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Body Fluid . Homeostasis . “Milieu Interieur ” State of constancy Dynamic Relative . Water – 45-75%. Skin, muscle and other organs ~75% Bone 25% Fat 10%. Accounts for the variation of body water % from individual to individual .
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Homeostasis “Milieu Interieur” State of constancy • Dynamic • Relative
Water – 45-75% • Skin, muscle and other organs ~75% • Bone 25% • Fat 10% Accounts for the variation of body water % from individual to individual
Larger PROPORTION of body fat result in lower PERCENTAGE of water ** The actual VOLUME of water is essentially the same in all body masses*** Variation of water proportion depends on the ration of this fixed water volume tovariable body volume
Insensible perspiration • Pure water • Passive evaporation • Entire skin surface • Continuous • Sweating • Electrolyte solution • Active secretion • Sweat gland • Activated by work
Quiz! Jimmy weights 70Kg, what is his daily turnover of water in liters?
2.1 – 2.8 liters • Daily water turnover • 3-4% of body weight in adult • 10% in babies
Negative water balance • Reduced intake • Excessive loss from gut • Excessive sweating • Excessive loss in expired air • Excessive loss in urine
IMPORTANT TO REMEMBER Total H2OICF ECFISFPlasma (% BW)60%40%20%15%5%
ICF Cell membrane ISF ECF Capillary wall Plasma Total Body Water (Antipyrine, D2O, T2O) Total ECF (inulin, sucrose, mannitol, Na2SO4) Evans’ Blue
Indicator has to be • Non-toxic • Diffuse readily, distribute evenly • Induce no changes in distribution of water between compartments • Easy to measure V = Q/c • Q – quantity of the indicator • c – concentration of indicator in plasma
Intracellular High in K+ Low in Na+ and Cl- Extracellular High in Na+ and Cl- Low in K+
Quantity • 7% of body mass • ~ 5 L • pH: 7.3-7.45, slightly basic
Blood accounts for 7-8% of total body weight in an average 70kg adult • Total volume of blood is about 5-6L • The plasma is the fluid portion of the blood: 90% water and 10% proteins: Albumin, Globulins, and Fibrinogen
Plasma protein can be separated by • Precipitation by salt • Sedimentation by centrifugation • Based on size • Electrophoretic mobility • Size and charge • Immunological characteristics
Quiz! Are proteins negatively charged or positively charged?
Quiz! • What are the role of plasma proteins?
Role of Plasma proteins • Determining distribution of fluid between plasma and ICF (colloidal pressure) • Viscosity of plasma – maintain blood pressure • Contribute to buffering power of plasma (it is negatively charged, neutralize H+)
Albumin • Most abundant protein in plasma (60% of total) • Normal values in plasma: 4.5 g/dl • Produced by the liver • Greatest contributor to the osmotic pressure • It also serve as a carrier for other substances like: hormones, drugs, fatty acids, billirubin and other ions, acting as a blood buffer
Globulins • Some produced by Liver others by Plasma cells • Normal values in plasma: 2.5 g/dl • There are three types of globulins: • Alpha globulins that transportbilirubin and steroids • Beta globulins that transport iron and copper • Gamma globulins that constitute the antibodies of the immune system
Fibrinogen • Synthesize in the Liver • Converted to Fibrin in the clotting process • Normal values in plasma: 0.3 g/dl
LYMPHOID TISSUE γ Globulin Fibrinogen α1, α2, β Globulins Albumin
ISF PLASMA capillary wall 0.9% NaCl 300 mOsm o.p. = 6.7 atms = 5100 mm Hg 0.9% NaCl 300 mOsm o.p. = 6.7 atms = 5100 mm Hg
OnlyNON-DIFFUSIBLEsolutes contribute tothe effectiveo.p.of a solution Diffusible solutes doNOTcontribute, sincethey become equally distributed on the 2 sides of the membrane PLASMA PROTEINSareNON-DIFFUSIBLE therefore, they can exert an osmotic effect This effect is known as the COLLOIDAL OSMOTIC (ONCOTIC) PRESSURE (C.O.P.) OF PLASMA = 25 mm Hg
ISF PLASMA 0.9% NaCl 300 mOsm o.p. = 6.7 atms = 5100 mm Hg 0.9% NaCl 300 mOsm o.p. = 6.7 atms = 5100 mm Hg Colloidal Osmotic Pressure (C.O.P.) or Oncotic Pressure due to plasma proteins =25 mm Hg
Transport across capillary wall • BULK FLOW – a pressure difference • Capillary hydrostatic pressure • FILTRATION – bulk flow across a porous membrane • Takes into consideration permeability of capillary • STARLING FORCES determine the distribution of ECF volume between Plasma and ISF
Factors That Can Increase Capillary Filtration • Increase Capillary Hydrostatic Pressure • Decrease capillary Colloid Osmotic Pressure
Major Factors that cause Increased Capillary Filtration of Fluid and Protein into the Interstitium • Increased capillary Hydrostatic Pressure • Decreased Plasma Colloid Osmotic Pressure
Erythrocytes • Most numerous type of blood cells • RBCs life span 120 days,broken down in the spleen • RBCs express receptors for EPO • Emerge from bone marrow as reticulocytes, it takes 24-48 hrs to become a mature RBC • 1% of the total RBCs is generated daily from bone marrow • Reticulocyte count reflects erythropoietic activity of the bone marrow
Quiz! • With no Mitochondria, how does RBC procure energy?
Quiz! • Hb occupies what percentage of RBC ? • The majority of RBC is what?
Hb: 33% of RBC • Majority of RBC is water • Rest is lipid, protein and ions
Hemoglobin • Hgb is composed of two pairs of polypeptide chains • Each of the four polypeptide consist: • Globin (protein) – alpha and beta chain • Heme unit which surrounds an atom of iron
Quiz What is solubility of O2 in plasma without Hb? That is O2 carrying capacity with Hb?
0.3ml O2/100mL • With Hb it is 20 ml O2/mL
A few values for Hb • Male 16 g/ 100ml blood • Female 14 g /100ml blood • Each gram of Hb holds 1.34 ml O2
Quiz How long does it take for stem cell to become a MATURE RBC?
3-5 days for division and differenciation • Then 24 as reticulocytes in circulation • Total of 4-6 days
Hematopoiesis • Commences in embryonic yolk sac, early red blood cells • After 6 weeks of gestation, fetal liver begins producing primitive WBCs,RBCs,andPlts • Spleen becomes a secondary site of blood cells production • Definitive long term site in the bone marrow • Active marrow sites, red bone marrow, in adult: sternum, scapula, vertebrae, pelvis, ribs, and proximal femur and humerus
Erythropoiesis • Regulated by decreased oxygen content sensed by the kidneys • Kidneys Increase production EPO, that stimulates release of large number of reticulocytes into circulation • Human EPO produced by recombinant DNA technology used for management of anemias
Hormonal effect on erythropoietin • TESTOSTERONE • Increase release of Erythropoietin • Increase sensitivity of RBC precursors to Erythropoietin • Estrogen has opposite effect
Hemoglobin-Iron cycle • Rate Hgb synthesis depends on availability of iron • 80% of body iron complexed to Heme in Hgb • 20% stored in bone marrow, liver, spleen, and other organs • Dietary Iron absorbed in the small intestine, especially duodenum • Absorbed iron enters circulation and combines with a beta globulin(apotransferrin) to form transferrin
Quiz What is the normal level of reticulocyte?
Less than 1% • Number of reticulocyte reflects theamount of effective erythropoiesis in bone marrow • Hemorrages, decrease O2 avalability, or increase O2 requirement can increase the amount of reticulocytes in the body