Starvation and Metabolic Syndrome

Question 1

What combination of hormones leads to the largest rise in blood glucose?

Answer 1

• glucagon, epinephrine, and cortisol.
  
  • synergistic effect.

Question 2

Main hormonal activators of glycogenolysis:

Answer 2

• norepinephrine and epinephrine.
  
  • glucagon too, but not as strongly.

Question 3

Main hormonal activators of gluconeogenesis:

Answer 3

• cortisol and glucagon.
• norepi/epi do not trigger gluconeogenesis.

Question 4

What hormone stimulates both liver glycogenolysis and gluconeogenesis?

Answer 4

glucagon.

Question 5

The 4 types of hypoglycemia:

Answer 5

1. Insulin induced.
2. Postprandial.
3. Fasting.
4. Alcohol.

Question 6

Treatment for mild and severe insulin induced hypoglycemia:

Answer 6

• mild: oral carbohydrates.
• severe: glucagon shot.

Question 7

Main glucose sources during starvation (time 0 to weeks):

Answer 7

• ingested glucose (4 hours).
• glycogen stores (4-18 hours).
• gluconeogenesis.

Question 8

Once liver glycogen stores are depleted in starvation, what two important changes in body metabolism occur?

Answer 8

1. gluconeogenesis in liver and kidneys increases.
2. fatty acids/ketones become primary metabolic fuel; spares glucose for brain and RBCs.

Question 9

When do ketone bodies become the primary source of metabolic fuel?

Answer 9

14-21 days of starvation.

Question 10

What is the primary ketone body produced during starvation?

Answer 10

• beta-hydroxybutyrate.
  
  • results from NADH and acetyl CoA produced by FA beta-oxidation.

Question 11

Brain fuel source during fed state:

Answer 11

100% glucose.

Question 12

Brain fuel source during starvation state:

Answer 12

• 60% beta-hydroxybutyrate.
• 30% glucose.
• 10% acetoacetate.

Question 13

Metabolic syndrome is defined as meeting three or more of the following criteria (5):

Answer 13

1. central obesity
2. high fasting triglycerides
3. low HDL
4. hypertension
5. hyperglycemia

Question 14

Which two types of fat are insulin sensitive and aid in maintaining/lowering blood glucose?

Answer 14

1. Brown fat.
2. Subcutaneous white fat.

Question 15

Which type of fat is insulin resistant?

Answer 15

visceral white fat.

Question 16

What three things does visceral fat secrete in excess, which promote dyslipidemia, insulin resistance and inflammation?

Answer 16

1. inflammatory markers (C-reactive protein).
2. free fatty acids.
3. adipokines (cytokines).

Question 17

What is hypothesized to be the main cause of T2 diabetes due to visceral fat/metabolic syndrome?

Answer 17

increased FFA secretion from visceral fat.

Question 18

Effects of increased FFA secretion from visceral fat on metabolism:

Answer 18

1. inhibits insulin secretion.
2. decrease glucose uptake in muscle and adipose tissue (insulin activates GLUT4).
3. increase gluconeogenesis (increase glucagon/insulin ratio by lowering insulin).

HYPERGLYCEMIA / T2 DIABETES

Question 19

The three hormones secreted from adipocytes affecting blood glucose (and their classification):

Answer 19

1. Resistin (pro-hyperglycemic).
2. Leptin (anti-hyperglycemic).
3. Adiponectin (anti-hyperglycemic).

Question 20

The main downstream molecule of resistin, leptin, and adiponectin is:

Answer 20

AMPK

Question 21

How does resistin released from adipocytes promote hyperglycemia?

Answer 21

• resistin inhibits AMPK and activates gluconeogenesis.
  
  • AMPK promotes glucose uptake (GLUT4) and glycolysis.

Question 22

How do leptin and adiponectin released from adipocytes promote glucose uptake?

Answer 22

• leptin and adiponectin activate AMPK.
  
  • AMPK promotes glucose uptake (GLUT4) and glycolysis.

Question 23

What changes in adiponectin, leptin, and resistin will cause obesity?

Answer 23

1. adiponectin and leptin deficiency.
2. adiponectin and leptin receptor defects.
3. resistin levels are high.

Question 24

What hormone released from adipocytes interacts with the CNS, and how?

Answer 24

• leptin; reduces food intake and increases energy expenditure via hypothalamus.