Internal Code: MAS5606
Case Study 1:
Jason had generally been very healthy, however, this appeared to change quite suddenly when he approached his late thirties. He found himself getting sick quite often and noticed that his face became fatter over a relatively short period of time. Clinical tests ordered by his medical doctor revealed that he had high blood glucose. His doctor referred him to a range of specialists and he was eventually informed by his endocrinologist that he had Cushing’s syndrome caused by a pituitary tumour that was autonomously secreting ACTH.
a) State the likely effect on circulating levels of both cortisol and CRH when compared to the healthy condition, and explain the reason for any changes.
b) Explain why Jason’s condition would cause him to get sick often and to have high blood glucose.
c) Which chemical class does cortisol belong to, how does it circulate, and what is its mechanism of action in target cells?
Case Study 2:
Julie was a healthy young adult but trying to diet as she wanted to fit into her new dress for the upcoming dance party. But, unfortunately, she had a weak moment and ate 8 jam doughnuts all at once that she bought from the doughnut van parked near the Agora last Thursday. Within half an hour after ingestion, Julie’s pancreas began increasing its output of insulin.
a) Explain the processes that lead to the pancreas increasing insulin secretion.
b) When Julie was leaving campus (just over an hour after consuming the doughnuts) she got a big fright as she was almost hit by a car that didn’t stop at a pedestrian crossing; it took her quite a while to calm down. What impact do you think this might have on insulin secretion?
Case Study 3:
Patients who are suffering from gastro-oesophageal reflux disease (GORD) usually find that their symptoms are worse after eating fatty meals, and also that they tend to be worse at night.
a) Using your knowledge of the physiological control of gastric motility, explain why eating a fatty meal might increase acid reflux into the oesophagus when compared to a meal high in protein or high in carbohydrate?
b) Why do you think that symptoms of GORD are worse at night?
Case Study 4:
A number of foods are manufactured using additives to reduce calorie content. Two such examples are the sugar alcohol mannitol (which has similar sweetness as sucrose but is very poorly absorbed by the GI system) and the man-made fat molecule Olestra (which has the
same taste and ‘feel’ as dietary fat but is designed such that it cannot be hydrolyzed by lipase). Although useful in the manufacture of ‘diet’ foods, such additives can produce unwanted side-effects.
a) Foods using mannitol as a sweetener (such as sugar-free chewing gum) often have a warning on them which says “Excess consumption may have a laxative effect”. Explain the mechanism by which mannitol might produce such an effect.
b) Although Olestra was initially used by companies with great enthusiasm, by 2010 it had made TIME magazine’s list of “The 50 worst inventions”, due to the discovery that overconsumption caused several unpleasant GI side effects and some significant nutritional deficiencies.
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