15.8 Kidney failure Flashcards
what are the reasons for kidney failure (3)
- kidney infection (podocyte/tubule structure damaged)
- raised blood pressure (damage epithelial cells and basement membrane)
- genetic conditions
what does polycystic kidney disease do
- genetic
- healthy kidney tissue is replied by fluid-filled cysts or damaged by pressure from cysts
what effect does high blood pressure have on the kidney
- protein in urine (basement membrane/podocytes are damaged so can’t filter correctly)
- blood in the urine (filtered incorrectly)
what are the effects of urea and mineral ion conc building up due to kidney failure (6)
- loss of electrolyte balance
- build-up of toxic urea in blood
- high blood pressure
- weakened bones
- pain + stiffness in joints
- anaemia
how does a loss of electrolyte balance happen
- body cannot excrete excess sodium, potassium and chloride ions
- causes osmotic imbalances in tissues
- eventual death
why do bones get weaker if they kidneys fail
calcium/ phosphorus balance is lost in the blood
what causes anaemia
- kidneys produce hormone called erythropoietin which stimulates production of RBCs
- kidney failure = less production of RBCs
- causes tiredness and lethargy
how is GFR used to indicate kidney disease
- blood test measures creatinine
- is a breakdown product of muscles and gives estimated GFR
- high levels indicate kidneys aren’t working properly
what are the units for eGFR
cm3/min
what factors need to be considered when calculating GFR
- decreases steadily with age even if healthy
- men have more muscles mass so more creatinine
what do GFR levels of 60 and 15 indicate
- below 60 for 3 months = chronic kidney disease
- below 15 = kidney failure
what is haemodialysis
blood is removed and passed through a machine containing an artificial dialysis membrane which allows counter-current exchange
explain the process of haemodialysis
- blood leaves from artery into dialysis machine
- flows between a partially permeable dialysis membrane (mimics basement membrane)
- patients lose excess urea and some mineral ions
- dialysis fluid has normal plasma levels of mineral ions so if there is a shortage they move down a conc gradient into the blood
- no urea in dialysis fluid so it goes out of the blood due to steep conc gradient
- countercurrent system as blood and fluid flow in opposite directions
how long does haemodialysis take
- 8 hours
- repeated several times a week
how is the diet controlled for haemodialysis
- diet and fluids are monitored
- can only eat/drink at the start of the process to avoid forming excess urea
what is peritoneal dialysis
- makes use of the natural dialysis membranes formed by the abdomen lining (peritoneum)
- done inside the body
- done at home and patient carries on with normal life
explain the process of peritoneal dialysis
- dialysis fluid introduced to the abdomen by a catheter
- left for several hours as dialysis takes place across the peritoneal membranes
- urea and excess mineral ions pass out of capillaries–> tissue fluid–> across peritoneal membrane–> dialysis fluid
- fluid is drained off and discarded
what happens in a kidney transplant
- new kidney is implanted into a patient’s body to replaced a damaged kidney
- blood vessels are joined
- ureter is inserted into the bladder
where can the kidney in a kidney transplant come from
- people with the same blood/tissue type (often living relative)
- people who have just died and donated their organs
what are possible problems of a kidney transplant
- operation can be risky
- immune system may reject the transplant as antigens in the patient’s immune system recognise the different antigens on he donor kidney and try to destroy them
what are solutions to avoid kidney transplant failure
- take immunosuppressant drugs for life (BUT harder to fight infectious diseases effectively)
- make a close match by using similar tissue and blood type
how long do transplanted kidneys averagely last
9-10 years
what happens if a kidney transplant fails
patient has to return to dialysis and wait for another suitable kidney to be found
advantages of dialysis
- more readily available
- patient can lead a relatively normal life
disadvantages of dialysis
- monitor diet carefully
- regular sessions on the machine
- long term is expensive and damages body
advantages of kidney transplant
- free of restrictions that come from regular sessions and diet monitoring
disadvantages of kidney transplant
- shortage of donor kidneys (many don’t register as donors and less sudden car deaths)
what is the hope for the future for kidney failure
grow functioning embryonic kidney tissue from stem cells perhaps even without antigens that trigger immune reaction
