Lab 5: renal function lab Flashcards
What is specific gravity?
This is a measure of the weight of particles in compared to that of distilled water (specific gravity of 1.000)
What is the normal specific gravity for urine?
1.002 and 1.035
A specific gravity above ______ indicates de-hydration
1.020
What are the mechanisms in the kidney to concentrate urine?
The countercurrent mechanism in the juxtamedullary loop of Henle and neighbouring vasa recta creates a hyper osmotic gradient. The hyper osmotic gradient in the medulla facilitates water leaving the collecting duct, for reabsorption into the blood when aquaporins are present
How long before diuresis begins for protocol B water (hypotonic)?
20 mins (very large after 40 mins) This depends on whether you are hydrated of hyper hydrated
What happens when we are dehydrated?
There is an increase in the ECF osmolarity which is detected by the hypothalamic osmoreceptors. There is an increase in the activity in the paraventricular and supraoptic nuclei to release ADH. This binds to the V2 receptor on the collecting duct cells and AQP2 goes to the membrane and then there is an increase in the absorption of water to decrease urine output
What happens when there is an intake of a hypotonic fluid (like water) in controlB?
There is a decrease in the ECF osmolarity which is detected by the hypothalamic osmoreceptors. There is an decrease in the activity in the paraventricular and supraoptic nuclei to stop the release of ADH. There is no binding to the V2 receptor on the collecting duct cells and AQP2 doesn’t go to the membrane and then there is a decrease in the absorption of water to increase urine output
What happened to the rate of urine production for the water + exercise subjects (compared to with water only subjects)?
It was delayed but increased at 40 mins
Why was there a difference in the way the body handled the water when the subject exercised?
Exercise means that there is an increase in sympathetic activity which leads to renal vasoconstriction so there is decreased renal blood flow and GFR and urine production. There is also an increase in the release of ADH. Both of these lead to delayed diuresis
What happened to the rate of urine production for subjects consuming the sports drink?
it was delayed and then increased a lot
Why is diuresis delayed when you drink the sports drink?
The intake of the isotonic drink means that there is no change in the ECF osmolarity, so there is no mechanisms to initiate diuresis. Glucose is detected in the blood but he β cells, insulin is released, glucose goes into the muscle, liver and fat cells, ECF osmolarity then decreases so ADH decreases and urine output increases
Where is glucose reabsorbed?
proximal straight and proximal convoluted tubule
Where is glucose reabsorbed?
proximal straight and proximal convoluted tubule
What happens when we intake isotonic NaCl solution?
There is very delayed diuresis
The fluid enters the ECF which is the same osmolarity as the ICF so there is no net movement into the cells.
The ECF volume has increased which means that the plasma volume has increased
ANP released to decrease aldosterone release from the adrenal glands and decrease ADH release, it also reduces the activity of Na+/K+ ATPase
What is the result of a water deprivation test on a person who is normal, a person with CDI and a person with NDI?
- normal: same plasma Na+ osmolarity, increase urine osmolarity
- CDI: increased plasma Na+ osmolarity, decrease urine osmolarity
- NDI: increased plasma Na+ osmolarity, decrease urine osmolarity
