鹽水代謝雙語課件3.Disorder_of_water_and_electrolyte_metabolism.ppt

chapter 2 water and electrolyte disorders,questions about infusion therapy,what kind of fluid？the nature of the infusion,how much fluid？the quantity of infusion,as a solvent, drugs can be added,main contents,1. physiologic basis of water and sodium balance 2.disturbance of water and sodium metabolism 3.disturbance of patosium metabolism,section 1.,physiological basis of disorders of water and sodium metabolism,1) to maintain the osmolality and acid-base balance 2) to play an essential role in neuromuscular activity 3) to participate in metabolism and physiological activity,1) promoting metabolism (biological reaction; act as solvent for many chemicals; hydrolysis and hydration.) 2) temperature regulation;,1. body fluid,body fluid consists of water and its solutes. physiological function of water:,physiological function of electrolyte:,1 physiological basis of water and sodium balance,. (1) the volume of the body fluid and its distribution total body water (tbw) = 60% body weight extracellular fluid (ecf) 20% intracellular fluid (icf) 40% * actively secreted by epithelium (peptic juice, sweat, csf, joint capsule fluid) * exist in connective tissue, cartilage, bone,intravascular fluid (ivf, plasma) 5% interstitial-lymph fluid (isf) 15%,transcellular fluid * slow-exchange fluid*,1 physiological basis of water and sodium balance,determining factors: fat、sex、age,1 physiological basis of water and sodium balance,childrens body fluids are greatly influenced by age,chracteristics of childrens body fluids,1 physiological basis of water and sodium balance, the younger , the more body fluids； extracellular fluid ,esp interstitial fluid accounts for a large ratio ； the more vigorous metabolism , the higher exchange rate of water； poor regulation ability may lead to water and electrolyte disturbance .,年齡對(duì)體液總量及分布的影響,1 physiological basis of water and sodium balance,the impact of age on the total amount and distribution of body fluids,daily water demand of different ages,age,1 physiological basis of water and sodium balance,(2) electrolytes and their distribution in body fluid,1 physiological basis of water and sodium balance,characteristics：,4) electrical neutral rule；,3) intralcellular and extracellular ion distribution are different,5) osmotic equilibrium；,2) anions and cations are unequal in various body fluids；,1) k,na,ca,mg can pass through vascular membrane freely, but not cell membrane;,osmotic pressure is formed by the penetration effect of the solute particles . it depends on the number of solute particles(ion or molecular) , rather than the kind or size of particles.,volume increased,volumes equal,(3) osmolality of body fluid,the osmotic pressure produced by one mole of any non- electrolyte dissolved in 1l h2o is one osmolarity ( osm ),1 mol/l non- electrolyte solute 1 osm/l osmotic pressure (osm),1 mol/l electrolyte solute: 1 mol/l nacl 2 osm/l 1 mol/l cacl2 3 osm/l,total plasma osmotic pressure refers to the sum of osmotic pressure produced by the anions,cations and non-electrolyte molecules in the plasma .,normal range : 280 310 mosm/l.,plasma colloid osmotic pressure: osmotic pressure produced by the protein molecules in the plasma . characteristics: 1, the osmotic pressure is 1.5 mosm/l 2, important in maintaining fluid exchange inside and outside blood vessels as well as blood volume,plasma crystalloid osmotic pressure: osmotic pressure generated by the crystal particles(mainly electrolytes) in the plasma . characteristics: 1, accounting for most part of the total plasma osmotic pressure 2, important in maintaining fluid exchange inside and outside cells,regulation of osmotic pressure balance:,normal: ecf osmolality = icf osmolality,imbanlancebalance: hypertonic: ecfosmicfosmosmotic gradient water out cell shrink,hypotonic: ecfosmicfosm osmotic gradient water in cell swell,water water,2. movement of water and electrolyte in body fluid,_,glucose aa cl_ hco3,urea creatinine co2 o2,water,ecf,(1) movement of solute in body fulid (capillary wall) (cell membrane) ivf isf icf protein protein protein na+ k+ ca+ mg+ k+ na+ ca+ mg+,(aa:aminoacid),1 physiological basis of water and sodium balance,(2) movement of water in body fluid,1) water exchange between icf and ecf, ivf and isf the total particle number of cation and anion in icf and in ecf are similar, maintaining the osmolar balance between icf and ecf. any alteration in ion concentration between two compartment will lead to water shift to maintain the osmolar balance. if it occurs in the cell, it may causes cell swelling or shrink. in ecf, there is a difference in protein content between ivf and isf, which is important for reserving the blood volume.,1 physiological basis of water and sodium balance,intake oral ingestion of free fluid 1000-1500 ml oral ingestion of water in foods 700-1200 ml water generated from metabolism 300 ml total 2000-2500 ml excretion urine 1200-1500 ml evaporation from skin 500 ml evaporation from lung 350 ml feces 150 ml total 2000-2500 ml,2) water intake and excretion,1 physiological basis of water and sodium balance,unexchangeable,na+ pool exchangeable,(3) homeostasis of sodium,via stool & sweat via urine (90%),bone (40%) sodium intake e c f (50%) excrete (100-200mmol) (135-145mmol/l) ( who:5-6g ) i c f (10%),1 physiological basis of water and sodium balance,3. water and electrolyte balance and regulation,(1) water balance and regulation of osmolality water balance is regulated by hypothalamus, pituitary and renal tubule through thirst and antidiuretic hormone (adh). adh is produced in the supraoptic nuclei of hypothalamus, mediated by osmoreceptors in hypothalamus, which responds to changes in the osmolality of ecf other stimuli that lead to release of adh are hypovolemia, hypotension, emotional stress, pain, and certain drugs,1 physiological basis of water and sodium balance,water balance and regulation of osmolality,baroreceptors,osmoreceptors, serum osmolality blood volume （1-2%） （5-10%） thirst adh renal distal tubules water intake water excretion serum osmolality blood volume adh act on the renal distal tubules by increasing the permeability of the tubular membrane to reabsorb more water until the osmolality returns to normal,1 physiological basis of water and sodium balance,adh: antidiuretic hormone, also called arginine vasopressin(avp), plays an important role in the renal concentration and dilution to maintain the body fluid homeostasis.,adh feedback regulation machanisms: ecf osmolality osmoreceptor adh secretion+v2 receptor adenylate cyclase/campprotein kinase a system aqp2(water channel) water permeabilityreabsorption of water,aquaporins,aquaporins : a group of membrane transport protein , which constitutes water channel and is related to the water permeability .in mammals , there are 10 kinds ( aqp0 to 9) .,water channel,peter agre (1949-) “for the discovery of water channels“ 2003 nobel prize,the effective circulating blood volume (ecbv) which is crucial for tissue perfusion is dependent on the sodium balance. relative factors: rennin angitensin ii(aii). aldosterone (ads).,(2) sodium balance and volume regulation,1 physiological basis of water and sodium balance,ads: aldosterone ,secreted by the zona glomerulosa cells in the outer cortex of the adrenal glands, its main function lies in renal retention of sodium and water, increase in potassium or hydrogen secretion.,ads regulation: ecf volume renal arterial pressure,reflex stimulation of the sympathetic nervous systemrenin secretion angiotensinogen(renal substrate)angiotensin angiotensin aldosteronesodium, potassium,sodium balance and volume regulation,ecv, bp,arteriolar constriction,renal artery pressure na+ filtration sympathetic excitation h2o angintensinogen juxtaglomerular cells renin na+ angintensin i ace (lung) angintensin ii adrenal cortex reabsorption of na+ aldosteron,1 physiological basis of water and sodium balance,anp,1.powerful diuretic and natriuretic ability 2.blocking renin - angiotensin - aldosterone system 3.reduce the extent of increased adh level after dehydration or blood loss,anp: atrial natriureitc peptide or atriopeptin,a hormone synthesized by the atrium in response to acute volume expansion,(3) the role of kidney on water and electrolyte balance,the kidney plays a critical role on maintaining internal environment stabilization. to regulate by,body fluid volume electrolyte acid-base balance,filtering the blood selectively reabsorbing water, electrolytes and non-electrolytes secreting urine.,1 physiological basis of water and sodium balance,0.51% of filtrate to be excreted as final urine,renal plasma flow (rpf) = renal blood flow (1/4 co) 45% = 1200 45% = 660 ml/min,gfr = rpf 1/5 = 125 ml/min = 180l/day (original urine),9999.5% of water in original urine is reabsorbed,1 physiological basis of water and sodium balance,disturbance of water and sodium balance,section 2.,disorders of water and sodium metabolism are the most common disorders of water and electrolyte, which may lead to alteration of fluid volume and osmolality.,a. disorder of fluid volume balance (with normal serum na2+ level),a. disorder of fluid osmolality balance (with abnormal serum na2+ level),accordingly, it may roughly divide into two types:,classification：,hyponatremia,hypernatremia,hypervolemic hypernatremia （salt intoxication）,the alteration of fluid volume may mainly influence the ecf. for example, severe loss of isotonic ecf caused by acute diarrhea may led to notable decrease of ecf volume without water shift from icf to ecf as the osmolality of icf and ecf remain unchanged. however, the effect of osmolality is mainly on the icf. - lead to water shift to maintain the osmolar balance between two compartment, which may causes cell swelling or shrink.,disorders of water and sodium metabolism,a. disorder of water and sodium with normal serum sodium level -disorder of fluid volume balance 1. extracellular fluid volume deficit 2. extracellular fluid volume excess b. disorder of water and sodium with abnormal serum sodium level -disorder of osmolality balance 1. hyponatremia 2. hypernatremia,disorder of fluid volume balance (with normal serum sodium level),1. extracellular fluid volume deficit 2. extracellular fluid volume excess,1. extracellular fluid volume deficit 2. extracellular fluid volume excess,it is usually called hypovolemia. the characteristics of this type : sodium and water are lost together in the proportion same as in plasma.,disorder of fluid volume balance (with normal serum sodium level),deposit in the third space (intestinal obstruction, hydrothorax or ascites).,acute renal failure (polyuria stage) ; chronic renal disease affecting tubule (salt-losing renal disease); insufficiency of adrenal cortex.(addison disease); long term and continuous diuresis;,2) body fluid loss via kidney:,(1) etiology and pathogenesis,1) body fluid loss from outside of kidney:,via alimentary tract (severe vomiting or diarrhea, intestinal fistula,gastrointestinal drainage),large area of burn;,sympathetic excitation,blood return to cardiac bp the heart output,sodium and water raa renal reabsorption vasoconstriction,peripheral vasoconstriction,(2) effect on the body mild decrease of body fluid (500ml) ecf,heart rate,myocardial contractility,severe decrease of body fluid (1000ml) marked vasoconstriction caused by sympathetic and aii may lead to blood redistribution, decrease the blood flow to kidney, stomach, skin and muscle to ensure the blood flow to heart and brain. laboratory examination: serum na+ normal pcv (packed cell volume) urine specific gravity urine na+ 20 mmol/l (loss via kidney),(3) pathophysiologic basis of treatment should be aimed to: restore normal blood volume oral or venous supplying isotonic saline (0.9% nacl) and then hypotonic saline (0.45% nacl) treat complication (acid-base and electrolyte disturbance) treat primary diseases (bleeding, vomiting, diarrhea),1. extracellular fluid volume deficit 2. extracellular fluid volume excess,the characteristics of this type: salt and water are retained together in the proportion same as in plasma isotonic extracellular fluid volume excess,disorder of fluid volume balance (with normal serum sodium level),isotonic extracellular fluid volume excess,shift to interstitial space or cavities,in the blood vessels,hypervolemia,edema,(volume-dependent hypertension),(pleural and peritoneal cavities hydrothorax and ascites),edema refers to an excessive fluid accumulated in the interstitial space or some cavities.,(1) concept,eg: pericardium(hydropericardium) , chest (hydrothorax), abdominal cavity (ascites), cerebral ventricle (hydrocephalus) etc.,edema occuring in cavities such as pleural cavity and peritoneal cavity is also called hydrops.,(2) types of edema,edema scale： local edema anasarca,(3) etiology,the common causes include： congestive heart failure, hepatic cirrhosis, cushing syndrome or cortisol treatment, starvation or malnutrition (hypoproteinemia) iatrogenic rapid infusion of normal saline,edema refers to an excessive fluid accumulated in the interstitial space or some cavities. 1) abnormal exchange between intra- and extra-body fluid (sodium and water retention) 2) abnormal exchange between intra- and extra-vascular fluid (formation of interstitial fluid more than back flow),(4) pathogenesis,1) abnormal exchange between intra- and extra-body fluid (retention of water and sodium),under normal circumstances,the intake and excretion of water and sodium is in dynamic balance in which kidneys play an important role. normally more than 99% of water and sodium filtered by glomeruli are reabsorbed in renal tubules, only less then 1% is excreted in the form of urine.,a decreased gfr and/or an increased water and na+ reabsorption in renal tubules may influence the glomerular-tubular balance, leading to retention of water and sodium in the body.,1) abnormal exchange between intra- and extra-body fluid (retention of water and sodium),under some pathologic condition such as decrease of ecbv or primary renal insufficiency, increased reabsorption in proximal convoluted tubules increased reabsorption in distal and collecting tubules redistribution of renal blood flow,pathogenesis of water and sodium retention, decreased glomeruli filtration rate (gfr),the main causes include: a) extensive glomeruli disease acute or chronic glomerulonephritis (inflammatory exudation; markedly reduced surface area for filtration). b) remarkably decreased ecbv congestive heart failure, nephrotic syndrome. (sympathetic-adrenal medulla and r-a system excitation, leading to afferent arteriole constriction and further reduced renal blood flow), h2o and na+ excretion ,gfr ,accumulation in the body,gfr , decreased glomeruli filtration rate (gfr),a) anf(p) (decreased secretion of atrial natriuretic factor or atrial natriuretic polypeptide) b) ff (increased filtration fraction of glomeruli), increased reabsorption in proximal convoluted tubules,anf was found in the atrial tissue, which regulates blood volume and sodium concentration in plasma.,a) anf,thus a remarkable decrease of ecbv as in heart failure may increase the reabsorption of water and sodium due to a decreased secretion of anf,ecbv ,b) ff,colloid osmotic pressure ,hydrostatic pressure ,proximal tubule capillary,congestive heart failure nephrotic syndrome,in normal ff= gfr / rpf = 20%,(rpf = renal plasma flow),pr, hp,renal plasma flow,efferent arteriolar resistance,ff ,non-filtered blood concentrated,reabsorption of water and sodium,the reabsorption of water and sodium by distal and collecting tubule is regulated by hormones, mainly aldosterone and antidiuretic hormone (adh).,water and sodium reabsorption ,aldosterone and adh ,secretion and deactivation ,increased reabsorption in distal and collecting tubules,more than 90% of rbf supplies the renal cortex ( with short loops of henle, tend to excrete na+and h2o), redistribution of renal blood flow,cortical nephrons,juxtmedullary nephrons,normally,less than 10% goes to renal medulla (with long loops and stronger capability of retaining na+and h2o),under some pathologic conditions (e.g. heart failure) rbf shifts from cortical nephrons to juxtamedullary nephrons, result in an increased reabsorption of na+ and h2o. the causes may be there are plentiful sympathetic nerve and higher level of rennin in renal cortex.,2) imbalance of exchange between intra- and extra-vascular fluid, increased capillary hydrostatic pressure (chp) decreased plasma colloid osmotic pressure (pcop) increased capillary permeability obstruction of lymphatic flow,effective filtration pressure 0.15 kpa,lymphatic backflow,plasma colloid osmotic pressure 3.72 kpa interstitial colloid osmotic pressure 0.67kpa,capillary hydrostatic pressure 2.23 kpa interstitial hydrostatic pressure 0.87 kpa,push draw,exchange between intra- and extra-vascular fluid,interstitial space,3.05,3.20,capillary, increased capillary hydrostatic pressure (chp),the common cause of chp is increased venous pressure congestive heart failure, venous obstruction by thrombosis or oppression by tumor arter