Physio/ganong

Front 1

List 4 factors that stimulate potassium secretion by the cortical collecting ducts.

Back 1

1. aldosterone
2. increased plasma K+ conc.
3. increased flow rate in cortical collecting tubules
4. alkalosis
A diuretic that inhibits aldosterone, decreased plasma K+ conc, acute acidosis and low Na+ intake would all tend to decrease K+ secretion by cortical collecting tubules.

Front 2

Aldosterone tends to shift K+ from ECF into the cells. TRUE/FALSE

Back 2

TRUE.

Front 3

A reduction in plasma protein concentration to 3.6g/dl would increase the capillary filtration rate, raising interstitial fluid volume and interstitial fluid hydroststic pressure. TRUE/FALSE

Back 3

TRUE.

Front 4

If a patient has a urine osmolarity of 80mOsm/L, could this signify diabetes insipidus?

Back 4

Yes. This osmolarity would be maintained despite overnight water restriction.
When H2O restriction is applied, the high urine flow rate leads to rapid depletion of ECF volume and severe hyponatremia.
Even primary aldosteronism or a renin secreting tumor would still not lead to an inability to concentrate urine.

Front 5

Lasix inhibits the Na+-2Cl-K+ cotransporter in the ascending limb of the loop of Henle. TRUE/FALSE

Back 5

TRUE. This causes marked natriuresis and diuresis, but also reduces the urine concentrating ability.
It also increases K+ excretion.

Front 6

What is the result of excessive secretion of renin?

Back 6

This will lead to large amounts of angiotensin 11, which will cause marked constriction of efferent arterioles. This will reduce renal blood flow, increases glomerular hydrostatic pressure, and decreases peritubular capillary hydrostatic pressure.

Front 7

Does high urine flow occur in type 1 diabetes?

Back 7

Yes. This is true because the filtered load of glucose exceeds the renal threshold, resulting in an increase in glucose concentration in the tubule, which decreases the osmotic driving force for H2O absorption.

Front 8

List three loop diuretics.

Back 8

1. Furosemide
2. Ethacrynic acid
3. Bumetanide

Front 9

What is a side effect of a loop diuretic?

Back 9

Hypokalemia. This is caused by the inhibition of Na+-2Cl-K+ co transport in the loop of Henle and by the increased tubular flow rate in the cortical collecting tubules, which stimulate potassium secretion.

Front 10

App. 80-90% of HCO3 reabsorption occurs in the proximal tubule under normal conditions as well as in acidosis. TRUE/FALSE

Back 10

TRUE. For each HCO3 ion reabsorbed, there must also be a hydrogen ion secreted.

Front 11

Thiazide diuretics inhibit NaCl co-transport in the luminal membrane of the early distal tubules. TRUE/FALSE

Back 11

TRUE.

Front 12

How is Phosphate excretion controlled by the kidneys?

Back 12

It is controlled via an overflow mechanism. When the transport maximum for reabsorbing phosphate is exceeded, the remaining phosphate in the renal tubules is excreted in the urine and can be used to buffer H= and form titratable acid.
PO4 starts to spiull into urine when the concentration of ECF rises above a threshold of 0.8mmol/L, which is usually exceeded.

Front 13

A reduction in the number of functional nephrons to 25% of normal would cause a compensatory increase in GFR and urine flow rate of the surviving nephrons and decreased urine concentrating ability. TRUE/FALSE

Back 13

TRUE.

Front 14

With excessive secretion of ADH there is a marked increase in water permeability in the late distal tubules and collecting ducts, resulting in water retention, volume expansion and decreased sodium and protein conc in the ECF. TRUE/FALSE

Back 14

TRUE. As volume expansion occurs and as blood pressure increases, there is an "escape" from volume retention, so that urine flow rates return to normal.

Front 15

Does the proximal tubule normally absorb app. 65% of the filtered water.

Back 15

Yes. Smaller percentages are reabsorbed in the descending loop of Henle and in the distal and collecting tubules. The ascending limb of Henle is relatively impermeable to water and therefore reabsorbs very little water.