Presentation on theme: "Outline the problems that arise from kidney failure and discuss the use of renal dialysis and transplants for the treatment of kidney failure Kidney failure."— Presentation transcript:
1Outline the problems that arise from kidney failure and discuss the use of renal dialysis and transplants for the treatment of kidney failureKidney failure affects tens of thousands of people each year in the UKIf one kidney fails, one can survive with one functioning kidneyIf both kidneys fail, death will result within about 2 weeks without medical treatmentDeath often results from build up of potassium ions...... which causes heart failure
2Filters blood under pressure Damaged by excessive pressureAdjusts pH of bloodAdjusts water content of blood in response to ADHSelectively reabsorbs glucose, amino acids, vitamins, sodium and chloride ionsReabsorbs waterNOTE: regulation of water balance helps regulate blood volume which helps regulate blood pressure
3Chronic kidney failure Progressive, long term kidney failure – takes place over a number of yearsPossible causes:- Bacterial infection of pelvis and surrounding tissue- Nephritis: inflammation of glomeruli due to antibodies to other infections attacking tissue- Damage due to high blood pressure- Damage due to obstruction of ureter, bladder or urethra- Diabetes mellitus (sugar diabetes)- Atherosclerosis – reduces blood supply to kidney
4Chronic kidney failure Nephrons are progressively destroyed, leading to:- Reduced quantity of urine- Dilute urine- Dehydration- Salt imbalance- Severe high blood pressure- Coma and convulsions
5Acute kidney failureRelatively sudden failure of kidneyPossible causes:- Loss of blood supply to kidney...... possibly as a result of blood loss in accident ...... heart failure...... or toxic chemicals- Severe bacterial infection or nephritis- Physical damage to kidney- Obstruction of ureters, bladder or kidney
6Acute kidney failureLeads to:- Little or no urine produced- Accumulation of nitrogenous waste in blood- Salt imbalance- PainOften reversible if treated QUICKLY
7‘Renal Dialysis’ or ‘Haemodialysis’ Used to remove waste products such as urea, excess ions such as potassium and excess water from the blood when the kidneys are incapable of doing this
8Blood is passeddiverted through the dialysis machine.The dialyser containsa semi-permeable membrane made of cellulose acetate or nitrate (e.g. Visking tubing)Blood flows on one side of the dialysis membrane and a dialysis fluid flows on the other sideWaste materials and excess salts and water diffuse across the dialysis membrane into the dialysis fluid.
10The dialysing fluid is formulated to ensure that only waste products and excess substances diffuse across the membraneNote: for diffusion to occur, there must be a concentration gradient for the substance concerned to diffuse downThe dialysing fluid contains no urea or other excretory products, ensuring that these diffuse rapidlyA countercurrent system ensures that the concentration of urea etc is always higher on the blood side of the dialysis membrane
11The concentration of glucose, mineral ions and other useful The concentration of glucose, mineral ions and other useful substances is the same in the dialysing fluid as in normal blood plasmaThese substances will only diffuse across into the dialysis fluid if their levels in the plasma are above normal levelsThe dialysing fluid also contains dextran – a polysaccharide which cannot pass through the dialysing membraneThe level of dextran ensures that the water potential of the dialysing fluid is the same as normal plasmaIf the plasma contains excess water, this will move into the dialysing fluid by osmosis.
12If the blood and dialysing fluid flow in the same direction (concurrent flow), then the concentration gradient between adjacent regions of blood and dialysing fluid will drop as diffusion takes place along the length of the dialysing membrane10070455030FlowDiffusionGradientThis will cause the rate of diffusion to slow as we move along the length of the dialysing membrane
13In a counter-current system, the concentration gradient is maintained along the length of the dialysis membrane10080604020FlowDiffusionGradient
14Kidney transplantsFirst kidney transplants were performed in 1960’s~1800 transplants are performed each year in UKNumber of transplants is limited by:availability of donorsavailability of good tissue match with patientKidney transplants have high survival ratesTissue rejection is prevented with use of drugs such as cyclosporin A which damp the immune responseAs you only need one kidney, close relatives can act as donors (reduces risk of rejection)
15Kidney transplantsTransplants are cheaper than dialysis- Cost of dialysis was ~£20 000/year in mid 90’s- Post-transplant drug therapy cost ~£3000/yearQuality of life for patient is better if procedure is successful