Body Fluids (301) - Dr. Rasha Zahran PDF

Body Fluids (301) by Dr. Rasha fekry zahran Assistant professor of Biochemistry Faculty of science, Damietta university. Body fluid: Bodilyfluids, or biofluids are liquids originating from inside the bodies of living people. They include fluids that ar...

Body Fluids (301) by Dr. Rasha fekry zahran Assistant professor of Biochemistry Faculty of science, Damietta university. Body fluid: Bodilyfluids, or biofluids are liquids originating from inside the bodies of living people. They include fluids that are excreted or secreted from the body as well as body water that normally is not. The dominating content of body fluids is body water. Approximately 60-65% of body water is contained within the cells (in intracellular fluid) with the other 35-40% of body water contained outside the cells (in extracellular fluid). This fluid component outside of the cells includes the fluid between the cells (interstitial fluid), lymph and blood.  Body Fluid Compartments In adults, body fluids constitute 55% of female and 60% of male total body mass  Intracellular fluid (ICF) inside cells About 2/3 of body fluid  Extracellular fluid (ECF) outside cells Interstitial fluid between cell Plasma in blood Also includes lymph, cerebrospinal fluid, synovial fluid, aqueous humor, endolymph, perilymph, and pleural, pericardial, and peritoneal fluids. Composition of body fluids Organic substances  Inorganic substances  Sodium Glucose  Potassium Amino acids  Calcium Fatty acids  Magnesium Hormones  Chloride Enzymes  Phophate  Sulphate  bicarbonate Body Fluid Compartments Copyright 2009, John Wiley & Sons, Inc.  intracellular fluid (ICF): The cytosol or intracellular fluid (ICF) or cytoplasmic matrix is the liquid found inside cells. cytosol is a complex mixture of substances dissolved in water. Although water forms the large majority of the cytosol, its structure and properties within cells is not well understood. The concentrations of ions such as sodium and potassium are different in the cytosol than in the extracellular fluid; these differences in ion levels are important in processes such as osmoregulation and cell signaling. The cytosol also contains large amounts of macromolecules. The cytosol consists mostly of water, dissolved ions, small molecules, and large water-soluble molecules (such as proteins).  Function of ICF: The cytosol has no single function: the site of multiple cell processes. Examples of these processes include signal transduction from the cell membrane to sites within the cell, such as the cell nucleus, or organelles. This compartment is also the site of many of the processes of cytokinesis. Another major function of cytosol is to transport metabolites from their site of production to where they are used. This is relatively simple for water- soluble molecules, such as amino acids, which can diffuse rapidly through the cytosol.  However, hydrophobic molecules, such as fatty acids or sterols, can be transported through the cytosol by specific binding proteins, which carry these molecules between cell membranes. Molecules taken into the cell by endocytosis or on their way to be secreted can also be transported through the cytosol. The cytosol is the site of most metabolism. Copyright 2009, John Wiley & Sons, Inc. Extracellular fluid: Extracellular fluid (ECF) or extracellular fluid volume (ECFV) usually denotes all body fluid outside of the cells. It is often secreted by cells to provide a constant environment for cellular operation. The remainder is called intracellular fluid. Human ECF is found in blood, lymph, body cavities, cavities and channels of the brain and spinal cord, and in muscle and other body tissues.  Subcompartments: Interstitial fluid – the extracellular fluid bathing most tissues, excluding the fluid within the lymph and blood vessels. Blood plasma – the yellow or gray-yellow, protein- containing fluid portion of blood in which the blood cells and platelets are normally suspended. The extracellular fluid also includes the transcellular fluid, which comprises about 2.5 percent of the ECF. Copyright 2009, John Wiley & Sons, Inc. Extracellular fluid content in humans  Function OF ECF: Extracellular fluid, in conjunction with intracellular fluid, helps: control the movement of water and electrolytes throughout the body. In order to maintain osmotic balance, the extracellular compartments of a mammal's body must be able to excrete and absorb water to and from the environment. Inorganic ions must also be exchanged between ECF and the external environment to maintain homeostasis. These exchanges occur across specialized epithelial cells and through a filtration process in the kidneys.  Extracellular fluid allows a solute balance between the outside and the inside of the cell, or to produce a gradient (which is commonly used to initiate diffusion, osmosis, facilitated diffusion, active transport, etc.). Blood flow delivers oxygen to arterioles, capillaries, and venules and clears waste products of metabolism. A second flow of fluid important to organ function is filtration of plasma across the microcirculation into the interstitial lymphatic compartment of the ECF. Copyright 2009, John Wiley & Sons, Inc.  Constituents: Main cations: Sodium (Na+ = 136–145 mEq/L) Potassium (K+ = 3.5–5.5 mEq/L) Calcium (Ca2+ = 2.2–2.6 mEq/L) Main anions: Chloride (Cl− = 99–109 mEq/L) Hydrogen Carbonate (HCO3− 22–26 mM) It is poorer in proteins, as compared to intracellular fluid.  Typical ion concentrations in mammalian cytosol and blood Concentration in cytosol Concentration in blood Ion (millimolar) (millimolar) Potassium 139 4 Sodium 12 145 Chloride 4 116 Bicarbonate 12 29 Amino acids in proteins 138 9 Magnesium 0.8 1.5 Calcium