Body Fluids Lecture Notes PDF

‫بسم الله الرحمن الرحيم‬ Body Fluids Dr Nisreen Daffa Alla Omer M.B.B.S, Ph. D (Human Physiology), MSc medical education Assistant prof. Physiology Al Maarefa University& University of Khartoum...

‫بسم الله الرحمن الرحيم‬ Body Fluids Dr Nisreen Daffa Alla Omer M.B.B.S, Ph. D (Human Physiology), MSc medical education Assistant prof. Physiology Al Maarefa University& University of Khartoum 1  OBJECTIVES By the end of this lecture you should be able to: Describe of body fluid compartments Describe the composition of each fluid compartment List factors influencing fluid compartments Describe daily intake and output of water and maintenance of water balance. Define osmolarity Define Isotonic, Hypotonic, Hypertonic &List some clinical causes of each. 2  Total Body Water: 60% of body weight ( less in females ) Total body water : approx. 42 lit in 70 Kg body wt Intracellular Fluid (Within body cells): 2/3 of TBW (40%of body wt.) 28 L in 70kg body wt. Extracellular Fluid (Out side body cells) : 1/3 of TBW(20% of body wt.) 14L in 70 kg body wt. 3  Minor ECF compartment : -Transcellular fluid -Lymph 4  Minor ECF Compartment (cont) 1. Lymph : fluid returned from the interstitial fluid to plasma by Lymphatic System. 2. Transcellular Fluid It is small fluid volume secreted by specific cells in the body. Example : Cerebrospinal fluid (CSF)- it surrounds the Brain and Spinal cord Intra ocular fluid - in the eye Synovial fluid – lubricating joints Pericardial fluid, Intra pleural fluid 5  Barriers Separating Body- Fluid Compartments Barrier between plasma and interstitial fluid – Blood vessel walls Barrier between ECF and ICF – Cellular plasma membranes 6 Classification of Body Fluids Factors affects total body water 8  Variation in water levels Lean tissue Vs adipose tissue; lean tissue have higher fluid content than fat tissue Gender: males have more lean tissue hence more body fluids Age: Lean tissue lost with the age hence body fluid decreases with age Lean tissue : Muscle tissue without fat 9 Differences between ECF and ICF in a 70 Kg adult male difference ECF ICF VOLUME 15L 25L Na+ 142mmol/L 10mmol/L K+ 4mmol/L 140mmol/L Ca++ 2.5mmol/L negligible Cl- 105mmol/L 4mmol/L HCO3- 25mmol/L 10mmol/L Protein- 17mEq/L 65mEq/L pH 7.4 7.2 Osmolarity 280 – 280 – 300mOsmol/ 300mOsmol/L L Ionic Composition of the Major Body- Fluid Compartments  Important Differences Between ECF & ICF INTRACELLULAR FLUID [ICF] EXTRACELLULAR FLUID [ECF] 1. ICF has more protein 1. No protein in Interstitial Fluid. Protein present in Plasma. 2. More Potassium ion 2. Less Potassium ion (145 mmol / l) (4 mmol / l) 3. Less Sodium ion 3. More Sodium ion (10 mmol / l) (145 mmol / l) 4. More Phosphate ion 4. More Chloride ion 12 Proteins present in plasma & ICF only 13  Fluid Balance Two factors are regulated to maintain fluid balance in the body – ECF volume must be closely regulated to help maintain blood pressure Maintaining salt balance is very important in long-term regulation of ECF volume – ECF osmolarity must be closely regulated to prevent swelling or shrinking of cells Maintaining water balance is very important in regulating ECF osmolarity  H2O Input and Output Input Output Drinking – Insensible loss liquids Lungs Nonsweating Eating solid skin foods – Sensible loss Metabolically Sweating produced water Feces (oxidation of Urine carbohydrate, lipid, Inproteins) excretion order to maintain stable water balance, water input must equal water output. 15 Daily Water Balance 16  ECF OSMOLARITY  What is Osmolarity ? Osmolarity is the concentration of solute particles dissolved in the fluid. Increased Osmolarity means higher concentration of solute and less concentration of water.  ECF Osmolarity (cont) As Na+ is the main solute in ECF, it is responsible for ECF Osmolarity. In ICF K+ is responsible for ICF Osmolarity. Normally ECF and ICF are ISOTONIC (having same Osmolarity).  Extracellular Fluid Osmolarity Normally Osmolarity of ECF and ICF are the same (they are isotonic).  Why ? Because total concentration of Na+ and other solutes in ECF is equal to total concentration of K+ and other solutes inside the cell.  Remember Osmolarity of ECF-285 mmol/l (275-295)  Importance of regulating ECF Osmolarity  PROBLEM  If there is water loss from the ECF , what will be its effect? Answer – ECF will become Hypertonic.  Hypertonic Extracellular Conditions of water loss – Fluid Diarrhea – Vomiting – Sweating – Less water intake. If ECF becomes hypertonic, water moves from inside to outside of cell by osmosis (i.e. from ICF to ECF). As water leaves the cell – cell shrinks.  Clinical Application In mild Dehydration (loss of water) and mild hyper tonicity : – There is dry skin – Dry tongue &thirst – Sunken eyes. In case of severe Hyper tonicity ( Hyper Osmolarity) of ECF, it may affect BRAIN CELLS and BRAIN FUNCTION --- person may become mentally confused. Signs of dehydration  HYPOTONIC ECF  PROBLEM  What will happen if ECF becomes Hypotonic (that is having less Osmolarity) ? Answer – When ECF becomes Hypotonic , water will enter the cell, and cell will swell ( Get bigger).  NOTE – Usually Hypo tonicity does not occur because when we take more water, we loose water in urine, but it can happen in Abnormal conditions.  Hypotonic Extracellular Fluid(cont) Clinical Application Renal failure: Patient can not pass urine , ECF will become hypotonic. When ECF becomes hypotonic, water enters into the cell by Osmosis and cells swells (increase in size). Swelling of BRAIN cells will cause Brain Dysfunction E.g. – headache, vomiting, confusion, drowsiness and coma. This is called WATER INTOXICATION.  ISOTONIC SOLUTIONS  What will happen if we give Isotonic solution? Answer – If we give ISOTONIC SOLUTION like 0.9% saline (Isotonic saline) intravenously, ECF will remain ISOTONIC , there will be no net movement of water into or out of the cells. Only ECF volume will increase.  NOTE – In case of Diarrhea, vomiting , Isotonic saline is given intravenously.  Classroom questions What is the largest & smallest body fluid compartments What is the membrane that separate the ICF from ISF Why water is less in elderly, obese and females compared to young, thin and male respectively What are the major anions & cations in ICF & ECF Give one clinical cause of hypotonic & hypertonic ECF and the signs of each What is the major source of water gain & loss  References Human physiology by Lauralee Sherwood, seventh edition Text book physiology by Guyton &Hall,11th edition Text book of physiology by Linda.s contanzo,third edition