Body Fluids PDF

Body Fluids Body Fluids  Total amount of fluid in the human body is approximately 70% of body weight.  Body fluid has been divided into two compartments: – Intracellular fluid (ICF)  Inside the cells.  55% of total body water. – Extracellular fluid (ECF)...

Body Fluids Body Fluids  Total amount of fluid in the human body is approximately 70% of body weight.  Body fluid has been divided into two compartments: – Intracellular fluid (ICF)  Inside the cells.  55% of total body water. – Extracellular fluid (ECF)  Outside the cells.  45% of total body water.  Body Fluid Compartments ECF includes:  Interstitial fluid  Present between the cells  Approximately 80% of ECF  Plasma  Present in blood  Approximately 20% of ECF  Also includes  Lymph  Synovial fluid  Cerebrospinal fluid  Etc. ECF includes:  Transcellular fluid  It is the fluid contained in the secretions of the secretory cells and cavities of the body. Barriers separate Intracellular Fluid, interstitial fluid and plasma  Plasma membrane  Separates Intra- cellular fluid from surrounding interstitial fluid  Blood vessel wall  Separate interstitial fluid from plasma Composition of body fluids  Organic substances  Inorganic substances  Glucose  Sodium  Amino acids  Potassium  Fatty acids  Calcium  Hormones  Magnesium  Enzymes  Chloride  Phosphate  Sulphate Difference  ECF  ICF  Most abundant cation - Na+,  Most abundant cation - K+ – Muscle contraction – Resting membrane – Impulse transmission potential – Fluid and electrolyte – Action potentials balance – Maintains intracellular volume  Most abundant anion - Cl- – Regulation of pH – Regulates osmotic pressure – Forms HCl in gastric acid  Anion are proteins and phosphates (HPO42-) Na+ /K+ pumps play major role in keeping K+ high inside cells and Na+ high outside cell  Cell K+ Na + (Proteins) - Na + Cl - (Phosphates)- Cl- HCO3- Na + Cl-  Factors Affecting total body H2O It varies depending on body fat: 1. Infant 73-80% 2. Male adult: 60% 3. Female adult: 40-50% 4. Effects of obesity 5. Old age 45% 6. Climate Level of physical activity. Potassium K+ – Most abundant cation in ICF – Establish resting membrane potential in neurons and muscle fibers – Maintains normal ICF fluid volume – Helps regulate pH of body fluids when exchanged for H+ – Intracellular K+ concentration is necessary for protein biosynthesis by ribosomes. Sodium Na + – Most abundant cation in ECF – 90% of extracellular cations – Plays vital role in fluid and electrolyte balance as it accounts for half of the osmolarity (It is the number of particles (osmoles) per liter of solution (osmoles/L)) of ECF – Involved in cell membrane permeability.  Chloride Cl- – Most predominant anion in ECF – Moves easily between ECF and ICF because most plasma membranes contain Cl- leakage channels and transporters – Can help balance levels of anions in different fluids. Magnesium (Mg2+) – Mg2+ in ICF (45%) or ECF (1%) – Second most common intracellular cation. – Cofactor for certain enzymes and sodium- potassium pump. – Essential for normal neuromuscular activity and myocardial function. Specialized Fluids of the Body  Lymph  Cerebrospinal fluid  Aqueous humor  Sweat  Tears  others  Lymph  Clear and colorless fluid  96% water and 4% solids  Solids – – Proteins  2-6% of solids  albumin, globulin, fibrinogen, prothrombin, clotting factors, antibodies, enzymes – Lipids  5-15%  Chylomicrons  Lipoproteins – Carbohydrates  Glucose mainly – non-protein nitrogenous (NPN)  Urea and creatinine – Electrolytes  Sodium, calcium, potassium, chloride, bicarbonates  Functions of Lymph  Redistribution of fluid.  Removal of bacteria, toxins and other foreign bodies from tissues.  Route for intestinal fat absorption.  Transport lymphocytes. Cerebrospinal fluid (CSF)  Clear, colorless liquid formed within the cavities of brain and around spinal cord.  At any given time, there is 120-150ml CSF in the system.  CSF is completely replaced about three times a day. Functions of CSF  Hydraulic shock absorber.  Regulation of intracranial pressure.  It carries nutrients to the brain and the spinal cord.  Drainage route for waste products of brain metabolism.  Mass Balance and Homeostasis To maintain a state of homeostasis a relatively constant internal environment the body utilizes the principle of mass balance. The law of mass balance says that if the amount of a substance in the body is to remain constant, any gain must be offset by an equal loss. Total amount (or load) of substance x in the body= intake + production - excretion – metabolism. The body as a whole is electrically neutral  A few extra negative ions are found in the intracellular fluid, while their matching positive ions are located in the extracellular fluid.  As a result, the inside of cells is slightly negative relative to the extracellular fluid.