Physiology Flashcards
What is the gold standard for calculating GFR
Inulin clearance
Does Creatinine clearance over or under estimate GFR? why?
Overestimates b/c it is freely filtered by glomerulus but also secreted by proximal tubule
Where does most electrolyte re-absorption occur?
proximal tubule
Where do loop diuretics act?
Thick ascending loop of Henle
Where do thiazides act
Distal tubule
What are the features of SIADH?
- Hyponatremia
- low serum osmolality, high urine osmolality
- normal BUN/Cr
- low serum uric acid
What happens if you correct low sodium too quickly?
Central Pontine Myelinolysis
How is renin mediated? What does it do
1) macula densa senses decreased Na in blood,
2) hypo perfusion of kidney,
3) afferent arteriole resistance (decrease GFR)
4) sympathetic stimulation
Converts Angiotensinogen to Angiotensin I
What does Angiotensin Converting Enzyme do?
Converts Angiotensin I to Angiotensin II
Degrades bradykinin leading to vasoconstriction
Where does Aldosterone come from? How is it released? What does it do?
- Adrenal gland - Glomerulus
- Stimulated by ATII
- Increases re-absorption of Na-Cl in collecting duct, acidifies urine, excretes K in distal tubule
What happens in RTA II
Defect in reabsorption of bicarb in proximal tubule leading to hyperchloremic metabolic acidosis (acidosis self limiting)
What happens in RTA I
- Distal tubule unable to secrete H ions
- hypercloremic metabolic acidosis leads to increase in increased urinary calcium -> nephrocalcinosis
What is the calculation for anion gap? What is normal range?
Na - (Cl + HCO3)
8 - 14
What are some examples of causes of anion gap acidosis?
MUDPILES
Methanol Uremia Diabetic/starvation ketoacidosis Paraldehyde Isoniazid/iron Lactic acid Ethylene glycol Salicylates
What are some examples of causes of non anion gap acidosis?
HARDUP
Hyperalimentation Acetazolimide RTA/Renal insufficiency Diarrhea Ureteroenterostomy Pancreatic fistula
Why does secondary hyperparathyroidism occur in ESRD? What is treatment?
Impaired calcium re-absorption in distal tubule, Increased phosphatemia, lack of conversion to active form of Vital D (1-25) leading to decrease small bowel absorption of calcium;
Treatment is calcitonin
What can occur if gadolinium is administered to an ESRD patient?
nephrogenic systemic fibrosis
What are some signs of IgA nephropathy?
- recurrent acute gross hematuria after URI or exercise,
- young adults(2nd-3rd decade),
- mesangial deposits IgA
What are some signs of post streptococcal Acute glomerulonephritis
- latent hematuria
- previous strep
- pyoderma.
- anti-streptolysin O positive
- low serum complement C3/C4
What regulates erythropoietin
hypoxia -> up regulation of hypoxia inducible factor 1 alpha (HIFa)
where does PTH act?
distal tubule
What is the first to be impacted in unilateral urinary obstruction?
Water absorption d/t defect in aquaporin channels
What scenarios impact sex hormone binding globulin?
liver dysfunction
obesity (decrease)
nephrotic syndrome
what impact does glucose have on sodium?
pseudohyponatremia: for every 100 drops by 1.6
