Renal Disease Flashcards
What is the function of the kidney?
o Excretion waste products e.g. creatinine, urea, metabolites of xenobiotics (chemical constituents foreign to animal life – drugs, plants, food additives, industrial chemicals, & environment pollutants)
oMaintain water balance.
oMaintain Blood Pressure water & Na retention/excretion.
oMaintain cardiac function K excretion.
oMaintenance of pH excretes H+.
What is a nephron?
microscopic structural & functional unit of kidney (1-1.5 million/kidney)
What are the parts of the nephron?
Renal corpuscle glomerulus & Bowman’s capsule Renal tubule epithelial cells with lumen
Describe the Bowman’s Capsule
2 layers – parietal layer simple squamous epithelium & visceral layer podocytes (highly specialized cells that wrap around capillaries) -Filtrate enters Bowman’s capsule for transportation along renal tubules.
What is the glomerulus?
o Capillary tuft – filters blood - surrounded by Bowman’s capsule.
o Diameter of the afferent arteriole > diameter of the efferent arteriole – induces pressure – force some molecules with small molecular weight into ultrafiltrate.
o Albumin too large to be filtered – low albumin conc. In urine – sign of glomerular damage.
What are the 3 stages of excretion in the nephron?
1st Glomerular Filtration remove solutes from blood (water, salts, area, uric acid, glucose, amino acids) 180 L/day (140 ml/minute)
2nd Tubular Reabsorption water & most nutrients (all glucose, amino acids, most Na & Cl) via active & passive transport
3rd Tubular Secretion waste products resecreted.
What is the glomerular filtrate?
ultrafiltrate similar to plasma (without most proteins).
Describe the adrenal glands.
Endocrine glands – messenger system – feedback loops of hormones – released by internal glands into circulatory system – regulate distant target organs.
What are the functions of the adrenal glands?
o Osteogenesis/ossification – synthesise Vitamin D – needed for Ca absorption.
o Erythropoiesis - erythropoietin (EPO) synthesis – commits haematopoietic stem cells to differentiate to make RBC.
o Salt/water balance via aldosterone synthesis(mineralocorticoid) – Na+ absorbed & K+ excreted – hyperkalaemia (renal disease)
o Regulate body’s stress – cortisol(glucocorticoid) & adrenaline (glucocorticoid)
o Corticosteroids – stress response, immune response, regulation of inflammation, CHO metabolism, protein catabolism, blood electrolyte levels, behavior.
How does the adrenal gland regulate electrolyte balance and blood volume?
o Antidiuretic Hormone (ADH)/Vasopressin/Arginine Vasopressin (AVP) – secreted from posterior pituitary– insert aquaporin channels at collecting ducts – control water reabsorption.
o Aldosterone – exchange of Na+ and K+
o Hypovolaemia – stimulates ADH & aldosterone production – RAAS activation.
What does RAAS stand for
Renin-Angiotensin-Aldosterone System
Explain RAAS
o Hormone system – regulate blood pressure, electrolyte balance, & systemic vascular resistenace
o Hypovolaemia- juxtaglomerular cells in kidneys convert prorenin into renin - secreted into bloodstream.
o Renin converts angiotensinogen (from liver) to angiotensin I (decapeptide)
o Angiotensin converting enzymes (ACE) (found on surface of vascular endothelial cells e.g. lungs) – convert angiotensin I to angiotensin II (octapeptide)
o Angiotensin II binds to hypothalamus – stimulate thirst, increasing water intake – stimulate release of ADH
o Angiotensin II stimulate aldosterone secretion from adrenal glands (increase Na reabsorption, increase k excretion)
o Blood pressure increases
What is nephropathy?
renal disease
What is nephritis/nephritic syndrome?
Inflammatory kidney disease
What is nephrosis/nephrotic syndrome?
non-inflammatory kidney disease?
What is end stage kidney disease?
kidney failure
Pre-renal causes of renal disease?
o Reduced blood flow (severe blood/fluid loss, dehydration, vomit, diarrhoea, congestive heart failure, cardiovascular disease, abnormalities, ineffective endocarditis)
o Haemolytic anaemia – porphorin pigment in haemoglobin – toxic to kidneys
o Hypertension
o Liver disease
o Diabetes Mellitus – too much sugar – toxic – damage vessel walls
What are renal causes of kidney disease?
o Damage to renal tissue (glomerular basement membrane & tubules)
o Tubular damage toxin exposure/ingestion
o Autoimmune disease
o Hereditary e.g. polycystic hormone disease
What are post-renal causes of renal disease?
obstruction to urine outflow – urolithiasis, metastatic carcinomas, UTIs (cystitis (lower urinary tract-bladder) & pyelonephritis (upper urinary tract-kidney))
What is Acute Renal Disease/Acute Kidney Injury (ARD/AKI)?
temporary failure of kidney (hours/days)
What is chronic renal disease?
progressive, irreversible destruction of kidney – dialysis & treatment
What are the lab findings that indicate renal disease?
hyperkalaemia, hypocalcaemia, normocytic normochromic anaemia, metabolic acidosis, proteinuria (chronic renal disease), rising serum urea (waste product – protein & liver breakdown) & creatinine (waste product – muscle metabolism)
Signs & symptoms of kidney disease?
Nausea, vomiting, anorexia, fatigue & lethargy, insomnia, oedema, puritis, high blood pressure, SOB (increase H+ ions)
Complications of renal disease?
Metabolic acidosis, hyperkalaemia, heart disease, oedema, anaemia, bone weakness
How does renal disease cause bone weakness?
o Calcitriol activated Vit. D – 1st hydroxylation occurs in liver – 2nd hydroxylation occurs in kidneys
o Synthesis of cholecalciferol (Vit. D3) – lower layers of the epidermis through photochemical reactions with UV-B
o Ergocalciferol (Vit D2) ingested.
o Calcitriol – increase intestinal absorption of Ca (Mg, PO4)
o Low Vit D. – hypocalcaemia – compensatory increase in PTH (hyperparathyroidism) – increase serum calcium via increased intestinal & renal absorption, osteoclast activity
How does renal disease cause oedema?
build up of fluid in body – tissue becomes swollen.
oProteinuria & renal disease – loss of albumin (maintains colloid osmotic pressure/oncotic pressure)
oWater moves out of blood into intestinal fluid to maintain osmolality.
oImpaired ability to excrete water.
How does renal disease cause anaemia?
Erythropoietin synthesized in adrenal glands – anoxia & hypoxia stimulate EPO function – decreased RBC – normocytic normochromic anaemia
How does renal disease cause
How does renal disease cause heart disease?
oReduced glomerular filtration – excess fluid – cause hypertension – damage arteries – coronary artery disease.
oHyperkalaemia causes muscle weakness, cardiac arrhythmia, cardiac arrest.
oHeart disease – leading cause of death for dialysis patients
How does renal disease cause hyperkalaemia?
oaldosterone levels decreased (mineralocorticoid deficiency CKD) – K+ not excreted.
oK+ essential for maintaining resting potential & generating action potential.
oVentricular fibrillation – arrhythmia
How does renal disease cause metabolic acidosis?
oImpaired excretion of H+
oSOB – hyperventilation – decrease CO2 – increase plasma pH to treat acidosis – bicarbonate buffer system (homeostatic pH balance)
oCO2 + H2O ⇌ H2CO3 ⇌ H+ + HCO3-
oLe Chatelier
oCarbonic anhydrase catalyse the conversion of CO2 to H2CO3
Pathogenesis of renal disease (DM)?
Diabetes mellitus – poor management – hyperglycaemia – thickening & scarring of nephron – angiopathy of glomerular capillaries – nephrotic syndrome, proteinuria – causes dialysis.
Risk factors of renal disease?
Smoking, diet, obesity, genetic factors, family history, abnormal kidney structure, certain medications, high BP, older age, uncontrolled DM
Treatment of renal disease?
Dialysis, transplantation, diet (low, protein, fat, cholesterol)
Diagnosis of renal disease?
> Test of Tubular Function
Test of Glomerular Function
oSerum urea – nitrogenous end product of protein & AA catabolism – urease assay – AA & proteins deminated in liver – ammonia is liberated (urease) – ammonia measured via Nesseler’s or Bertelot Reaction
oSerum creatinine – muscle & protein metabolism - modified Jaffe procedure – formed in liver & pancreas - transported to liver cells – creatine kinase phosphorylates creatine to form creatine phosphate (muscle energy source) – creatinine waste product
oProteinuria
oInsulin/creatinine clearance test – determine glomerular filtration rate – 24 hour urine collection – ideal marker = insulin – freely filtered & not reabsorbed, or secreted in the tubules
oEstimated GMR – Crockcroft-Gault & Modification of Diet in Renal Disease (MDRD) equations – age, gender, race, weight, serum creatinine
