Pathology

of the

Urinary System

Lecture-2

Recap..

Anatomy and physiology of kidney

Structure of nephron and components

Functional aspects

Clinical aspects

Pathogenesis

Recap..

Glomerular basement membrane:

• 320 nm thick in adults

• Central lamina densa

• Lamina rara on either side.

• Contains in addition to IV collagen and other

components, polyanionic proteoglycans.

• Plays a very important role in charge

dependant filtration. Does not allow anions

(proteins) but allows water and cations

Recap..

Filtration barrier of glomerulus:• Fenestrated endothelial cells (70-100 nm)• Glomerular basement membrane• Filtration slits of podocyte (20-30 nm)

Size dependant and charge dependant filtration.Allows particles below 3.5 nm to pass. Restricts albumin (3.6 nm) and other proteins.

Recap..

Juxta-glomerular apparatus:

• JG cells of afferent arteriole

• Macula densa of DCT

• Lacis cells of mesangium

Important source of renin

Plays a role in hypertension

Clinical syndromes related to renal disease

Chr renal failure

Ac renal failure

Nephrotic synd

Acute nephritis

Clinical syndromes related to renal disease

Chr renal failure

Ac renal failure

Nephrotic synd

Acute nephritis

Clinical syndromes related to renal disease

Hematuria, proteinuria, hypertension

Chr renal failure

Ac renal failure

Nephrotic synd

Acute nephritis

Clinical syndromes related to renal disease

Hematuria, proteinuria, hypertension

Proteinuria > 3.5 g/day, hypoalbuminemia <2 g/dl, edema, hyperlipidemia, lipiduria

UremiaChr renal failure

Oliguria / anuria, azotemia, (Anuria <100 ml; oliguria 100-400 ml)

Ac renal failure

Proteinuria > 3.5 g/day, hypoalbuminemia <2 g/dl, edema, hyperlipidemia, lipiduria

Nephrotic synd

Hematuria, proteinuria, hypertensionAcute nephritis

Clinical syndromes related to renal disease

Pathogenesis of Glomerulonephritis

Pathogenesis of glomerulonephritis

Immune mechanisms underlie majority of the primary glomerulonephritis1. In situ immune complex deposition

a. Intrinsic (fixed) glomerular antigensAnti GBM, Heymann nephritis, membranous nephropathyb. Planted antigens (proteins, bacterial, viral)

2. Circulating immune complexes

Others: cytotoxic antibodies, chemical mediators, cell mediated injury, non-immune mechanisms.

Glomerular response to injury

• Glomerulus responds to a variety of injuries in a very limited

manner

• Hypercellularity - mesangial, endocapillary, extracapillary

(crescents), exudation

• Basement membrane changes

• Sclerosis

• Others - Necrosis, deposits of fibrin, abnormal proteins, etc.

Diffuse: All glomeruli in the biopsy / kidney are

affected

Focal: Only few glomeruli are affected (<50%)

Global: The entire glomerulus is involved

Segmental: Only part of the glomerulus (few tufts) are

involved

Terminology

Diffuse changes

Focal changes

Global changes

Segmental changes

Less than 80% of glomerular surface is involved