BIOCHEM 3H03 Lecture Notes - Lecture 9: Proximal Tubule, Sodium-Potassium Alloy, Ureter
5 Feb 2017
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Regulate acid-base balance: h+ and bicarbonate (hco3. Excrete metabolic products and foreign substances: urea (protein breakdown), uric acid, (nucleic acids), creatinine (from muscle creatine), hemoglobin breakdown products, hormone metabolites, etc, removal of drugs, pesticides, food additives, anything made water soluble can be excreted. Produce and secrete hormones and enzymes: 1,25-dihydroxyvitamin d- active form of vitamin d, erthyropoietin-peptide hormone involved in erythrocyte production from bone marrow, renin recall raa system. Blood enters through renal artery (~ 25% of cardiac output), leaves via renal vein. Urine is collected in the renal pelvis and travels down the ureter to the bladder. Urine is an ultra filtrate of plasma: filtrate contains water and low molecular weight solutes, all cells and most proteins are retained by the filter. Composition of the urine is changed before excretion: water is removed, some solutes are re-absorbed, some substances are secreted into the urine things not reabsorbed or produced in the tubules. Don"t filter (cid:894)or re-absorb) what is needed.
