W11L5 - Renal Pathology Flashcards
End Stage Kidney Disease (ESKD)
Most severe form of chronic kidney disease
To survive, patients usually require kidney replacement therapy (KRT)
KRT has 2 forms: kidney transplant or dialysis
Dialysis is an artificial way of removing waste substances from the blood and is mostly provided in hospitals or satellite dialysis units, but can also be provided in a home setting
Comorbidity
Chronic vascular disease (CVD), diabetes, and chronic kidney disease (CKD), are serious, chronic and long-lasting diseases
They have complex causalities where each of them may be associated with, or exacerbate the presence of, the others
This, combined with shared risk factors and pathologies, often results in CVD, diabetes and CKD occurring together in an individual - a condition known as comorbidity
Functions of the Kidney
Regulation of water electrolyte and acid base balance
Regulation of body fluid osmolarity
Regulation of arterial pressure
Secretion of and response to hormones
Excretion of metabolic wastes and xenobiotics
Anatomy of the Kidneys
Located in retro peritoneum between the upper border of the 12th thoracic vertebra and the 3rd lumbar vertebra
Surrounding each is a fibrous capsule
Peri renal fat encompasses the capsule and the fat is anchored to the posterior abdominal wall by Gerota’s fascia
Medial border - hilum permits entry and exit of vessels, nerves, lymphatics and renal pelvis’
Right kidney lower due to liver
Structural Anatomy of the Kidneys
Parenchyma consists of cortex and medulla
Cortex 1cm layer under the capsule and extends down to the pyramids
Medulla consists of the renal pyramids and is divided into the inner medulla and outer papilla regions
The papilla protrudes into the calyx - its tip has 20-70 openings of the papillary collecting ducts
Renal pelvis is sac like extension of the ureter
- 2 or 3 major calyces extend from the pelvis and divide into the minor calyces into which the papillae protrude
The ureters are approx. 30cm long and terminate in the lateral bladder
The Nephron
2.5 million: 85% cortical , 15% juxtaglomerular
L~4cm, total length 50km
Glomerulus = tuft of capillaries that loop into the Bowman’s capsule forming the renal corpuscle and the Bowman’s space
Mesangial cells and mesangial matrix lie between the capillary loops; have SmM contractile properties
- modulate glomerular filtration, shape & phagocytose macromolecules in the mesangium
- have a contribution in diabetic nephropathy
Glomerulus
The PCT at the urinary pole consists of a single layer of cuboidal cells that have a brush border
PCT joins LoH that extends into the medulla
LoH has a thin medullary descending and a thick cortical ascending segment
- thin - no active transport
- thick - transports solutes
DCT extends from the macula densa to the collecting duct
DCT principal cells reabsorb Na+, water and secrete K+ and intercalated cells reabsorb K+, HCO3- and secrete H+
CD travel through the pyramid forming medullary rays of the inner and outer medulla and into the minor calyx
Afferent and Efferent Arterioles
Supply the glomerulus
Afferent - into the glomerulus
Efferent - out of the glomerules
Between afferent & efferent arterioles is the macula densa - Na+ sensing cells of the DCT
Juxta Glomerular Cells
Renin releasing cells located around afferent arteriole as it enters the renal corpuscle
Together with the macula densa cells forms the juxta glomerular apparatus
- controls renal blood flow, glomerular filtration and renin secretion
Hormonal Regulation of Renal Blood Flow
Renin released when there is a reduction in renal blood flow due to:
- decrease blood volume
- fall in systemic pressures
- blockage in renal arteries/arterioles
- reduction in osmolality of tubular fluid reaching JGA
Converts angiotensinogen (from the liver) to Ang I
Ang II is a potent vasopressor
Drugs called ACE (angiotensin converting enzyme) inhibitors prevent the production of Ang II and aldosterone
- are used to lower BP
Glomerular Filtration Membrane
Inner fenestrated capillary endothelium
Supporting mesangium
Middle basement membrane - lamina densa
Outer capillary epithelium contains podocytes
Visceral and parietal layers form the Bowman’s capsule
Filtration
Blood pressure forces 20% fluid (plasma) across membrane:
- Glomerular endothelium
- 60-100 nm -> stops blood cells - Lamina densa (basement membrane)
- thicker than average
- more dense -> stops large plasma proteins - Filtration slits (pedicels of podocytes)
- 3-5 nm -> stops most small proteins
Nephrotic and Nephritic Syndromes
Nephrotic
- proteinuria, hypoalbuminaemia, oedema
- related to degeneration of renal tubular epithelium, glomerular nephritis, diabetic glomerulosclerosis
Nephritic
- haematuria casts, hypertension reduced gfr
- related to acute inflammation
- most are immune complex mediated
Acute and Chronic Renal Failure
ARF - failure over days with increased creatinine and oliguria
CRF - progressive loss of RF over years with sclerotic glomerular damage
Diseases of the Urinary Tract
Immunologic - Ab mediated glomerulonephritis
Metabolic disorders - diabetic nephropathy
Circulatory disturbances - pre renal failure secondary to shock, intrarenal tubular necrosis and CKD glomerulosclerosis
Urinary obstruction - stones, BPH
Bacterial infections
Tumours
