Laboratory Report

Activity:

Influence of Fluid Intake on Urine Formation

Date:

current date

Predictions

Materials and Methods

  1. Subjects were asked to refrain from alcohol and caffeine for a day before the start of the experiment. Explain why this is important.
  2. What technique was used to measure urine and plasma osmolarity?

Results

Urine Production Rate
Subject Normal Dehydrated Water Loaded
30 min (mL) L/day 30 min (mL) L/day 30 min (mL) L/day
1

Minimum 3 characters, two numbers, one digital full stop. The RV(L) value is valid, thank you. Sorry. Your value is wrong. Please try again. The valid RV(L) value is correct, thank you.

2
3
Average

Minimum 3 characters, two numbers, one digital full stop. The RV(L) value is valid, thank you. Sorry. Your value is wrong. Please try again. The valid RV(L) value is correct, thank you.

Average Daily Urine Production Under Different Hydration States
  1. Does dehydration increase, decrease, or not change average urine production rate (L/day).
  2. Does water loading increase, decrease, or not affect average urine production rate (L/day).
Osmolarity (mosm/L)
Subject Urine Plasma
Normal Dehydrated Water Loaded Normal Dehydrated Water Loaded
1
2
3
Average

Minimum 3 characters, two numbers, one digital full stop. The RV(L) value is valid, thank you. Sorry. Your value is wrong. Please try again. The valid RV(L) value is correct, thank you.

Minimum 3 characters, two numbers, one digital full stop. The RV(L) value is valid, thank you. Sorry. Your value is wrong. Please try again. The valid RV(L) value is correct, thank you.

Blood Plasma and Urine Osmolarity Under Different Hydration States
  1. Does dehydration increase, decrease, or not change average urine osmolarity (mosm/L)?
  2. Does water loading increase, decrease, or not change average urine osmolarity (mosm/L)?
  3. Does dehydration increase, decrease, or not change average plasma osmolarity (mosm/L)?
  4. Does water loading increase, decrease, or not change average plasma osmolarity (mosm/L)?

Discussion

  1. State whether dehydration results in production of a concentrated or dilute urine.
  2. State whether water loading results in production of concentrated or dilute urine.
  3. Describe how ADH secretion during dehydration changes urine production and osmolarity.
  4. Describe how ADH secretion during water loading changes urine production and osmolarity.
  5. Describe how ADH secretion maintains plasma osmolarity levels during dehydration and water loading.
  6. Explain why in this experiment you did not see significant changes in plasma osmolarity during dehydration or water loading.
  7. Discuss why maintaining plasma osmolarity within normal limits is important.
  8. Restate your predictions that were correct and give the data from your experiment that supports them. Restate your predictions that were not correct and correct them, giving the data from your experiment that supports the correction.

Application

  1. Drinking alcoholic or caffeinated beverages increases urine output more than drinking an equivalent amount of water.

    1. How do you think these beverages affect ADH secretion?
    2. Would urine osmolarity be increased or decreased?
  2. Explain why someone with diabetes insipidus must drink more water than normal.
  3. Explain what happens to plasma osmolarity when you give a severely dehydrated person large amounts of pure water.
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