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بسم الله الرحمن الرحيم. Body Fluids . Dr.Mohammed Sharique Ahmed Quadri Assistant prof. Physiology Al Maarefa College. OBJECTIVES . By the end of this lecture you should be able to
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بسم الله الرحمن الرحيم Body Fluids • Dr.MohammedSharique Ahmed Quadri • Assistant prof. Physiology • Al Maarefa College
OBJECTIVES By the end of this lecture you should be able to • Describe of body fluid compartments as intra-cellular fluid (ICF) Extra-cellular fluid (ECF), interstitial fluid, trans-cellular fluid and total body water. • Describe the composition of each fluid compartment, in terms of volume and ions and represent them in graphic forms. • Describe daily intake and output of water and maintenance of water balance. • Define osmolarity • Define Isotonic, Hypotonic, Hypertonic • Name the causes of ECF hyper tonicity and hypo tonicity and its effects on body? • List factors influencing fluid compartments. • Physiology factor: age, sex, adipose tissue, etc. Pathological factors: Dehydration, fluid infusion.
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.
Minor ECF compartment : -Transcellular fluid -Lymph
OTHER EXTRACELLULAR COMPARTMENT • There are other TWO Minor Extracellular fluid compartments also: 1. Lymph 2. Transcellular fluid
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
Variation in water levels • 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
Barriers Separating Body-Fluid Compartments • Barrier between plasma and interstitial fluid • Blood vessel walls • Barrier between ECF and ICF • Cellular plasma membranes • Major differences between ECF and ICF • Presence of cell proteins in ICF that cannot permeate the cell membrane to leave the cells • Unequal distribution of Na+ and K+ and their attendant ions
Na+ and K+ Concentration In ECF & ICF Q. Why Na+ is more in ECF and K+ more in ICF? Ans: It is due to the Na+- K+ ATPase pump which pumps 3 Na+ outside the cell and 2 K+ inside the cell.
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 • Drinking liquids • Eating solid foods • Metabolically produced water (oxidation of carbohydrate, lipid, proteins) • Output • Insensible loss • Lungs • Nonsweating skin • Sensible loss • Sweating • Feces • Urine excretion • In order to maintain stable water balance, water input must equal water output.
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 Fluid • Conditions of water loss • 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.
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 .
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