2 Functions of Body Fluids Transports gases, nutrients, and wastesHelp to generate the electrical activity needed to power body functionsTakes part in the transforming of food into energyMaintains the overall function of the body
3 Distribution of Body Fluids Intracellular compartment (ICF)Consists of fluid contained within all of the billions of cells in the bodyLarger of the two compartments, with approximately two thirds of the body water in healthy adultsHigh concentration of K+Extracellular compartment (ECF)Contains the remaining one third of body waterContains all the fluids outside the cells, including that in the interstitial or tissue spaces and blood vesselsHigh concentration of Na+
8 Question Which ion is in the highest concentration in the ICF? Na+ K+ Cl-Ca2+
9 AnswerNa+K+: Potassium is the most abundant ion of the ICF and is responsible for the membrane potential.Cl-Ca2+
10 Diffusion and Osmosis Concentration gradient Diffusion Osmosis Difference in concentration over a distanceDiffusionThe movement of charged or uncharged particles along a concentration gradient from an area of higher concentration to one of lower concentrationOsmosisThe movement of water across a semi-permeable membrane from the side of the membrane with the lesser number of particles and greater concentration of water to the side with the greater number of particles and lesser concentration of water
11 TonicityThe osmotic pressure gradient of two solutions separated by a semipermeable membraneSolutions can be classified according to whether or not they cause cells to shrink.Isotonic: neither shrink nor swellHypotonic: swellHypertonic: shrink
12 Physiology of water balance Na+ retention causes this volume to expandNa+ loss causes this volume to decreaseWater moves freely within intracellular and extracellular compartments, keeping osmolality equal
13 Edema Edema = Accumulation of water in interstitial space Collections of fluid in body cavitiesHydrothorax – serous fluid in the thoracic cavityHydroperitoneum (ascites)Hydropericardium fluid in the pericardial sacAnasarca = severe, generalized edema with profound subcutaneous edema
14 Pathophysiology of Edema The normal flow of fluid through the interstitial space depends on four factors:Capillary hydrostatic pressure that filters fluid from the blood through the capillary wallOncotic pressure exerted by the proteins in the blood plasmaPermeability of the capillariesPresence of open lymphatic channels that collect some fluid forced out of the capillaries by the hydrostatic pressure of the blood and return the fluid to the circulation
16 Mechanism of Edema Formation Increased hydrostatic pressureReduced plasma oncotic pressureDecreased lymph outflow (lymphatic channel obstructionIncreased capillary membrane permeabilityRetention of water and salts
17 Hydrostatic pressure increases due to: Venous obstruction:thrombophlebitis (inflammation of veins)hepatic obstructiontight clothing on extremitiesprolonged standingSalt or water retentioncongestive heart failurerenal failure
19 Decreased plasma oncotic pressure: ↓ plasma albumin • liver disease • protein malnutritionplasma proteins lost in: • glomerular diseases of kidney • hemorrhage, burns, open woundsidiopathic edemaprotein leakage from capillaries
20 Nephrotic SyndromeAscites is the build up of fluid in the space between the lining of the abdomen and abdominal organs (the peritoneal cavity). Ascites results from high pressure in the blood vessels of the liver (portal hypertension) and low levels of a protein called albumin. Usually due to severe liver damage.Nephrotic syndrome is caused by different disorders that damage the kidneys. This damage leads to the release of too much protein in the urine.Cancer, diabetes, lupus, genetic disorders can all cause this syndrome.
23 Effects of Edema Swelling Pitting Increased body weight Functional impairmentPainImpairment of arteriole circulationOther complications
24 Clinical Consequences of Edema In skin edema may cause poor wound healing or poor clearance of infectionEdema in a closed space such as the calvarium can cause increased pressure, which may cause herniation of the brain
25 Acute pulmonary edemaDefinition: An increase in pulmonary extravascular water, which occurs when transudation or exudation exceeds the capacity of lymphatic drainage.Transudation - the passage of a substance through a membrane as a result of a difference in hydrostatic pressure; same as exudationExudation – oozing out; the slow escape of liquids from blood vessels through pores or breaks in the cell membranes
26 Stages of pulmonary edema Interstitial pulmonary edemaCresentic alveolar fillingAlveolar floodingAirway floodingWith gradual onset these may be identifiable clinically, however with fulminant disease progression may be obscuredThere is usually prodromal stage in which lymphatic drainage is increase, though there is no detectable increase in lung waterCrescentic – Interstitial edema increases and there is passage of fluid into the alveoli. However, the center of the alveoli and the most of the alveoli walls remain clearAlveolar Flooding - Fluid enters the alveoli in a crescentic fashion until the surface tension rises sharply and further fluid is drawn into the alveolus as the pressure gradient rises exponentially.Clearly no gas exchange can occur in flooded alveoli.Fulminante - is any event or process that occurs suddenly and quickly, and is intense and severe to the point of lethalityProdromal - An early symptom indicating the onset of an attack or a disease.
28 Stages of Cardioigenic Pulmonary Edema Elevated LA pressure causes distention and opening of small pulmonary vesselsStage 2Fluid and colloid shift into the lung interstitium from the pulmonary capillaries, but an initial increase in lymphatic outflow efficiently removes the fluid.
29 Stages of Cardioigenic Pulmonary Edema As fluid filtration continues to increase and the filling of interstitial space occurs, fluid accumulates in the relatively noncompliant interstitial space.At this stage, abnormalities in gas exchange are noticeable, vital capacity and other respiratory volumes are substantially reduced, and hypoxemia becomes more severe.
30 Toxic pulmonary edemaIncreased vascular permeability due to toxic damage ofpulmonary capillaries.
31 High Altitude Pulmonary Edema (HAPE) Hypoxic vasoconstrictionBlood vessel leakageFluid builds up in the lungsHAPE is a noncardiogenic form of pulmonary edema resulting from a leak in the alveolar capillary membrane.Autopsy studies performed on patients who died of HAPE have shown a proteinaceous exudate with hyaline membranes. Most reports mention capillary and arteriolar thrombi with deposits of fibrin, hemorrhage, and infarcts. The findings suggest a protein-rich edema with a possibility that clotting abnormalities may be partially responsible for this illness.The person usually notices fatigue, weakness, and dyspnea on exertion. The condition typically worsens at night, and tachycardia and tachypnea occur at rest. Periodic breathing during sleep is almost universal in sojourners at high altitude. Cough, frothy sputum, cyanosis, rales, and dyspnea progressing to severe respiratory distress are symptoms of the disease. A low-grade fever, respiratory alkalosis, and leukocytosis are other common features. In severe cases, an altered mental status, hypotension, and death may result.
32 Methods for Assessing Edema Daily weightVisual assessmentMeasurement of the affected partApplication of finger pressure to assess for pitting edema
33 Water and Na+ Balance Gain Water Oral intake and metabolism of nutrientsNa+LossKidneysSkinLungsGastrointestinal tractBaroreceptors regulate effective volumeModulating sympathetic nervous system outflow and ADH secretionAtrial natriuretic peptideRenin-angiotensin-aldosterone systemAngiotensin IIAldosterone
34 Regulators of Sodium The kidney is the main regulator of sodium. Monitors arterial pressure; retains sodium when arterial pressure is decreased, and eliminates it when arterial pressure is increasedThe rate is coordinated by the sympathetic nervous system and the renin-angiotensin-aldosterone system (RAAS).Atrial natriuretic peptide (ANP) may also regulate sodium excretion by the kidney.
35 Physiologic Mechanisms Assisting in Regulating Body Water ThirstPrimarily a regulator of water intakeADHA regulator of water outputBoth mechanisms respond to changes in extracellular osmolality and volume.
36 QuestionWhich ion will have the greatest effect on the membrane potential?BicarbonateK+Cl-Mg2+
37 AnswerBicarbonateK+: Slight deviations in potassium concentration will directly change the membrane potential.Cl-Mg2+
38 Disorders of ADH Expression Diabetes insipidusDeficiency of or a decreased response to ADHUnable to concentrate urine during periods of water restriction, leading to excretion of large volumes of urineNeurogenic diabetes insipidusCentral diabetes insipidusSyndrome of inappropriate antidiuretic hormone (SIAH)Failure of the negative feedback system that regulates the release and inhibition of ADH
39 Types of Diabetes Insipidus Central or neurogenic diabetes insipidusOccurs because of a defect in the synthesis or release of ADH by the HypothalamusUsually Idiopathic but may be due to autoimmune disease such as Sarcoidosis, head trauma, or tumorNephrogenic diabetes insipidusOccurs because the kidneys do not respond normally to ADH
40 Diabetes Insipidus Excessive Urination Extreme Thirst Urine does NOT contain Glucose
42 Mechanisms Protecting Extracellular Fluid Volume Alterations in hemodynamic variablesVasoconstriction and an increase in heart rateAlterations in sodium and water balanceIsotonic contraction or expansion of ECF volumeHypotonic dilution or hypertonic concentration of extracellular sodium brought about by changes in extracellular water
43 Causes of Fluid Volume Excess Inadequate sodium and water eliminationExcessive sodium intake in relation to outputExcessive fluid intake in relation to output
44 Vitamin D, Calcitonin, and Parathyroid Hormone Vitamin D acts to sustain normal plasma levels of calcium and phosphorus by increasing their absorption from the intestine.Calcitonin acts on the kidney and bone to remove calcium from the extracellular circulation.
45 Mechanisms Regulating Calcium, Phosphorus, and Magnesium Balance Calcium, phosphorus, and magnesium are the major divalent cations in the body.They are:Ingested in the dietAbsorbed from the intestineFiltered in the glomerulus of the kidneyReabsorbed in the renal tubulesEliminated in the urine
46 Physiologic Calcium ECF calcium exists in three forms Protein bound 40% of ECF calcium is bound to albumin.Complexed10% is chelated with citrate, phosphate, and sulfate.Ionized50% of ECF calcium is present in the ionized form.
47 Calcium Gain and Loss Gains Dietary dairy foods Parathyroid hormone and vitamin D stimulate calcium reabsorption in the nephron.LossesOccur when dietary intake and calcium absorption are less than intestinal secretion
48 Causes and Symptoms of Hypercalcemia Increased intestinal absorptionExcessive vitamin D and calciumMilk-alkali syndromeIncreased bone resorptionIncreased parathyroid hormoneMalignant neoplasmsProlonged immobilizationDecreased eliminationThiazide, lithium therapySymptomsChanges in neural excitabilityAlterations in smooth and cardiac muscle functionExposure of the kidneys to high concentrations of calcium
49 Causes and Symptoms of Hypocalcemia Impaired ability to mobilize calcium from bone storesAbnormal losses of calcium from the kidneyIncreased protein binding or chelation such that greater proportions of calcium are in the nonionized formSoft tissue sequestrationSymptomsIncreased neuromuscular excitabilityCardiovascular effectsNerve cells less sensitive to stimuli
50 Role of Phosphorus in the Body Plays a major role in bone formationEssential to certain metabolic processesThe formation of ATP and the enzymes needed for metabolism of glucose, fat, and proteinNecessary component of several vital parts of the cellIncorporated into the nucleic acids of DNA and RNA and the phospholipids of the cell membrane
51 Role of Phosphorus in the Body (cont.) Serves as an acid–base buffer in the extracellular fluid and in the renal excretion of hydrogen ionsNecessary for delivery of oxygen by the red blood cellsNeeded for normal function of other blood cellsWhite blood cells and platelets
52 Common Causes of Hypophosphatemia and Hyperphosphatemia Depletion of phosphorus due to insufficient intestinal absorptionTranscompartmental shiftsIncreased renal lossesHyperphosphatemiaFailure of the kidneys to excrete excess phosphateRapid redistribution of intracellular phosphate to the ECF compartmentExcessive intake of phosphorus
53 Magnesium Balance Essential to all reactions that require ATP Regulation at kidney levelMagnesium absorption in the thick ascending loop of Henle is the positive voltage gradient created in the tubular lumen by the Na+-K+-2Cl– cotransport systemIngested in the dietAbsorbed from the intestineExcreted by the kidneys
54 Manifestations of Hypomagnesemia Laboratory valuesSerum magnesium level less than l.8 mg/dLNeuromuscular manifestationsPersonality changes, athetoid or choreiform movements, nystagmus, tetany, positive Babinski Chvostek, and Trousseau signsCardiovascular manifestationsTachycardia, hypertension, cardiac dysrhythmias
55 Causes of Hypermagnesemia Excessive intakeIntravenous administration of magnesium for treatment of preeclampsiaExcessive use of oral magnesium-containing medicationsDecreased excretionKidney diseaseAcute renal failure
56 Question Alterations in ________________ may result in hypercalcemia. ADHNa+Vitamin DK+
57 Answer Alterations in ________________ may result in hypercalcemia. ADHNa+Vitamin D: When increased, vitamin D will result in higher retention of calcium.K+
58 Assessment of Body Fluid Loss History of conditions that predispose to sodium and water losses, weight loss, and observations of altered physiologic function indicative of decreased fluid volumeHeart rateBlood pressureVenous volume/fillingCapillary refill rate
59 Psychogenic Polydipsia Compulsive water drinkingPsychiatric disordersSchizophreniaDrink large amounts of water and excrete large amounts of urine.Cigarette smokingADHInterferes with water excretion by the kidneysAntipsychotic medications increase ADH levels
60 Isotonic Fluid Volume Excess Isotonic expansion of the ECF compartment with increases in both interstitial and vascular volumesIncrease in total body sodium that is accompanied by a proportionate increase in body waterCauses of decreased sodium and water eliminationRenal functionHeart failureLiver failureCorticosteroid excess
61 Potassium Distribution and Regulation Intracellular concentration of 140 to 150 mEq/LThe extracellular concentration of 3.5 to 5.0 mEq/LBody stores of potassium are related to body size and muscle mass.Normally derived from dietary sourcesPlasma potassium is regulated through two mechanisms:Renal mechanisms that conserve or eliminate potassiumA transcellular shift between the ICF and ICF compartments
62 Abnormal PotassiumHypokalemia refers to a decrease in plasma potassium levels below mEq/L.Inadequate intakeExcessive gastrointestinal, renal, and skin lossesRedistribution between the ICF and ECF compartmentsHyperkalemia refers to an increase in plasma levels of potassium in excess of 5.0 mEq/L.Decreased renal eliminationExcessively rapid administrationMovement of potassium from the ICF to ECF compartment
63 Diagnosis and Treatment of Potassium Disorders Diagnosis is based on complete history, physical examination to detect muscle weakness and signs of volume depletion, plasma potassium levels, and ECG findings.TreatmentCalcium antagonizes the potassium-induced decrease in membrane excitability.Sodium bicarbonate will cause K+ to move into the ICF.Insulin will decrease ECF K+ concentrationCurtail intake or absorption, increase renal excretion, and increase cellular uptake
64 ADH and Aquaporin-2 Channels V1 receptorsVasoconstrictionV2 receptorsControl water reabsorptionAquaporins