses particularly on air, water, food, natural resources, fossil fuels, and waste. The third part of the book is about integrating sustainable solutions at different levels of organization. It looks at what we can do as individuals, the part education can play, and how communities and regions can act. The last chapter looks at the future of sustainability.
Chapter
Control of sodium, water and calcium balance
This chapter explores the control of sodium, water, and calcium balance in animals. The renin–angiotensin system is the main regulator of aldosterone secretion; aldosterone is the main salt-conserving hormone of tetrapods. Aldosterone stimulates salt absorption from the distal nephron and fluids in various non-renal tissues: amphibian urinary bladder, coprodeum and colon of birds, and sweat glands of mammals. Regulation of salt secretion by the salt glands of marine birds and reptiles is mainly via the actions of neuropeptides released from nerve fibre endings that innervate the secretory epithelia and blood vessels of the glands. The chapter then looks at diuretic and antidiuretic hormones, as well as hypercalcaemic and hypocalcaemic hormones.
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