Describe the physiological consequences that follow an intravenous bolus of 50mls of
50% glucose.
This question was mainly about the metabolic consequences of an intravenous load of 25 grams of glucose. For a good pass the main areas that required description included:
Additional marks were awarded for details of where these actions of insulin occurred and the enzymes that were stimulated or inhibited by insulin.
Some candidates stated that this bolus of hypertonic glucose would produce a significant and prolonged increase in plasma osmolarity and then went on to produce detailed descriptions of the thirst and ADH mechanisms. In fact with a normal insulin response glucose is rapidly cleared from the blood.
Reference Text: Guyton Chp 67
Gerich, John E. "Physiology of glucose homeostasis." Diabetes, Obesity and Metabolism 2.6 (2000): 345-350.
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Regittnig, Werner, et al. "Assessment of transcapillary glucose exchange in human skeletal muscle and adipose tissue." American Journal of Physiology-Endocrinology and Metabolism 285.2 (2003): E241-E251.
Balentine, Jerry R., et al. "Effect of 50 milliliters of 50% dextrose in water administration on the blood sugar of euglycemic volunteers." Academic emergency medicine 5.7 (1998): 691-694.