2006B16 Describe the physiological consequences of acute hypoglycaemia.



·         Intro and importance

·         Metabolic pathways and key enzymes

·         Physiological response to ↓BGL

·         Clinical signs of ↓BGL


Intro and importance:

·         Blood glucose level tightly controlled, normally 3-7mM

·         Hypoglyaemia <3mM. Symptoms and signs concealed by anaesthesia.

·         Brain, RBC are reliant on glucose (brain can adapt to ketones but slowly)

·         Severe hypoglycaemia can be fatal


Metabolic pathways and key enzymes:

Glycolysis (GL)

·  Hexokinase

Gluconeogenesis (GNG)

·  From pyruvate, lactate, fructose, amino acids, glycerol

·  Note glucose 6 phosphatase mainly expressed in liver > renal cortex

Glycogenolysis (GGL)

·  Glycogen phosphorylase

Glycogenesis (GG)

·  Glycogen synthase

Lipolysis (LL)

·  Hormone-sensitive lipase

De novo lipogenesis (DNL)

·  Lipoprotein lipase, acetyl-CoA carboxylase, fatty acid synthase

Ketogenesis (KG)

·  Acetyl-CoA thiolase


Physiological effects of hypoglycaemia:


·  ↓Insulin and ↑glucagon

·  ↑Cortisol (anterior pituitary -> adrenal cortex)

·  ↑Growth hormone (anterior pituitary)

·  ↑Catecholamines (adrenal medulla)


·  ↑GNG, ↓GL

·  ↑GGL, ↓GG

·  ↑LL, ↓DNL

Skeletal muscle

·  ↓GL

·  ↑GGL, ↓GGL

·  No direct GNG (lacks glucose 6 phosphatase)

·  ↑Proteolysis -> hepatic GNG via Cori cycle and glucose-alanine cycle



·  ↓Glucose uptake for glycerol

·  ↑LL, ↓DNL


Clinical signs:

Of hypoglycaemia

·  Weakness, hunger, agitation

·  Confusion, coma, death

Of sympathetic hyperactivity

·  CVS: ↑HR (β1), ↑BP (CO: β1, TPR: α1)

·  Musculoskeletal: tremor (β2)

·  Skin: sweating (mAChR), pallor (α1)

·  Eyes: pupil dilatation (α1)



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