Hormonal Control/Signaling

00:01 So in summary what we have seen over the past couple of pathways are as follows.

00:04 Epinephrine, glucagon binding stimulates the phosphorylation of all glycogen enzymes.

00:11 The phosphorylation of the glycogen breakdown enzymes like glycogen phosphorylase will activated favoring glycogen breakdown.

00:19 Phosphorylation of the glycogen synthesis enzyme, glycogen synthase, inactivates it.

00:23 Epinephrine also activates glycogen breakdown and glucose production.

00:29 Now if you think about that, that makes sense if the AM is putting glucose out.

00:34 Glucose production comes from gluconeogenesis and glycogen breakdown produces glucose so that it can be exported from cells.

00:42 These two events are coordinated so that the body has the glucose that it needs.

00:48 Epinephrine inactivates glycogen synthesis and that makes sense; because the glucose that you are producing, you don't wanna waste in a futile cycle.

00:56 On the opposite site, insulin stimulates phosphoprotein phosphatase. So when insulin is present, blood glucose is high and the body is wanting to deal with it.

01:07 This stimulates the removal of phosphates from all the proteins that we have talked about before.

01:12 That's going to reverse all of those effects. Glycogen breakdown enzymes become less active meaning that they are not breaking down glycogen anymore.

01:20 And the glycogen synthase becomes active so it's gonna grab that glucose that's coming in and deal with it.

01:27 So cells start making glycogen instead of breaking it down.

01:31 And cells will also start breaking it down in glycolysis instead of making it in gluconeogenesis.

01:38 So epinephrine and glucagon are stimulated in the production of glucose.

01:42 Whereas insulin is stimulating the use of that glucose in the synthesis of glycogen.