Glomerular diseases Flashcards
What are glomerular diseases? What two types are there?
Diseases of the glomeruli
Glomerulonephritis: inflammation of the glomeruli
Glomerulopathies: non-inflammatory disease of glomeruli
What is a glomerulus?
Draw the structure of a nephron + glomerulus.
A network of capillaries located at the beginning of a nephron in the kidney, next to the Bowman’s capsule
http://www.ivyroses.com/HumanBody-Images/Urinary/Kidney_Nephron_cIvyRose.png
What is focal glomerular disease?
When some but not all the glomeruli are affected
What is diffuse glomerular disease?
When most of the glomeruli are affected
What is segmental glomerular disease?
When only part of each glomerulus is affected
What is proliferative glomerular disease?
There is hyperplasia of the glomerular cells (increase in cell numbers)
Describe the structure of a glomerulus?
Afferent arteriole gives rise to the capillary bundle, which gives rise to the efferent arteriole
The capillary bundle is next to/within the Bowman’s capsule
The capillary endothelium is specialised for filtration
Podocytes are cells that surround each capillary vessel
Between the capillaries is the mesangium
The macula densa is found between the afferent and efferent arterioles at the point they enter the Bowman’s capsule, adjacent to this is the ascending limb of the nephron
What is the mesangium?
What does it do?
The space between the cells of a glomerulus is occupied by mesangial cells.
They are not part of the filtration barrier
The cells participate indirectly in filtration by contracting and reducing the glomerular surface area, and therefore filtration rate, in response mainly to stretch
What do podocytes do?
They are an extra barrier to aid filtration
They have slits
They are able to contract and reduce the filtration rate by closing their slits
What is the macula densa?
What does it do?
It is found between to the ascending limb of the nephron and the afferent + efferent arterioles
It is a network of specialised cells
Which are sensitive to the concentration of NaCl in the thick ascending limb. Low NaCl indicates GFR is too low
A decrease in NaCl concentration initiates a signal from the macula densa
The signal causes dilation of the afferent arterioles resulting in increased blood flow through glomerulus, increasing the GFR
The signal also increases renin release from the juxtaglomerular cells of the afferent and efferent arterioles, which are the major storage sites for renin
What are the juxtaglomerular cells?
Cells that store renin and are found next to the afferent and efferent arterioles
What is the difference between the afferent and efferent arterioles?
Afferent: brings blood to the glomerulus
Efferent: takes blood away from the glomerulus
Remember the Latin: ex = from, ad = to
Pyelonephritis and glomerulonephritis can be easily confused. What is the difference?
Pyelonephritis: infection in the urinary system, can only affect one kidney
Glomerulonephritis: autoimmune disease, autoantibodies attack the glomerulus, always affects both kidneys since it’s a systemic disease
What evidence is there that glomerulonephritis is an immune condition?
Deposits of immunoglobulin are found in the kidneys
Inflammatory cells are found: macrophages, neutrophils
Positive response to immune system treatment
What two syndromes can glomerulonephritis result in?
Nephritic Syndrome
Nephrotic Syndrome
One or both
What can glomerulonephritis cause?
Leaky glomeruli: protein and haematuria
Hypertension
Deteriorating kidney function
Why does glomerulonephritis cause hypertension?
Because inflammation causes damage and thus reduced renal perfusion
The body compensates by raising blood pressure
What is acute nephritic syndrome?
A group of symptoms that occurs in some cases of glomerulonephritis
Destruction of epithelial barrier lining the glomeruli
What are the clinical features of acute nephritic syndrome?
Haematuria
Proteinuria
Hypertension, raised JVP
Oliguria
Oedema: peripheral + pulmonary
Uraemia
What are some diseases associated with the development of acute nephritic syndrome?
ANCA associated vasculitis
Streptococcal infection
Goodpasture’s disease
SLE
Systemic Sclerosis
Henoch Schoenlein purpura
How does ANCA associated vasculitis cause damage to the kidneys?
ANCA: anti-neutrophil cytoplasmic antibodies
Attack the small blood vessels including the glomeruli, cause necrosis of blood vessel walls
Inflammatory cells infiltrate
How do you treat ANCA associated vasculitis?
Immunosuppression
Steroids
Rituximab
What does ANCA stand for?
Anti-neutrophil cytoplasmic antibodies
How does a streptococcal infection cause damage to kidneys?
Sometimes, after a Strep infection immune complexes (antigen-antibody) are deposited in the kidney
Classically it’s a tonsillitis infection
