2002 - Question 1

An emotionally-diisturbed patient in a mental health care Institution is found to be water per day, well in excess of a normal intake of 1.0 to 1.5 litres. Outline the likely physiological responses to this excess water intake. Include in y (i) effects of the extra water intake on fluid compartments in the body; (ii) how the changes in fluid balance are sensed; (iii) subsequent homeostatic responses to restore more nomal fluld balance.


2002 - Question 2


For a person giving a 500 mi blood donation:

(i) Indicate the immediate effect of the 500 ml blood loss on blood pressure and explain why this occurs,

(ii) Explain the physiological mechanisms by which the body compensates for the blood loss in the initial few minutes,

(iii) Why are blood donors encouraged to lie dovvn while giving blood and for a few min afterwards? Explain..


2003 - 1. Jim Smith is a healthy 25-year-old male. He is aware of health issues, exercises regularly, and starts each day by drinking 2 litres of pure water to “cleanse his system". He consumes the water over a 15-minute period. Discuss fluid distribution in Jim as he consumes the water and explain how systems in Jim’s body will act to retum the fluid distribution to normal.
[10 min]


2004 - Question 1.
A television cameraman working in Africa consumes some untreated, contaminated water and contracts cholera. He has to travel for several hours in a convoy with no medical help and during this time has had severe diarrhoea for 5 hours. When the convoy reaches a medical facility he is disoriented and looks pale and unwell with a dry tongue and reduced skin turgor. His film crew say that his diarrhoea must have involved the loss of many litres of fluid. He has not been urinating and has only taken a few sips of water.
a) Briefly outline reasons for the extensive fluid loss in diarrhoea in cholera. Where does the fluid come from and how are the body's main fluid compartments affected?
(12 marks)
b) Would you expect the man's plasma osmolality to be high, low or normal when he reaches the medical centre? Explain briefly.
(3 marks)
c) Why has the man produced little urine during the 3 or 4 hours before reaching the medical centre? Explain 2 main mechanisms limiting urine production.
(10 marks


2005 - Question 1.
Discuss the processes that occur in the kidney to determine the concentration of glucose in urine. In your answer explain how glucose moves through relevant membranes and what drives its movement. Explain why glucose is undetectable in normal urine but present in substantial concentrations in the urine of a diabetic patient with a blood glucose of 17 mmol/L.
(13 marks)


2006 - Question 2.
A 20 year old woman with food poisoning, who has been vomiting repeatedly over 3 hours, is examined at a hospital emergency department. Her blood pressure is found to be 110/70 lying and 80/55 standing. Blood gases on an arterial blood sample give the following values.
Reference Range
PO2 90 mmHg (80-100)
PCO2 47 mmHg (35-45)
AHCO3 41 mmol/L (21-28)
pH 7.56 (7.35 – 7.45)
(a) The fluid lost in vomiting is typically hypotonic. Indicate how this loss would be expected to affect the composition of fluid compartments in the body.
(5 marks)
(b) Discuss the “blood gas” values, indicating how vomiting could have led to the values observed.
(5 marks)
(c) Explain why this woman’s blood pressure falls when changing from a supine to upright position?
(8 marks)
(d) How would you expect her glomerular filtration rate (GFR) to compare with normal? Indicate the most important influence on GFR in this situation.
(3 marks)


2007 - Question 3
Rotaviruses are a common cause of diarrhoea in infants. Mechanisms by which rotaviruses lead to diarrhoea are thought to include
• inhibition of intestinal disaccharidases so that disaccharides such as sucrose are not converted to
monosaccharides like glucose, for absorption.
• inhibition of Na+-cotransporters for uptake from the intestine of glucose and some amino acids.
• net secretion of Na+ and Cl- from intestinal villi into the intestinal lumen.
(a) Explain why these effects would lead to diarrhoea.
(5 marks)
(b) Discuss possible effects of rotavirus-induced diarrhoea on body fluid compartments, indicating any assumptions you make about the nature of fluid lost into the intestinal lumen; any forces that drive movement of water or ions from one compartment to another; and how the nature of barriers between compartments is relevant to fluid movement.
(6 marks)


2008 - Question 1.
A healthy70kg adult male starts an evening run normally hydrated and on the warm summer evening, loses 700ml of sweat while running 13km. Sweat is a hypotonic fluid containing mainly water, Na+ and Cl -.
a) Describe the immediate effect of such a fluid loss on the main fluid compartments of the body.
(4 marks)
b) Describe mechanisms of the likely homeostatic response(s) in the body to the water loss in this man.
(10 marks)