15.8 Kidney Failure Flashcards
What are the causes of kidney failure?
• Damaged structures
(E.g Bowman’s capsule, podocytes, basement membrane)
• Genetics
(E.g polycystic kidney disease)
What are the effects of infection/high blood pressure on the kidneys?
• Protein/erythrocytes in urine
(∵ basement membrane/podocytes are DAMAGED from high pressure, no longer act as FILTERS, allow LARGE MOLECULES through to filtrate)
What are the effects of kidney failure?
- ￪ UREA concentration (urea cannot be excreted, builds up)
- Imbalanced ELECTROLYTES (excess ions not excreted, leads to osmotic imbalances)
- High BLOOD PRESSURE (excess ions decrease water potential, water moves in, increased hydrostatic pressure)
- WEAKENED BONES (imbalanced calcium + phosphorus)
- PAIN + STIFFNESS (build up of abnormal proteins in blood)
- ANAEMIA (kidneys no longer produce enough erythropoietin, cannot make enough erythrocytes)
Why is increased urea concentration an effect of kidney failure?
Urea can no longer be excreted
∴ builds up
Why is an imbalance of electrolytes an effect of kidney failure?
Excess ions (K+, Na+, Cl-) cannot be excreted.
leads to osmotic imbalances + eventual death
Why is high blood pressure an effect of kidney failure?
Excess ions (which cannot be excreted) decrease water potential of blood
water moves in from surrounding tissue by osmosis
increases hydrostatic pressure of blood
Why is weakened bones an effect of kidney failure?
Imbalanced calcium and phosphorus
responsible for healthy bones and teeth
Why is pain & stiffness an effect of kidney failure?
Accumulation of abnormal proteins in the blood
which would otherwise be excreted
Why is anaemia an effect of kidney failure?
Kidneys are involved in production of erythropoietin,
which makes erythrocytes.
Failed kidneys dont produce enough erythropoietin,
∴ not enough erythrocytes (anaemia)
What is the glomerular filtration rate an indicator of?
kidney function
How is GFR (glomerular filtration rate) measured?
Indirectly, by measuring creatinine levels
What is creatinine and how is it used?
product of muscle breakdown.
Creatinine levels in blood measured to indicate glomerular filtration rate.
(Since usually filtered out of blood by kidneys, an abnormal level of creatinine in the bloodstream indicates insufficient kidney function + possible disease)
What must be taken into account when measuring glomerular filtration rate using creatinine?
other factors affecting creatinine levels, e.g age, gender
What 2 different treatments are there for kidney failure?
- DIALYSIS 2. TRANSPLANT
What are the 2 types of renal dialysis?
- HAEMODIALYSIS
* PERITONEAL DIALYSIS
How does haemodialysis work?
- Blood leaves through artery ⟶ dialysis machine
- Blood + dialysis fluid flow on either side of PARTIALLY PERMEABLE MEMBRANE in COUNTERCURRENT
• DIFFUSION of solutes occurs between blood + dialysis fluid
◦ Urea removed
◦ Salt + mineral ion levels balanced
◦ No net movement of glucose
Why is blood thinner added to the blood during haemodialysis?
to prevent blood clotting
How are air bubbles removed from the filtered blood during haemodialysis?
blood passes through bubble trap before re-entering patient.
air bubbles in blood can cause heart attack
What concentration of urea does dialysis fluid initially contain in relation to the blood?
dialysis fluid initially contains NO UREA
to provide steepest concentration gradient for urea to diffuse out of blood
Why does the blood and dialysis fluid travel in a countercurrent during haemodialysis?
In which other topics can a countercurrent be found?
to prevent reaching equilibrium.
(where concentration gradient is no longer steep enough for net diffusion of solutes to occur.)
- Mother’s blood + foetal blood flows in countercurrent in placenta during diffusion of oxygen.
- Solutes in descending + ascending loop of Henle run in countercurrent.
- water and blood flow in fish gills runs in countercurrent
etc
What concentration of salt and mineral ions does dialysis fluid initially contain in relation to the blood?
dialysis fluid initially contains the desired concentration of salt and mineral ions
so that the salt + mineral ion concentration in the blood can be balanced by diffusion
What are the advantages and disadvantages of haemodialysis?
• ADVANTAGES
◦ no invasive surgery
◦ no permanent catheter
◦ no immunosuppressants
• DISADVANTAGES
◦ must undergo dialysis @ hospital several times a week for several hours
◦ Must manage diets carefully
How does peritoneal dialysis work?
- Dialysis fluid introduced into abdomen using catheter
- DIFFUSION occurs between dialysis fluid + blood across peritoneal membrane.
- Used dialysis fluid enters + stored in bag.
What are the advantages and disadvantages to peritoneal dialysis?
ADVANTAGES
• less regulation of diet
• No lengthy hospitalisation
DISADVANTAGES
• must have catheter inserted into abdomen
• peritonitis - infection of the peritoneal membranes
What are the advantages and disadvantages to treating kidney failure with a transplant?
ADVANTAGES
• does not disrupt daily life
• lasts many (10) years
DISADVANTAGES • must wait for DONOR • risk of REJECTION (minimised by matching antigens using tissue samples, & using immunosuppressants) • IMMUNOSUPPRESSANTS must be taken daily • INVASIVE SURGERY - risk of infection
