Glycogen and glucose homeostasis

Why this matters

Your blood contains about four and a half grams of glucose — roughly a sugar cube — and your brain consumes far more than that every hour. Everything in this lesson exists to bridge that gap. It is also the lesson that prepares you for the commonest metabolic emergency in a dental chair, where knowing the right amount of the right sugar, and when NOT to put anything in someone's mouth, is the difference between a manageable event and a catastrophe.

The big picture

Blood glucose is held in a narrow band by two opposing hormones acting on one organ. Insulin says store; glucagon says release. The liver obeys both, first by making and breaking glycogen, then — when that runs out — by building glucose from scratch. Muscle stores glycogen too, but selfishly: it cannot give any back.

The 14 cards in this lesson

1. 01Four grams, and a brain that eats it
2. 02Building glycogen needs a primer
3. 03Breakdown that pays a dividend
4. 04One switch, two opposite effects
5. 05Liver glycogen is public, muscle glycogen is private
6. 06Making glucose from scratch
7. 07How a beta cell measures glucose
8. 08Two hormones, one liver
9. 09What happens as the hours pass
10. 10Diabetes: two different diseases
11. 11Clinical alert — in the lesson
12. 12Clinical alert — in the lesson
13. 13Diabetes and the periodontium
14. 14Clinical alert — in the lesson

You have got it when

You are ready to continue when you can explain why glycogen breakdown saves an ATP, why muscle glycogen cannot raise your blood sugar, and exactly what you would do for a shaky, sweating diabetic patient mid-appointment.