GLUCAGONPresented By Daniel Vakili

Familiar Analogy

Familiar Analogy

GlucagonGlucagon Receptor

Target Tissue with stored glucose

Glucose

Structure

>29 amino acid polypeptide hormone

>nonsteroid

Where does it come from?>Synthesized and secreted from alpha cells in the islets of langerhans in the pancreas.

> Cleaved from proglucagon

Action

>Raise Blood Sugar

- Glycogenolysis

- Gluconeogenesis

>Target tissues

- Liver, Muscle, Fat

>Glucagon and Insulin are part of a feedback system that keep blood sugar at normal levels

ReceptorG-Protein Coupled Receptor

> Part of the GPCR Family

>Heptahelical

> Extracellular region binds to ligands

> Intracellular region interacts with multi-subunit G-Protein

Receptor

> Ligand activates

> GDP-GTP

> alpha subunit dissociates

cAMP: a secondary messengercyclic adenosine monophosphate

Glucagon-Receptor > G-proteins dissociate > α subunit-adenylate cyclase > cAMP > removes inhibitory subunit of PKA

Normal Blood Values

Insulin and Glucagon normally keep plasma glucose

>below 170mg/dl after a meal (absorptive state)

>above 50mg/dl between meals(postabsorptive state)

Too Little Glucagon: Hypoglycemia

> Symptoms: tremor, hunger, weakness, weakness, blurred vision, and mental confusion.

Too Much Glucagon:

>Glucagonoma- tumor of alpha cells resulting in overproduction

> Hyperglycemia

> Ketoacidosis - fatty acids to Ketone bodies

> Gluconeogenesis - Weight loss, anemia, ketoacidosis, diabetes mellitus.

Conclusion

Glucagon is a hormone antagonist to insulin, signaling the release of glucose from storage into the blood through glycogenolysis and gluconeogenesis.

Important for maintaining homeostasis.