Renal Physiology - Physiology MCQ ACEM, Rated A+. GRADED A+

Renal Physiology - Physiology MCQ ACEM, Rated A+. GRADED A+ Which of the following regarding the glomerular filtration rate (GFR) is CORRECT? 1. A fall in systemic blood pressure the glomerular filtration rate falls more than the renal plasma flow 2. Creatinine clearance can be used to measure the glomerular filtration rate 3. 90% of filtrate is reabsorbed by the kidney 4. The GFR is approximately 10L/h 2. Creatinine clearance can be used to measure the glomerular filtration rate The GFR is approximately 125mL/min or 7.5L/h or 180L/day. The normal production of urine a day is 1L. Therefore 99% or more of the filtrate is normally reabsorbed Factors controlling the GFR include: size of the capillary bed, permeability of the capillary bed (50 times that of skeletal muscle), and the hydrostatic and oncotic pressures gradients across the capillary beds CrCl rate is the volume of plasma that is cleared of Cr per unit time and is a useful measure for approximating the GFR, despite the fact that Cr is secreted and reabsorbed by the tubules. Therefore the plasma creatinine clearance can be inaccurate at low levels. The FF = GFR / RPF and is normally 0.16-0.2. When there is a fall in systemic BP, the GFR falls less than the RPF due to the constriction of the efferent arteries What is the action of aldosterone on the kidneys? 1. Promotes sodium and bicarbonate reabsorption 2. Promotes sodium reabsorption and hydrogen secretion 3. Promotes sodium and water reabsorption 4. Promotes sodium reabsorption and potassium secretion 4. Promotes sodium reabsorption and potassium secretion Aldosterone, a mineralcorticoid, promotes Nasup+/sup and water retention, and lower plasma Ksup+/sup concentration by the following mechanisms: 1. Acting on the DCT and CDS, it upregulates and activates the basolateral NKATP. This results in reabsorption of Nasup+/sup and water into blood, and secretion Ksup+/sup into urine 2. Aldosterone upregulates epithelial Nasup+/sup channels increasing apical membrane permeability for Nasup+/sup. Clsup-/sup is reabsorbed in conjunction with Nasup+/sup to maintain the system's electrochemical balance. 3. Aldosterone stimulates secretion of Ksup+/sup into tubular lumen 4. Aldosterone stimulates Nasup+/sup and water reabsorption from the gut, salivary and sweat glands in exchange for Ksup+/sup. 5. Aldosterone stimulates secretion of Hsup+/sup in exchange for Nasup+/sup in the intercalated cells of the cortical collecting tubules regulating plasma bicarb levels and acid/base balance Which of the following hormones does the kidney NOT secrete? 1. Erythropoietin 2. Vitamin D 3. Renin 4. Aldosterone 4. Aldosterone Aldosterone, a mineralocorticoid, produced by the outer section (zona glomerulosa) of the adrenal cortex