Magnitude of Re-absorption and Secretory Function (Friday 03/11/17)

Question 1

What happens to the filtrate after it enters the Bowman’s capsule?

Answer 1

1. Left untouced by nephron, so amount excreted = amount filtered, like inulin and creatine
2. Filtered then reabsorbed, so amount excreted is less than amount filtered, like glucose, a.a, sodium ions
3. Filtered the secreted, so the amount excreted is more than the amount filteres, like metabolic end products and PAH drug molecules.

Compare plasma concentration of the molecule to the urinary excretion concentration. For (1. left untouched) will have linear line. For inulin the amount excreted = the amount filtered. By comparing a substance’s clearance to that of inulin we can measure GFR.

Question 2

Components of glucose handling

Answer 2

Glucose can be filtered, excreted and reabsorbed, depending on the blood glucose concentration.

Question 3

Components of phosphate handling

Answer 3

Kidney regulates plasma phosphate concentration

High phosphate levels can cause calcification of vasculature, causing disease

Question 4

Components of PAH handling

Question 5

LO’s

Answer 5

• Describe the amount of fluid and solutes filtered and reabsorbed by the kidney per day
• Describe the processes by which different substances may be handled by the kidney (e.g. filtration, secretion, absorption and metabolism)
• Describe the concepts of transport maximum (Tm) and plasma threshold
• Describe the major mechanisms of sodium reabsorption in the nephron