5) For the subjects in your group plot graphs showing the effects of the various treatments on:
- Rate of urine production (ml/min) versus time. Plot the data for all subjects on the one graph. Make sure you identify each subject
- Urine osmolality versus time. There will be only one subject for this graph.
- Urine Pottasium concentration versus time. There will be 2 (or 3) subjects for this.
- Pottasium excretion rate versus time. This will be for the same 2 (or 3) subjects as above.
• Attach these four graphs to this Worksheet.
Subject: Cheah Yi Ze
Treatment: Control
Subject: Cheah Yi Ze (Male)
Treatment: Control
Subject: Ting Jun (Male)
Treatment: Moderate Exercise
6) What is meant by the term ‘osmolality’?
Osmolality is the concentration of the substances in 1L of water divided by its molecular weight. The units used would be mOsm/kg.
- The average data from all subjects in the entire class (all three days) will be posted on the PHY2021 WebCT site. Use this class data to answer the following:
(a) Describe what happens to the rate of urine production in the 2 different treatment groups.
Based on the results, it can be concluded that the 2 treatment groups tested which were the control and the vigorous exercise displayed different amount in the production of urine. The exercise group showed a lower amount of production in urine as compared to the control(not subjected to any exercise) may be due to blood flow to the kidneys are reduced in order to get greater perfusion to the skeletal muscles. With less blood flowing to the kidneys, the kidneys produce less ultrafiltrate and less urine than a comparably hydrated individual that is not exercising (control subject).
8) Why is there a delay in the onset of the diuresis after water loading in the control subject?
When the subject empties the bladder an hour before the experiment started, this causes the subject to be in a hypertonic state. Then as water intake is consumed by the control subject, the water needs to be reabsorbed and diffuse through the blood stream via the lining of the guts and spread evenly until it reaches the isotonic state. Therefore when excess water is detected, the body would be in a hypotonic state and the plasma osmolarity will decrease. This will result in secretion of ADH to drop and lesser reabsorption of water in the collecting duct.
9) Describe the mechanisms by which severe exercise or emotion could affect the diuresis produced by a water load.
Severe exercise could affect the dieresis produced by a water load as this stimulates the pituitary gland to produce more ADH and this will result in the increase of plasma ADH towards the binding on the V2 receptors. Water is then retained in the body to dilute body fluids.
10) Briefly account for the effects of administered desmopressin on the diuresis (subject B).
Desmopressin affects dieresis by reducing the urine production. Desmopressin will bind to the V2 receptors in the collecting duct to increase water reabsorption. It doesn’t affects the bloodpressure.
11) If a control subject was dehydrated at the beginning of the class, how would you expect this to affect his or her response to the water load?
IF the control subject was dehydrated at the beginning of the class, the effect to his/her response to the water load is that more ADH would be available in the plasma to bind with the vasopressinm receptors, to promote water reabsoption in the collecting tubule. When water is consumed by the subject, the high concentration of ADH causes water to be reabsorbed into the body. Hence the production of urine would be low initially. Gradually the urine production will increase as the baroceptors would detect a change in concentration and therefore suppresses the hypothalamus. This decreases the production of ADH and decreases the permeability of the collecting tubule causing less water to be reabsorbed.
12) What effect does alcohol have on water diuresis? (You might like to think about your own personal experience!) What is the mechanism of action of alcohol on water diuresis?
The effects of alcohol is that it increases water dieresis as symptoms such as thirst and mild dehydration will be accounted for after consumption of alcohol. This is because alcohol will bind to the osmoreceptors in the hypothalamus which suppresses the firing rate of impulses by the osmoreceptors. Then, less ADH would be produced and thus lesser ADH would be able to bind with the vasopressin receptors which decreases the tubular permeability to water in the collecting duct. Water would not be retained in the body and thus secreted.
13) Fill in the following table.