Renal diseases Flashcards
What are the cells of the visceral layer in the bowmans capsule known as?
Filtration slits
What does it mean that the plasma membrane of the endothelial cells are fenestrated?
It has pores each covered with a thin membrane
Does albumin cross the basement membrane?
Only a small fraction (it is small enough but it is negatively charged and repelled)
What is the glomerular filtration rate?
Amount of filtrate produced by kidneys/minute (usually 120-125mL/min)
What is the effect of an increase in blood pressure on the GFR?
It would increase (by increasing the hydrostatic pressure)
What is the effect of dehydration on the GFR?
It would decrease (total blood volume has dropped)
What is the effect of obstructions to urine flow on the GFR?
It would decrease (increasing capillary hydrostatic pressure)
What is the effect of glomerular loss on the GFR?
It would decrease
How do you calculate clearance?
(subU/subP) x urine volume secreted
What is creatinine?
A waste product from energy metabolism in muscle (rate of production determined by total muscle mass)
Why is creatine useful for clearance?
- readily filtered
- not reabsorbed
- insignificant amount secreted by tubules
What is wrong with creatinine clearance?
- 24hr urine prone to error
- often estimate under actual clearance
solution: equations using only serum creatinine level
What are the 3 categories of glomerular disorders?
- immunological (glomerulonephritis)
- non-immunological (diabetic glomerulosclerosis)
- inherited (types of nephrotic syndrome)
What is glomerulonephritis?
Conditions with an inflammatory basis
What occurs with glomerulonephritis?
- Damage to the endothelium
- Dramatic changes in the permeability of filtration (allows RBC)
- Decreases in GFR
What are causes of glomerulonephritis?
Accumulation of antibodies
- Induced by infectious agents + antibodies being trapped
- Induced by binding of antibodies to membrane
What are the 5 clinical manifestations of glomerulonephritis?
- Decrease urine output
- Hypertension
- Haematuria + RBC
- Protein in urine
- Azotaemia (high blood urea)
Why does glomerulonephritis cause hypertension?
Less plasma leaves the capillary = greater blood volume
What is nephrotic syndrome?
An increased glomerular permeability to protein
How is nephrotic syndrome diagnosed?
Substantial proteinuria (>3.5g/day) accompanied with: -Hypoalbuminaemia + oedema -Lipiduria -Hyperlipidaemia
What is the mechanism behind primary defects in nephrotic syndrome?
(Inherited)
-minimal change disease where podocytes are absent
What is the mechanism behind secondary defects in nephrotic syndrome
Autoimmune disease e.g. lupus or diabetes mellitus
What is the mesangium?
network of fibres and cells that hold the glomerulus together
what are the 2 types of mesangial cells?
- Phagocytic cells (engulf material that pass through fenestrations but not slits)
- Contractile (reduce SA for filtration)
What is diabetic glomerulosclerosis?
- Increased GFR + permeability to protein
- Loss of nephrons
What occurs in the early stages of DG?
microalbuminuria (24hr excretion of 30-300mg)
- Poor prognosis
- indicator of cardiovascular disease
What is chronic kidney disease?
- irreversible renal damage
- drop in GFR
- Often death due to cardiovascular complications before end stage kidney disease
When do symptoms and signs become obvious in CKD?
when GFR < 50%
What are risk factors for CKD?
- Hypertension
- Diabetes
- Smoking
- BMI > 30
- Family history
- > 50
What are some clinical manifestations of CKD? (1)
- Loss of sodium balance
- Elevated blood K+ levels (cardiac arrhythmia)
- Depleted blood bicarb level + impaired H+ secretion (metabolic acidosis)
What are some clinical manifestations of CKD? (2)
- Chronic loss of renal supportive tissue
- Increase in phosphate, less calcum
- Less vitamin D (calcitriol)
- PTH attacks bones
What is a complication of CKD?
Renal rickets / osteodystrophy
What is a haematological disorder of CKD?
Erthropoietin production is insufficient (worsens with elevated blood urea nitrogen)
- Less RBC
- Leads to anaemia
What are skin disorders of CKD?
- Dry skin + mouth
- Disorders due to deposition of phosphate + urea crystals (pruritis)
What is uraemia?
Azotaemia (elevated BUN))
What can uraemia cause (6)
-Hypertension, nausea, vomiting, anorexia, peripheral neuropathy (restless leg), uraemic encephalopathy (alertness)
