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Water diuresis

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Introduction

1) What does the word 'diuresis' refer to? Diuresis refers to the increase in urine flow that are caused by diuretics which in turn causes higher urine release. 2) What are the particular characteristics of a 'water diuresis'? Water dieresis is the excretion of urine after drinking water; results from reduced secretion of the antidiuretic hormone of the neurohypophysis in response to the lowered osmotic pressure of the blood.When there is an increase in water uptake, hence the plasma osmolarity increases. The osmoreceptors in the anterior hypothalamus would then be suppressed and causes less ADH to be secreted from the posterior pituitary gland. This decreases the water permeability of the distal tubule and collecting duct causing lower water absorption. Besides that, the urine osmolarity would also decrease to a value lower than 30mOsm/kg H2O and there will be an increase in urine which is diluted. 3) In the table below record the details for each of the subjects in your group. If there were only 3 subjects in your group draw a line through the last row (Subject D). Subject Treatment Sex Body Weight (kg) Volume of Water Ingested (litres) A Control ( Richard ) M 70.5 0.546 B Vigorous exercise ( Ting Jun) M 63.0 0.756 C N/A N/A N/A N/A D N/A N/A N/A N/A Calculation: Volume of water ingested = body weight � 12mL = 70.5�12mL = 846ml=0.846L 4) ...read more.

Middle

60 20 20 20 20 20 Urine volume (ml) 200 110 200 290 160 30 Urine flow (ml/min) 3.30 5.50 10.00 14.50 8.00 1.50 Na+conc'n (mmol/litre) - - - - - - Na+ excretion rate (?mol/min) - - - - - - K+conc'n (mmol/litre) (Mg/L X dilution factor) / Mr 19.1 18.98 6.45 3.94 6.91 24.35 K+ excretion rate (?mol/min) (K+conc X Urine Flow) 63.03 104.39 64.50 57.13 55.28 36.53 Cl-conc'n (mmol/litre) 2.0 1.0 1.0 2.4 0.7 9.5 Cl-excretion rate (?mol/min) 6.60 5.50 10.00 34.80 5.60 14.25 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. 7) 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. ...read more.

Conclusion

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. Stimulus Type/Site of Receptors ADH Response Physiological response on Urine Volume Physiological response on Blood Volume Increased osmolality (dehydration) Increased osmolality (dehydration) Osmoreceptors Increase ADH production to promote water uptake by binding on type 2 vasopressin receptors Decreases Decreased osmolality Decreased osmolality Osmoreceptors Decrease ADH production to inhibit water retention Increases Increased blood volume Increased blood volume Baroreceptors Decrease production of ADH, inhibit water retention Increases Decreased blood volume Decreased blood volume Baroreceptors Increase production of ADH, promote water uptake by binding on type 2 vasopressin receptors Decreases ?? ?? ?? ?? 2 ...read more.

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