Nutrition Lecture 7.2: Glucagon

What secretes glucagon?

Alpha cells of islets of Langerhans (Pancreas)

Is glucagon a counterregulatory hormone?

Yes

What is the main function of glucagon?

Prevent hypoglycemia

What are the stimuli of glucagon?

1. Low blood glucose (Primary)

2. Amino acids

3. Epinephrine

What is glucagon secretion inhibited by?

1. Increased blood glucose

2. Insulin

What does glucagon initiate in the liver to increase blood glucose?

1. Glycogenolysis

2. Gluconeogenesis

How do glucagon affect fatty acids?

Hepatic oxidation

How do glucagon affect amino acids?

Increased uptake by liver

Does glucagon increase or decrease ketogenesis?

Increase

What are the steps of glucagon mechanisms?

1. Bind to receptor on hepatocyte

2. Adenylyl cyclase activated

3. cAMP levels increased

4. Protein kinases activated

5. Cascade of carbohydrate and lipid metabolism

What are blood glucose levels in Hypoglycemia?

Less than 40 mg/dl

How is Hypoglycemia resolved?

Glucose ingestion

Why is Hypoglycemia considered a medical emergency?

CNS needs blood glucose

What are the most important hormone changes that prevent Hypoglycemia?

1. Glucagon

2. Epinephrine

What are the symptoms of Hypoglycemia?

1. Adrenergic

2. Neuroglycopenia

What mediates the release of glucoregulatory hormones?

Hypothalamus

How strongly does cortisol stimulate glycogenolysis and gluconeogenesis?

Glycogenolysis - None

Gluconeogenesis - Moderate

How strongly does epinephrine stimulate glycogenolysis and gluconeogenesis?

Glycogenolysis - Strong

Gluconeogenesis - None

How strongly does glucagon stimulate glycogenolysis and gluconeogenesis?

Glycogenolysis - Moderate

Gluconeogenesis - Moderate

What are the types of hypoglycemia?

1. Insulin induced

2. Postprandial

3. Fasting

What is Insulin-induced hypoglycemia caused by?

Injecting too much insulin

What is Insulin-induced hypoglycemia treated with?

Eating carbohydrates

What is Postprandial hypoglycemia caused by?

Too much insulin released after meal

What is Postprandial hypoglycemia treated with?

Eating smaller meals

Which patients are usually seen with fasting hypoglycemia?

1. Hepatocellular damage

2. Alcoholics

What is fasting hypoglycemia caused by?

1. Liver cannot produce glucose levels after fasting

2. Beta cell tumor

What is inhibited during alcohol intoxication?

Gluconeogenesis

What does Disulfiram inhibit?

Aldehyde dehydrogenase

What is Disulfiram used for?

Alcoholism

Which individuals can alcohol cause dangerous hypoglycemia in?

1. Prolonged exercise

2. Fasting

3. Diabetes