Kidney Disease and Renal Failure Flashcards
Define “pre-renal acute kidney injury”
Sudden reduction in blood flow to the kidneys, causing a loss of kidney function . Nothing is wrong with the kidney itself
Define “post-renal acute kidney injury”
acute kidney injury caused by disease states downstream of the kidney and most often occurs as a consequence of urinary tract obstruction
What is the functional unit of the kidney?
Nephron
State the route which a filtrate takes as it passes through a nephron
Afferent arteriole Glomerulus Bowman's capsule Efferent arteriole Proximal convoluted tubule Descending loop of Henle Ascending loop of Henle Distal convoluted tubule Collecting duct
How can we express mathematically the three renal processes which comprise urine formation?
Urine excretion rate = Filtration rate - Reabsorption rate + Secretion rate
How does the Glomerular capillary membrane differ to other capillary membranes?
Normal capillary membranes have two layers: Fenestrated endothelium and basement membrane.
Glomerular capillary membranes have an additional layer of epithelial cells (podocytes), surrounding the outer surface
In the glomerular capillary membrane, there are large fenestrations in the endothelium. Why are large plasma proteins still not passed through?
The endothelial cells have fixed negative charges which prevent this
Discuss the structure of the podocytes
Podocytes encircle the outer surface of capillaries. They are seperated by gaps called slit junctions. They also have negative charges which provide additional restriction to filtration
What are the four characteristics of Nephrotic syndrome?
Peripheral oedema
Proteinuria
Hypoalbuminaemia
Hypercholesterolaemia
How is Nephrotic syndrome biochemically defined?
Proteinuria / Hypoalbuminaemia < 30g/L
What is the Macula Densa, and briefly what is its role?
It is a specialisation of the Distal Convoluted Tubule, and monitors level of NaCl in fluid of DCT
Outline the role of the Macula Densa if NaCl levels are low in the fluid
- Macula Densa releases renin from Juxtoglomerular cells, which cause an increase in angiotensin II and aldosterone
- Angiotensin II acts on the PCT
- Aldosterone acts on the collecting duct
- This stimulates NaCl and water reabsorption
What maintains capillary oncotic pressure?
Albumin
Define oncotic pressure
A pressure exerted by proteins i.e. albumin in a blood vessel’s plasma that tends to pull water into circulation
What are three main PRIMARY causes which can lead to Nephrotic syndrome?
(Tends to occur in children)
- Minimal change disease (MCD)
- Focal segmental glomerulosclerosis (FSGS)
- Membranous nephropathy (MN)
State some SECONDARY causes of Nephrotic syndrome?
Tends to occur in adults
- Diabetic nephropathy
- Systemic Lupus Erythematous
- Amyloidosis
- Cancer
- Chronic viral infection
State the four characteristics of Nephritic Syndrome
- Proteinuria
- Haematuria
- Oligouria
- Hypertension
State some conditions associated with Nephritic syndrome
Post-streptococcal glomerulonephritis
IgA nephropathy
Goodpasture’s syndrome
Outline how SLE can cause disease of the glomerulus
Autoantibodies form or are deposited in the glomeruli, causing complement activation, leading to inflammation
Outline how Goodpasture’s Syndrome can cause disease of the glomerulus
In situ autoantibodies in kidneys, causing inflammation
Outline how IgA nephropathy can cause disease of the glomerulus
IgA form deposits in the glomerulus, causing inflammation
Outline how Alport syndrome can cause disease of the glomerulus
Mutations in the collagen biosynthetic pathway, leading to dysfunctional collagen network production in the glomerulus and improper filtration
Outline how Post-streptococcal glomerulonephritis can cause disease of the glomerulus
Strep bacteria does not attack kidneys directly, but an infection may stimulate the immune system to produce antibodies which deposit in the glomeruli
Outline how diabetic nephropathy can cause disease of the glomerulus
Elevated glucose levels appear to increase speed of blood flow into kidney, putting a strain of glomerular filtration and raising blood pressure
Outline how Membraneous Nephropathy can cause disease of the glomerulus
Unusual deposits of IgG and complement C3 in the glomerulus
Chronic Kidney Disease can be divided into how many stages? What is the first and last stage?
Stage 1: Normal GFR Stage 2 Stage 3 Stage 4 Stage 5: < 15ml/min or RRT
