Kidney Flashcards
(20 cards)
Determinants of GFR and influence on urine formation
NFP is sum of hydrostatic and colloid osmotic forces that either favor or oppose filtration
Hydrostatic pressure inside glomerular capillaries -> promotes filtration
Colloid osmotic pressure of proteins in Bowman’s capsule -> promotes filtration (0)
Hydrostatic pressure in Bowman’s capsule outside capillaries -> opposes filtration
Colloid osmotic pressure of glomerular capillary plasma proteins -> opposes filtration
SNS -> vasoconstriction -> decrease GFR
Hormones and autacoids -> renin-Angiotensin-aldosterone system -> increase GFR
Normal GFR
125ml/min = 180 liters a day
80-180mmhg provides constant GFR
PCT components
Reabsorption: NaCl, glucose, K+, AAs, proteins, urea, water
Secretion:
H+, foreign substances, organic anions, organic cations
LOH
Countercurrent mechanisms
Descending loop
Water reabsorption
NaCl diffuses out
Ascending
Na+ reabsorbed (active)
Water stays in
DCT
Reabsorption
NaCl,
water (ADH),
HCO3
Secretion K+ Urea H+ NH3 Some drugs
Collecting tubule
Resorption
Water (ADH)
Reabsorption or secretion Na K H- NH3
Formation of dilute urine
Continue electrolyte reabsorption
Decrease water reabsorption
Mechanism: decreased ADH rel;ease and reduced water permeability in distal and collecting tubules
Decrease plasma osmolarity -> decrease ADH -> decrease water reabsorption
Formation of concentrated urine
Continue electrolytes reabsorption
Increase water reabsorption
Mechanism:
Increased ADH release which increases water permeability in distal and collecting tubules
High osmolarity in renal medulla
Countercurrent flow of tubular fluid - expends energy to create a concentration gradient
Increase plasma osmolarity -> decrease ADH -> decrease water reabsorption
Diabetic nephropathy
Early manifestation: microalbuminuria
Albumin excretion range: >30 mg/day, <300 mg/day
G6PD deficiency
X-linked recessive, more males affected
Cause - decreased G6PD deficiency -> oxidative hemolysis injury -> hemolysis
Reduced glutathione (GSH) required to neutralize compounds such as H2O2
Pathogenesis: 2 to 3 days after expose -> hemolysis
GSH -> oxidants attack of Hb -> Hb denatures and precipitates -> Heinz bodies -> intravascular hemolysis
Clinical features:
Intravascular hemolysis
Other cells with less damage -> extravascular hemolysis
Lymphoid progenitors vs myeloid progenitor
Lymphoid - NK, B, T
Myeloid - neutrophil, monocytes, eosinophil, basophils, platelets, erythrocyte
Nephrotic syndrome
Pathophysiology: excessive glomerular permeability to plasma proteins
Clinical manifestations: massive proteinuria, hypoalbuminemia, hyperlipidemia and lipiduria, generalized edema ( due to low serum albumin/low oncotic pressure)
Increased renal Na retention by of uncontrolled activation of epithelial Na channels
Complications: Infections and sepsis Thrombosis AKI ESRD if heavy proteinuria not going into remission
Nephrons in each kidney and blood flow it receives
Each human kidney has 1 million nephrons
Blood flow:
about 22% CO or 1100ml/min
about 650 ml of plasma
Total body iron
Functional:
Hemoglobin
Myoglobin
Enzymes
Strange
Ferritin
Hemosiderin
Vitamin B12 Deficiency Cause and pathogen
Required for recycling TH4 -> reversed with folate Thymidine
Causes: pernicious anemia
Autoimmune gastritis -> decrease production of intrinsic factor -> pernicious anemia
Pathogenesis:
Achlorhydria (in elderly) impairs vit B12 release from R binders
Gastrectomy causes loss of intrinsic factor
Ileal resection or diffuse ileal disease
Malabsorption syndromes - increased requirements (pregnancy, hyperthyroidism)
Vit B12 clinical features
Nonspecific - easily fatiguability, severe cases dysnpea and CHF
Ineffective erythropoiesis -> mild jaundice
Megaloblastic changes -> beefy red tounge
Increased risk for development of gastric carcinoma
Neurological lesions: symmetrical numbness tingling, burning of feet or hands -> unsteadiness of gait and loss of position sense
Will fail to resolve with vit B12
B12 metabolism
- Haptocorrin frees VitB12 from pepsin in stomach
- Pancreatic processes release B12 from haptocorrin in duodenum and B12 binds to IF
- IF transported to ileum where it is endocytosed by ileal enterocytes that express receptor for IF (cubilin)
- B12 associates with transcobalamin II (carrier protein) and is secreted into plasma
- Transcobalamin II delivers B12 to other cells of body such as bone marrow and GI tract
Define anemia and useful red cell indices
Reduction of oxygen-transporting capacity of blood, resulting from a decrease in the red cell mass to subnormal levels
Red cell indices:
Mean cell volume: average volume of RBC in fluid
Mean cell hemoglobin: average mass of Hb/RBC in picograms
Mean cell hemoglobin concentration: average concentration of Hg in a given volume of packed red cells in g/dL
Chronic polynephritis
Definition: chronic tubulointersitial inflammation and scarring involving the calyces and pelvis, important Cause of CKD
Cause: Reflux nephropathy (most common) -> results from superimposition of a UTI on congenital Vesicoureteral reflux and intrarenal reflux
Clinical features:
Gradual onset of renal insuffiency
HT and asymmetrically contracted kidney
Bilateral diseases -> hyposthenuria manifested by polyuria and nocturia
Urine formation
- Filtration - non selective, 20% of renal plasma flow (Bowman’s capsule)
- Reabsorption - highly variable and selective, most electrolytes and nutritional substances completely reabsorbed
- Secretion - highly variable, important for rapidly excreting waste products, foreign substances and toxins
- Excretion
Glucose is not excreted - 50% reabsorbed 50% filtration
Creatinine - 0 reabsorption
Sodium and water - evenly filtrate and reabsorbed - little is excreted (more sodium excretion then water)
