泌尿系统教学课件：Chapt 3 Water balance and regulation of osmolality.ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,Water balance and regulation of osmolality,How will we learn in this chapter?,Causes and assessment of polyuria,Renal mechanism for urine concentration and dilution,Feedback control of plasma osmolality,Faliure to concentrate/dilute urine,Disorder of water and sodium balance,Part I:Causes and assessment of polyuria,polyuria,（,2000ml/d,）,Solute excretion increase(Osmotic diuresis),Water excretion increase,I Solute excretion increase(Osmotic diuresis),=,Solute Diuresis,large amounts of a poorly reabsorbed solute such as glucose or urea,I Solute excretion increase(Osmotic diuresis),Filtration of poorly reabsorbed solute,Reabsorption of solute,Osmotic Diuresis,Poorly reabsorbed,Osmolyte,H,2,0,H,2,0,H,2,0,Na,Na,Na,H,2,0,H,2,0,H,2,0,Na,Na,Na,Hypotonic,Saline,Osmolyte=glucose,urea,Causes of Osmotic diuresis,Infusion of manitol,Diabetes mellitus,Plasma glucose filtration,reabsorption,Chronic kidney disease(,azotemia),Diuretic drugs,II Dilute polyuria(water excretion,),Overdrinking,（,psychiatric disturbance)+kidney dysfunction,Psychogenic polydipsia,Central or nephrogenic DI,Summary:Diagnostic approach of polyuria,Part II:Renal mechanism for urine concentration or dilution,Importance:keep the normal osmolatily of plasma(290mosm/liter),When there is excess water in the body and body fluid osmolarity is reduced,the kidney can excrete urine with an osmolarity as low as 50 mosm/liter,a concentration that is only about one sixth the osmolarity of normal extracellular fluid.,Conversely,when there is a deficient of water and extracellular fluids osmolarity is high,the kidney can excrete urine with a concentration of about 1200 to 1400 mOsm/liter,The basic requirements for forming a concentrated or diluted urine,(1)a high osmolarity of the renal medullary interstitial fluid,which provides the osmotic gradient necessary for water reabsorption-(loop of Henle),(2)the controlled secretion of antidiuretic hormone(ADH),which regulates the permeability of the distal tubules and collecting ducts to water;,I,The Counter-Current Mechanism Produces a Hyperosmotic Renal Medullary Interstitium,Key substance I:sodium chloride,Figure 26.13c,Key substance II:urea,The vasa recta trap,salt and urea,within the interstitial fluid but transport,water,out of the renal medulla,Vasa recta remove more solute than water,Increased osmolarity,ADH,Post.Pituitary,Urge to drink,STIMULUS,cAMP,+,II Action of ADH in collecting ducts,The Role of ADH,There is a high osmolarity of the renal medullary interstitial fluid,which provides the osmotic gradient necessary for water reabsorption to occur,.,Whether the water actually leaves the collecting duct(by osmosis)is determined by the hormone ADH(anti-diuretic hormone),Osmoreceptors in the hypothalamus detect the low levels of water(high osmolarity),so the hypothalamus sends an impulse to the pituitary gland which releases ADH into the blood stream.,ADH makes the wall of the collecting duct more permeable to water.,Therefore,when ADH is present more water is reabsorbed and less is excreted.,Figure 26.15a,b,The Effects of ADH on the distal collecting duct and Collecting Ducts,Summary:Conditions required for urinary concentration and dilution,To concentrate the urine,Adequate soulte delivery to the loop of Henle,Normal function of the loop of Henle,ADH,To dilute the urine,Adequate soulte delivery to the loop of Henle and early distal tubule,Normal function of the loop of Henle and early distal tubule,No ADH,Hyperosmotic Renal Medullary Interstitium,Part III:Feedback control of plasma osmolity,ADH has half-life of 10-15 minutes.It is metabolized in liver and kidney.Effects of ADH on collecting tubule are rapid on and rapid off.,Releationship between the plasma osmolality and the concentration of ADH,Decrease in Blood Volume,Decrease in Blood Pressure,Stress,pain,nausea,Other factors that controll ADH secretion,Mechanism of ADH action in the kidney,Receptor of ADH:V1A,V1b,V2(kidney),AQP-2,Other actions of ADH,Intensification of the medullary interstitial concentration:,increase the activity of the sodium chloride reabsorption in thick ascending limb of the loop of the Henle,increase the permeability of the inner medullary duct to urea,Vasoconstriction(V1 receptor):,Part IV:Failure to concentrate the urine,Failure to generate the medullary concentration gradient:,poor solute delivery to the loop of Henle,impaired action of thick ascending limp of loop,Failure to ADH effect,No ADH release,No ADH action in kidney,Part V:Failure to dilute the urine,Renal failure,ADH secretion increase,Part VI:Disorders of Water and Sodium balance,I Classification,According to the changes of Na,+,e:,(1)Hypernatremia,(2)Hyponatremia,According to the changes of volume:,(1)Dehydration(Hypovolemia),(2)Overhydration(Hypervolemia),According to the changes of both Na,+,e and volume at the same time:,(1)Hypernatremia,1)Hypovolemic hypernatremia,Hypertonic dehydration(water deficit more than sodium deficit;water deficit),2)Hypervolemic hypernatremia,3)Normovolemic hyperhatremia,(2)Hyponatremia,1)Hypovolemic hyponatremia,Hypotonic dehydration,2)Hypervolemia hyponatremia,Hypotonic overhydration(water intoxication),3)Normovolemic hyponatremia,(3)Normal serum Na,+,1)Isotonic dehydration,2)Isotonic overhydration(edema),According to the clinic importance:,Dehydration,1.Hypertonic dehydration(hypovelemic hypernatremia),2.Hypotonic dehydration(hypovelemic hyponatremia),3.Isotonic dehydration,Overhydration,4.Hypotonic overhydration,Water intoxication(hypervolemic hyponatremia),5.Isotonic overhydration,Edema,I Dehydration,-,Dehydration Na,+,Osmotic pressure,(mmol/L)(mOsm/L),-,Hypertonic 150 310,Hypotonic 130 310 mOsm/L.,(2)Etiology(water decrease),1),Decreased water intake:,no water during navigation or in desert,difficulty in swallowing because of esophageal diseases,no sense of thirst due to brain injury or coma,severe vomiting,.underdose of infusion in treatment of patients,gains(ml/day)loss(ml/day),-,drink 1200 lung 300,food 1000 skin 500,metabolic feces 200,water 300 urine 1500,-,total 2500 2500,At the same time,pure water loss from lung(300ml/d)and skin(500ml/d)is not avoidable,even increased.,2)Increased loss of water,via skin,via respiration,via gastrointestinal,tract,via kidney,if water replenish is not enough.,gains(ml/day)loss(ml/day),-,drink 1200 lung 300,food 1000 skin 500,metabolic feces 200,water 300 urine 1500,-,total 2500 2500,via skin:,Normally 500 ml of pure water will be lost by insensible evaporation from skin each day.,When the environmental or body temperature is increased,the evaporation(insensible loss)will increase from skin.,Since sweat is hypotonic(0.2%NaCI),there will be more water loss than salt loss during sweating.,Elevation of 1(celsius)will increase loss of 500 ml pure water by evaporation each day.,gains(ml/day)loss(ml/day),-,drink 1200 lung 300,food 1000 skin 500,metabolic feces 200,water 300 urine 1500,-,total 2500 2500,via respiration:,Since the expired air contains water vapour,the water loss from lung is 300 ml of pure water each day.,The pure water loss is increased to 1300ml/day.during hyperventilation.,(metabolic acidosis,bronchitis,fever),gains(ml/day)loss(ml/day),-,drink 1200 lung 300,food 1000 skin 500,metabolic feces 200,water 300 urine 1500,-,total 2500 2500,via gastrointestinal tract,Vomiting and diarrhea will lose a lot of body fluid.,Gastric juice is isotonic,loss of gastric juice with the loss of pure water from skin and lung may lead to hypertonic dehydration.,The Na,+,of,watery stool is about 60 mmol/L(hypotonic fluid).,gains(ml/day)loss(ml/day),-,drink 1200 lung 300,food 1000 skin 500,metabolic feces 200,water 300 urine 1500,-,total 2500 2500,via kidney:,When the ADH secretion is reduced,such as diabetes insipidus.Increased water loss occurs.,Patients with diabetes also have increased urinary water loss due to the,osmotic diuresis.,Tube feeding with a high concentration of protein is used to unconscious(coma)patients.,The urea will increase in the urine,which causes,osmotic diuresis.,gains(ml/day)loss(ml/day),-,drink 1200 lung 300,food 1000 skin 500,metabolic feces 200,water 300 urine 1500,-,total 2500 2500,(3)Alterations of metabolism and function,1)Adaptive(compensatory)responses of the body,2)Characteristic effects of hypertonic dehydration on the body,1)Adaptive(compensatory)responses of the body,Drink more water because of severe,thirst,Hyperosmolarity and hypovolemia stimulate the sense of thirst via central osmoreceptors.,Diminished saliva and the dry mucous membranes lead to the sense of thirst.,no thirst,increase of ECF osmolality(12%),hypovolemia,elevated angiotensin II vasoconcentration,dryness of,mouth,osmoreceptor(anterior hypothalamus,),volume receptor,in venae cavae and atrium,thirst center(anterior hypothalamus),sense of thirst and drink of water,decrease of ECF osmolality,increase of ECF volume,decrease of angiotensin concentration II,disappear of dryness of mouth,Obvious thirst occurs at early stage of hypertonic dehydration.,If possible,the patient may drink water until the patient has again normal osmolarity and normal volume of ECF.,Normal,Plasma,Interstitial fluid,Intracellular fluid,Increased water reabsorption by increased ADH,ADH release is stimulated by the hyperosmolarity of the ECF and the hypovolemia.,increase of ECF osmolality(12%)via osmoreceptor,hypovolemia via volume receptor,synthesis and release of ADH,decrease osmolality of ECF,increase volume of ECF,increases the reabsorption of water in kidneys,ADH increases the reabsorption of water in kidneys.The volume of ECF will increase.The high osmolarity will decrease to normal.,2)Characteristic effects of hypovolemic hypernatremia(hypertonic dehydration)on the body,Thirst,occurs at the early stage of hypertonic dehydration.,Oliguria(except for,diabetes insipidus,),at the early stage of hypertonic dehydration.(600mOsm/L ,urine specific gravity1.020,Moderate,46%,severe thirst,，,Postural hypotension,urine osmotic pressure800mOsm/L,urine specific gravity1.025,apathy,fever,acidosis,Severe,6%,Shock,oliguria or anuria,BP decrease,hyperkalemia,serious acidosis,death,2.Hypotonic Dehydration(hypovolemic hyponatremia),(1)Concept,There is loss of both water and sodium(hypovolemia),the salt loss is in excess of water loss(hyponatremia),.,The ECF is hypotonic(Na,+,130 mmol/L),the osmolarity is lower than 280mOsm/L.,(2)Causes,1)Inappropriate treatment:,Replace of water only to the patients with dehydration caused by vomiting,diarrhea,gastric suction(digestive juice),，,excessive sweating(hypotonic solution with sodium),2)Renal loss of Na,+,:,Adrenocortical insufficiency(Addisons disease),Inappropriate long-term use of diuretics:Some diuretics(e.g.Frusemide)inhibit the Na,+,reabsorption in renal tubules.,Acute kidney faliure(diuretic phase),Renal tubular acidosis:,Dysfunction of H+-Na+exchange leads to a decrease of H+secretion,the urinary Na+excretion is increased.,3)other way that increase the extrarenal sodium loss:,Serious burn,body fluid accumulation in the“third space”(peritonitis),(3)Alterations of metabolism and function,1)Adaptive responses,Aldosterone secretion is stimulated by the low sodium concentration,except in the case of adrenocortical insufficiency,.,Normal,Interstitial fluid,Intracellular fluid,Plasma,2)Characteristic effect of hypotonic dehydration on the body,urine,specific,urine,volume gravity Na,+,-,early ADH,or,stage ALD,late ADH,stage ALD,-,(,注：经肾失钠的低渗性脱水，尿钠不减少,),sodiun loss through kidneys:urine sodium concentration increrase,Urine,Hypotension even shock,Extracellular fluid sodium concentration decrease.Then water transport from interstitial fluid to intracellular fluid.ECF decrease.,The blood pressure may decrease.Postural hypotension and shock will occur because the decreased blood volume.,(urine doesnt decrease at the early stage and water shifts into the cells),Severely reduced interstitial fluid(dehydration sign),Decreased fluid in the skin tissue results in the reduce of skin elasticity.When the skin is pinched,it tends to remain in fold.,Eyeball tension is decreased,the eyeballs are soft and sunken.,(low protein concentration and colloid osmotic pressure),Interstitial fluid,Intracellular fluid,Plasma,Intracellular overhydration,Water will shift from ECF to ICF because the ICF is relatively hypertonic.The cell will swell.,Brain cell overhydration produces brain dysfunction.(Cranial cavity is fixed),(severe headache,high brain pressure,nausea,vomitting,confusion and coma),Note:If the hyponatremia lasts over a long time,there will be an adaptive loss of solutes from ICF.This response mitigates the brian cell swelling.,There is no obvious thirst at early stage because of the low crystal osmotic pressure.,(4)Principles of treatment,Cure the primay disease(correct the sidium loss),Replacement of isotonic saline(0.9%NaCl)first.,Replacement of hypertonic fluid may lead to hypertonic state.,Pure water is easy to loss via skin and lung.,Hyperosmotic fluid are seldom used,except in urgent state of brain edema.,3.Isotonic Dehydration,(,1)Concept,There is loss of fluid(dehydration),the water loss is equal to salt loss.The ECF in the body is isotonic.,The Na,+,is 130145 mmol/L.,The osmolarity is 280310 mOsm/L.,2)Causes,(a)Loss of fluid is caused by vomiting,diarrhea,hemorrhage and from the burned area.,(b)The isotonic dehydration can be induced from hypertonic and hypotonic dehydration by the renal regulation.,3)Adaptive responses,The main change in isotonic dehydration is the reduced volume of ECF.,(a)It stimulates the thirst,so that the patient will ask to drink water to replace the volume of ECF.,(not as strong as hypertonic dehydration),(b)ADH release is stimulated,so that the water reabsorption will increase to replace the volume of ECF.(,not as much as hypertonic dehydration),(c)Secretion of aldosterone is increased due to hypovolemia.,(not as much as hypotonic dehydration),4)Effect on the body,(a)Urine volume is diminished because of the decreased GFR,increased ADH and aldosterone secretion.,(b)No water shift and related symptoms and signs.,(c)Poor skin,elasticity,and sunken eyeball,because of the reduction of interstitial fluid.,5)Principle of treatment,Hypotonic saline is needed to replace the fluid deficiency.,III.Overhydration,According to the sodium concentration:,Hypertonic overhydration,(2)Hypotonic overhydration(,water intoxication),(3)Isotonic overhydration,(edema),(I)water intoxication(Hypotonic overhydration),1 Concept,Excessive fluid in the body is called overhydration.,Excessive hypotonic fluid in the body is called hypotonic overhydration(water excess).,Severe water excess causes a serial of symptoms and signs,and is called water intoxication.,2 Causes,The main causes are excessive water intake and less loss of water.,(a)Excessive water intake,Excessive venous infusion of 5%glucose solution.,Excessive water intake of psychotic disturbances(e.g.schizophrenia)may