Kidney and Urinary tract Flashcards
What are the functions of the kidney?
- Elimination - metabolic waster, drugs and toxins
- Homeostasis - electrolytes, water, pH, blood pressure (renin), bone metabolism, bone marrow
Describe the kidney gross anatomy
- the two kidneys are located in the posterior wall of the abdomen at the level of the 11th and 12th ribs and are wrapped by a protective layer of fat
- the kidney can be divided into the renal cortex (outer region) and the medulla (inner region). The renal columns are connective tissue extensions that radiate downward from the cortex through the medulla to separate the most characteristic features of the medulla, the renal pyramids and renal papillae.
- The papillae are bundles of collecting ducts that transport urine made by the nephrons to the calyces of the kidney for excretion. The pyramids and renal columns taken together constitute the kidney lobes
What is the glomeruli?
- nephrons are the “functional units” of the kidney; they cleanse the blood and balance the constituents of the circulation
- the afferent arterioles form high pressure capillaries called the glomeruli. The rest of the nephron consists of a tubule whose proximal end surrounds the glomerulus - this is Bowman’s capsule.
- the glomerulus and Bowman’s capsule together form the renal corpuscle.
- These glomerular capillaries filter the blood based on particle size.
- After passing through the renal corpuscle, the capillaries form a second arteriole, the efferent arteriole.
Describe filtration of the bowman’s capsule
- one layer of the bowman’s capsule is composed of uniquely shaped cells (podocytes) with extending finger-like arms to cover the glomerular capillaries. These projections interdigitate to form filtration slits, leaving small gaps between the digits to form a sieve. As blood passes through the glomerulus the plasma filters between these sieve-like fingers to be captured by bowman’s capsule
- overall filtration is regulated by fenestrations in capillary endothelial cells, podocytes with filtration slits and the basement membrane between capillary cells.
Describe the structure of the nephron
- after leaving the renal corpuscle, the filtrate passes through the renal tubule in the following order: proximal convoluted tubule (found in the renal cortex), loop of Henle (mostly in medulla), distal convoluted tubule (found in the renal cortex), collecting tubule (in the medulla) then the collecting duct (in the medulla).
Describe acute kidney injury
- Pre-renal: shock, dehydration, hemorrhage, often related to the heart and the low cardiac output
- Renal: inflammation, infection, ischemia, drugs and toxins
- Post-renal: acute urinary tract obstruction
-> acute kidney failure - acute onset of symptoms, if treated early enough the damage is not permanent
Describe chronic kidney injury
- Pre-renal: hypertension, diabetes
- Renal: primary glomerulopathies, chronic tubulointerstitial diseases
- Post-renal: chronic urinary tract obstruction
- often asymptomatic at first slowly progressive and irrerversible damage, loss of glomeruli, chronic inflammation, scarring.
What are the consequences of kidney injury?
- loss of water regulation - edema, often exacerbated by protein loss in the urine
- electrolyte disturbances - minerals lost, Na+, K+, Ca2+, PO4
- lower blood pH - acidosis
- increased waste products
- anemia - due to loss of vitamin D
- lower bone density - due to loss of vitamin D
- management of chronic renal failure: 1. medication, 2. dialysis, 3. transplant
Describe primary and secondary glomerular diseases
- Primary glomerulopathy: affect kidney primarily or exclusively
- Secondary glomerulopathy: systemic diseases affect multiple organs e.g. diabetes, systemic lupus, vasculitis
-> glomeruli diseases are associated with several complications
* immune mechanisms underlie most types of primary glomerular diseases and many of the secondary glomerular diseases (e.g. poststreptococcal glomerulopathy). The deposition of circulating immune complexes in the glomerulus initiates complement and/or Fc receptor mediated leukocyte activation resulting in glomerular injury.
What are the different investigations for renal diseases?
- urinalysis: hematuria (blood in urine), proteinuria (protein in urine)
- blood: increased creatinine and urea (impaired waste elimination)
- kidney biopsy: needed for definitive diagnosis. use light microscopy, immunofluorescence and electron microscopy.
What are tubular diseases?
Acute tubular necrosis (ATN): acute tubular injury (ATI/ATN) is a clinicopathologic entity characterized by damage to tubular epithelial cells and an acute decline in renal function *ATN is potentially reversible
- Ischemic injury: low cardiac output (heart failure), low blood volume (hemorrhage), vasodilation (sepsis, anaphylaxis)
- Nephrotoxic injury: exogenous (drugs, toxins), endogenous (muscle injury, transfusion reaction).
Describe kidney cyst
Cystic diseases of the kidney are a heterogenous group comprising hereditary, developmental, and acquired disorders.
- Acquired: simple, end-stage failure
- Genetic: polycystic kidney disease
- Neoplastic: renal carcinoma variant
- Developmental: congenital syndromes
What is the pathogenesis of kidney cysts?
Altered growth and differentiation of tubular epithelium
Describe acquired simple cysts
simple cysts are generally innocuous lesions that occur as multiple or single cystic spaces of variable size. Simple cysts are a common postmortem finding that has no clinical significance.
Describe adult polycystic kidney disease
Acquired cystic kidney disease: occurs in patients with end-stage renal disease who have undergone dialysis for many years. Multiple cysts may be present in both the cortex and the medulla and may bleed, causing hematuria.
