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Kidney

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Kidney

Kidney

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  • 1. KidneyKidney The kidney performs excretory & endocrinal functions such asThe kidney performs excretory & endocrinal functions such as ;eliminate waste products from the body, regulate both;eliminate waste products from the body, regulate both erytheroposis, arterial blood pressure .are essential forerytheroposis, arterial blood pressure .are essential for homeostasis (regulation of body water content) .the blood levels ofhomeostasis (regulation of body water content) .the blood levels of both electrolyte and non electrolytes, and the acids base balanceboth electrolyte and non electrolytes, and the acids base balance.. Excretory functions of the kidney;Excretory functions of the kidney; thethe kidney clear the plasma from unwantedkidney clear the plasma from unwanted substance which includes; Non essentialsubstance which includes; Non essential substance ,end products of metabolism assubstance ,end products of metabolism as urea ,uric acids and creatinin & bilirubinurea ,uric acids and creatinin & bilirubin Foreign substance as drugs ,toxinsForeign substance as drugs ,toxins.. Excess amount of essential substanceExcess amount of essential substance ;water, electrolyte (na ,k;water, electrolyte (na ,k(.(.
  • 2. Endocrine function of the kidneyEndocrine function of the kidney They secret rennin & erythropoietin, and form prostaglandins,1-25They secret rennin & erythropoietin, and form prostaglandins,1-25 dihydroxycholecalciferoldihydroxycholecalciferol.. RenninRennin This is secreted by juxtaglomerular cells .It is glycoprotein's which is acts onThis is secreted by juxtaglomerular cells .It is glycoprotein's which is acts on angiotensinogen ( which is synthesized by the liver ) leading to formation ofangiotensinogen ( which is synthesized by the liver ) leading to formation of angiotensin1angiotensin1 which is converted towhich is converted to angiotensin11angiotensin11 which producewhich produce several effects :generalized vasoconstriction , stimulation of aldosteroneseveral effects :generalized vasoconstriction , stimulation of aldosterone formationformation.. Rennin secretion is stimulated by renal ischemia ,in case of hypotension.,Rennin secretion is stimulated by renal ischemia ,in case of hypotension., increased sympathetic activity and by certain prostaglandinsincreased sympathetic activity and by certain prostaglandins.. ErythropoietinErythropoietin It is a glycoprotein ,secreted by endothelial cell of peritubular capillaries in theIt is a glycoprotein ,secreted by endothelial cell of peritubular capillaries in the renal cortexrenal cortex.. It is increase number of committed stem cell in the bone marrow that isIt is increase number of committed stem cell in the bone marrow that is converted into red cell precursor and subsequently into mature red bloodconverted into red cell precursor and subsequently into mature red blood cellscells.. It is secretion is stimulated by hypoxia ,cobalt salts, androgens and is facilitateIt is secretion is stimulated by hypoxia ,cobalt salts, androgens and is facilitate by adenosine catecholamine, and by alkalosis. That develop at high altitudeby adenosine catecholamine, and by alkalosis. That develop at high altitude
  • 3. ProstaglandinProstaglandin Act on auto regulation of glomerular filtration rate &Act on auto regulation of glomerular filtration rate & renal blood flow and stimulate rennin secretionrenal blood flow and stimulate rennin secretion The kidney secretes two types of prostaglandins : PGThe kidney secretes two types of prostaglandins : PG 1& PG111& PG11.. 1,251,25 DihydroxycholechalciferolDihydroxycholechalciferol;; This is active form of vitamin DThis is active form of vitamin D It is formation is facilitated by parathyroid hormonesIt is formation is facilitated by parathyroid hormones It is released into the blood stream where it produce itsIt is released into the blood stream where it produce its effects in the intestine and boneeffects in the intestine and bone..
  • 4. Renal circulationRenal circulation The kidney receive the arterial blood via the renal artery which arises directly from aortaThe kidney receive the arterial blood via the renal artery which arises directly from aorta it breaks into interlobar arteries in the medulla break into interlobular which inter theit breaks into interlobar arteries in the medulla break into interlobular which inter the cortex and then divide into interlobularcortex and then divide into interlobular Renal blood flowRenal blood flow Normally R.B F is about 1200ML/Minute, the flow is much greater in the cortex ,onlyNormally R.B F is about 1200ML/Minute, the flow is much greater in the cortex ,only about 2% pass in the vasa recta resulting in a sluggish flow in the renal medulla ,about 2% pass in the vasa recta resulting in a sluggish flow in the renal medulla , which is important in the process on urine formationwhich is important in the process on urine formation.. Control of R .B FControl of R .B F R .B .FR .B .F IsIs directly proportionaldirectly proportional toto A.B PA.B P .↑RBF ↑ABP.↑RBF ↑ABP And inversely proportional to renal vascular resistance (R.V.R)And inversely proportional to renal vascular resistance (R.V.R) which is determined by the diameter of glomerular afferent &which is determined by the diameter of glomerular afferent & efferent arterioleefferent arteriole.. Catecholamine'sCatecholamine's ,strong sympathetic stimulation cause renal,strong sympathetic stimulation cause renal vasoconstriction specially the afferent arteriole lead to ↑RVR sovasoconstriction specially the afferent arteriole lead to ↑RVR so leads to ↓R B Fleads to ↓R B F.. Acetyl choline & other vasodilator drugsAcetyl choline & other vasodilator drugs ,caffeine ,↑RBF,caffeine ,↑RBF leads to ↓RVRleads to ↓RVR.. ProstaglandinsProstaglandins ↑blood flow in the renal cortex & ↓in the renal↑blood flow in the renal cortex & ↓in the renal medullamedulla.. AngiotensinAngiotensin cause vasoconstriction particularly the efferentcause vasoconstriction particularly the efferent arteriole leads to ↑RVR &↓RBFarteriole leads to ↑RVR &↓RBF..
  • 5. __Renal blood flowRenal blood flow The renal blood flow can be measure by either: 1- ElectromagneticThe renal blood flow can be measure by either: 1- Electromagnetic.. 22--Determination of renal plasma flow 3-.Haematocriet valueDetermination of renal plasma flow 3-.Haematocriet value Renal plasma clearanceRenal plasma clearance It is the amount of plasma in ml which is cleared off or removed from a certain substanceIt is the amount of plasma in ml which is cleared off or removed from a certain substance per minutes by both kidneysper minutes by both kidneys.. c=uxv/pc=uxv/p C=Renal plasma clearanceC=Renal plasma clearance.. U=Urine concentration of the substance ⁄ mg ⁄mlU=Urine concentration of the substance ⁄ mg ⁄ml V = Volume of urine in ml/min which is determined by introducing catheter intoV = Volume of urine in ml/min which is determined by introducing catheter into urinary bladderurinary bladder.. P= plasma con of substance in mg/mlP= plasma con of substance in mg/ml This equation is called( Ficks principle ) methodsThis equation is called( Ficks principle ) methods.. The clearance value in not the same depending upon what is happen in theThe clearance value in not the same depending upon what is happen in the nepheronnepheron.. Substance that are secreted by the renal tubules have high clearance value,Substance that are secreted by the renal tubules have high clearance value, while those reabsorbed have low clearance valuewhile those reabsorbed have low clearance value.. If the substance is secreted from the tubules, the clearance value will be higherIf the substance is secreted from the tubules, the clearance value will be higher than inulin clearance , if the secretion is complete the clearance valuethan inulin clearance , if the secretion is complete the clearance value equals 700ml/minequals 700ml/min If clearance value more than 700 ml/ min this means that the substance isIf clearance value more than 700 ml/ min this means that the substance is synthesized by the tubulessynthesized by the tubules..
  • 6. Inulin clearanceInulin clearance It is used to measure glomerular filteration rate (G.F.RIt is used to measure glomerular filteration rate (G.F.R(.(. Inulin is a polymer of fructose with low molecular weight .it isInulin is a polymer of fructose with low molecular weight .it is neither reabsorbed nor secreted, but it is freely filtered , it is notneither reabsorbed nor secreted, but it is freely filtered , it is not toxic, it is freely permeable by the glomeruli, it is not utilized bytoxic, it is freely permeable by the glomeruli, it is not utilized by the tissue., it is not enter the red cellsthe tissue., it is not enter the red cells.. It is easily measure in plasma so its concentration in plasma = itsIt is easily measure in plasma so its concentration in plasma = its concentration in filtratesconcentration in filtrates Also the amount of inulin filtered /min = its amount excreted inAlso the amount of inulin filtered /min = its amount excreted in urine/minurine/min.. The inulin clearance is about 130 ml/minThe inulin clearance is about 130 ml/min Significance ; measure G.F.RSignificance ; measure G.F.R..
  • 7. Determination of renal blood flowDetermination of renal blood flow It is used by two substanceIt is used by two substance;; 11--DiodrastDiodrast.. 22--PAHA(para-amino-hipuric –acidsPAHA(para-amino-hipuric –acids(( When these substance are present in certainWhen these substance are present in certain concentration in plasma not more than 2mg/ml plasmaconcentration in plasma not more than 2mg/ml plasma they are completely removed by the kidneythey are completely removed by the kidney.. Sample of renal venous bloodSample of renal venous blood can be obtained incan be obtained in man by introducing a cardiac catheter into cubital veinman by introducing a cardiac catheter into cubital vein to the right atrium to inferior vena cava to renal veinto the right atrium to inferior vena cava to renal vein.. Renal venous blood contain traces of PAHARenal venous blood contain traces of PAHA.. Renal plasma flowRenal plasma flow= 14(con of PAHA in urine ) /= 14(con of PAHA in urine ) / 0.02(con of PAHA in plasma )=700ml/min0.02(con of PAHA in plasma )=700ml/min Renal blood flowRenal blood flow = Renal plasma flow X 1/1-HV= Renal plasma flow X 1/1-HV ==700X1/1-0.55=700X1/1-0.55=1273ml/min1273ml/min..
  • 8. Creatinine clearanceCreatinine clearance It is freely filtered in the glomeruli then partially secreted in theIt is freely filtered in the glomeruli then partially secreted in the proximal convoluted tubule ,and it is not reabsorbedproximal convoluted tubule ,and it is not reabsorbed.. Because creatinine is partially secreted ,the excreted amount inBecause creatinine is partially secreted ,the excreted amount in urine uxv is more than filtrates , normally 140 ml/minurine uxv is more than filtrates , normally 140 ml/min.. TestTest:: Creatinine clearance depend on the daily product of creatinineCreatinine clearance depend on the daily product of creatinine (produce from muscle metabolism )which is constant and not(produce from muscle metabolism )which is constant and not affected by protein intakeaffected by protein intake.. UrineUrine is collected over 24 hours for measure of urinaryis collected over 24 hours for measure of urinary creatininecreatinine.. Blood plasmaBlood plasma are taken through the day .average plasma isare taken through the day .average plasma is determined about 3 samples,one in the morning ,onedetermined about 3 samples,one in the morning ,one afternoon ,one in the evening .because its varies during the dayafternoon ,one in the evening .because its varies during the day according to ms exercise .creatinine clearance is determinedaccording to ms exercise .creatinine clearance is determined ImportanceImportance;; With progressive renal failure decrease creatinine clearanceWith progressive renal failure decrease creatinine clearance..
  • 9. Urea clearanceUrea clearance IT is freely filtered in the glomeruli .then partially reabsorbed (back diffusion) InIT is freely filtered in the glomeruli .then partially reabsorbed (back diffusion) In the tubules and it is not secretedthe tubules and it is not secreted Because urea is partially reabsorbed ,the excreted amoumt in the urine is lessBecause urea is partially reabsorbed ,the excreted amoumt in the urine is less than filtered .so its clearance value will be smaller than inulin clearance .thethan filtered .so its clearance value will be smaller than inulin clearance .the amount of excreted urea depend upon the rate of urine flow ,the greater theamount of excreted urea depend upon the rate of urine flow ,the greater the urine flow the less will be the back diffusion &the more will be the amount ofurine flow the less will be the back diffusion &the more will be the amount of urea excretedurea excreted.. If the volume of urine is 2ml or moreIf the volume of urine is 2ml or more ,the excretion of urea is maximal and the,the excretion of urea is maximal and the usual formula of plasma clearance test is usedusual formula of plasma clearance test is used 75ml/min75ml/min If the volume is 2 mlIf the volume is 2 ml the standard clearance formula is used .c=uxv/Pthe standard clearance formula is used .c=uxv/P TestTest 11--The subject evacuate his bladder ,then he drink a glass of waterThe subject evacuate his bladder ,then he drink a glass of water.. 22--One hour later a blood sample is taken(, to measure p),Urine is collectedOne hour later a blood sample is taken(, to measure p),Urine is collected and he drink another glass of waterand he drink another glass of water.. 33--After another hour, urine is again collected and average volume /min & ureaAfter another hour, urine is again collected and average volume /min & urea are calculatedare calculated.. If v is 2ml or more maximal clearance is usedIf v is 2ml or more maximal clearance is used If v is less than 2 ml standard clearance formula is usedIf v is less than 2 ml standard clearance formula is used.. C= uC= ux√v/p=54ml/minx√v/p=54ml/min