Exam 4 Review:  Chapter 26:  General Terms

body fluid - (1) Any natural liquid (water and dissolved solutes) found within the body or any liquid secretion of the body, e.g., blood, lymph, CSF, urine, semen, or saliva. (2) Total body water, contained principally in blood plasma and in the intracellular and interstitial compartments.

intracellular fluid - [aka cytoplasm] (1)  The water and dissolved solutes located within individual cells.  (2) The fluid compartment consisting of the cytoplasm (internal contents) of all the cells of the body.

extracellular fluid - (1)  The water and dissolved solutes located between individual cells in the body, including both tissue fluid and blood plasma.  (2) The fluid compartment consisting of the various fluids found external to all the cells of the body.  The extracellular fluid is often subdivided into the interstitial fluid and the plasma.

interstitial fluid = intercellular fluid = tissue fluid - (1)  The clear, yellowish protein-poor fluid located between cells in all tissues except blood; it may also be referred to as lymph; this fluid is the medium of exchange for respiratory gases, nutrients, wastes, and regulatory substances between the plasma and the tissue cells.    (2) The fluid compartment consisting of the tissue fluid but not the blood plasma.  [Note:  in terms of composition and physiological functions, lymph is equivalent to the interstitial fluid.]

lymph - The specific name give to the clear, yellowish protein-poor fluid located between cells in all tissues except blood after it has been collected into the vessels of the lymphatic drainage system; it may also be referred to as lymph before it is collected into those vessels; its functions include transport of absorbed lipids from the meals, the return of excess extracellular/interstitial fluid to the cardiovascular system, and a variety of immune defense functions.

blood plasma - The clear, yellowish fluid portion of blood in which red and white blood cells and platelets are suspended; it differs from serum in that it contains fibrin and other soluble clotting elements; this fluid is the medium of transport and solvent for respiratory gases, nutrients, wastes, and regulatory and immune defense molecules between the organs and tissues in different parts of the body.

intracellular compartment = cytoplasmic compartment - The hypothetical space, used in physiological models, which would contain all the fluid found within the cytoplasm of all the cells of the body.

two fluid compartment model - A simplifying mathematical description of water distribution within the body which may be used to understand certain physiological processes, such as exchange of dissolved solutes between cells and their environments, which assumes body water is separated into two locations:  (1) water inside cells, the intracellular = cytoplasmic compartment, and (2) the water outside cells, the extracellular compartment.

three fluid compartment model - A simplifying mathematical description of water distribution within the body which may be used to understand certain physiological processes, such as exchange of dissolved solutes between cells and their surroundings and the blood, which assumes body water is separated into three locations:  (1) water inside cells, the intracellular = cytoplasmic or intracellular compartment, (2) the water outside cells but not in the blood plasma, the intercellular or interstitial compartment, and (3) the water outside cells in the blood plasma, the plasma compartment.

semipermeable - The property of biological membranes which allows passage of some substances through the membrane while restricting the passage of other substances.

fluid balance - The homeostatic equilibrium maintained by the body for water (hydration status); water gain or deficit = water intake - water loss; it is regulated by the hypothalamus and ANS and influenced by a large number of hormones including antidiuretic hormone (ADH) = vasopressin, atrial natriuretic peptide (ANP), aldosterone, renin - angiotensin system, parathyroid hormone (PTH) = parathormone and calcitonin.

preformed water - Water obtained from the external environment by drinking fluids (~one third of the total water intake) and ingesting foods with a high moisuture content (~two thirds of the total water intake); typically more than 15% of the water obtained by the body.  [See also Water Biology.]

For some interesting animations about the chemistry of water, visit John Kyrk's web site.

metabolic water -Water obtained from the internal environment as a byproduct of the catabolic, oxidative breakdown of nutrients; typically less than 15% of the water obtained by the body.

vesicular transport - The processes of movement of water and dissolved solutes within or across cells while packaged in membrane-bound containers, vesicles; inward movement is termed endocytosis, outward movement is termed exocytosis, movement through the cell is termed transcytosis; the Golgi apparatus is often involved in the formation or processing of these vesicles; it is a form of bulk flow at the cellular level.

transcytosis - The process of transport of material across an epithelium, i.e., through the cytoplasm of an epithelial cell, by uptake (endocytosis) on one face (cell membrane) into a coated vesicle, which may then be sorted through the trans Golgi network and transported to the opposite face (cell membrane) in another set of vesicles (exocytosis); e.g., the movement if IgA molecules to the surface of a mucous membrane and the transport of lipoproteins through capillary endothelial cells.

diffusion - The spontaneous movement of molecules or other particles in solution, owing to their random thermal motion, to reach a uniform concentration throughout the solvent, a process requiring no addition of energy to the system.

bulk flow - The movement of water and dissolved solutes, in mass as opposed to a molecule at a time, within the body due the application of some form of pressure; e.g., the movement of vesicles inside cells or across cell membranes (endocytosis, exocytosis), the circulation of blood, lymph, and CSF, the secretions of various glands; the pressure may be applied by the continued synthesis of material or by the application of contractile forces.

edema - Any excessive accumulation of serous fluid or interstitial fluid (lymph) in tissue spaces or a body cavity; significant edema will produce obvious swelling of the involved tissues; it may be localized, due to venous or lymphatic obstruction or to increased vascular permeability (e.g., in inflammation), or it may be systemic due to heart failure or renal disease.

dehydration - Excessive loss of water from the body or from an organ or body part, as a result of illness or fluid deprivation or fluid loss from severe vomiting, diarrhea, or excessive sweating.

2. a simple diagram illustrating the three fluid compartment model of the body.

intracellular compartment = cytoplasmic compartment

interstitial = intercellular compartment (lymph) compartment plasma compartment

Explain:

1. why anabolic metabolism is not a significant source of metabolic water in comparison to the metabolic water generated at the end of the electron transport chain in the catabolism of nutrient molecules?

While a small quantity of water can be generated by anabolic reactions such as the dehydration syntheses used in the formation of proteins from amino acids, triglycerides from glycerol and fatty acids, polysaccharrides from monosaccharrides, and nucleic acids from nucleotides; the quantity of water consumed by catabolic reactions elsewhere in cells such as the hydrolysis of polymers (proteins, lipids, polysaccharrides, and nucleic acids) to obtain the monomers used in the anabolic reactions must be credited against the water formed by anabolism.  Therefore, very little, if any, net surplus water can be attributed to the metabolic water derived from anabolism.  Some authorities dispute if even this minor quantity of water can be considered a net gain.  On the other hand, a significant quantity of metabolic water is generated in the final step of nutrient molecule catabolism, where oxygen, the final electron acceptor, combines with two protons and two electrons, forming water at the end of the electron transport chain in the oxidative phosphorylation of ADP to ATP.  This process generates far more water than could ever form from anabolism. In fact, some desert animals are able to live on the preformed water from the food they eat, and the metabolic water generated in their metabolism of these food molecules, without ever ingesting any liquid water.