Metabolism and Energy Balance — Chapter 22

I. Appetite and Satiety

• What part of the brain controls food intake?

  • What are the two centers in the hypothalamus that control food intake?

    • How does the feeding center behave?

• The hypothalamus

  • The feeding center and the satiety center

    • It is tonically active

• What happens when the feeding center is destroyed?

  • What does the satiety center do?

    • What happens when the satiety center is destroyed?

• Feeding stops

  • It inhibits the feeding center

    • Overeating is induced

II. Fed-State Metabolism

A. Carbohydrates

• What happens to glucose during the fed state?

  • What are the two possible fates of glucose that stays in circulation?

• About 30% is taken up by the liver, while 70% stays in circulation

  • It can be used for ATP production or stored

What is glycogenesis?

• How can excess glucose be stored besides glycogen?

The process of storing glucose as glycogen

• As triglycerides through lipogenesis

Where is glycogen stored mainly?

• How much of a glucose supply does liver glycogen provide?

In the liver and skeletal muscle

• About four hours of supply

B. Proteins

• What are two possible fates of amino acids during the fed state?

  • What happens to excess amino acids during the fed state?

• Protein production and fat production

  • They are stored as fat

C. Fats

• Where are triglycerides stored?

What are two uses of cholesterol?

• In the liver and adipose tissue

Steroid hormone synthesis and membrane components

III. Fasted-State Metabolism

A. Carbohydrates

• What happens to glycogen during the fasted state?

  • What is glycogenolysis?

    • What is gluconeogenesis?

• It is broken down through glycogenolysis

  • The breakdown of glycogen

    • The production of glucose

B. Proteins

• Which amino acids are used first during the fasted state?

  • What digests proteins during the fasted state?

    • What does deamination produce?

• Free amino acids

  • Proteases digest proteins

    • Ammonia, which is converted to urea by the liver

• What happens to deaminated amino acids during ATP production?

How can deaminated amino acids contribute to glucose production?

• They enter the respiration pathway

In the liver, they enter a reverse glycolysis pathway to produce glucose

C. Fats

• What is lipolysis?

  • Where does glycerol enter energy metabolism?

How do fatty acids enter energy metabolism?

• The breakdown of triglycerides by lipases

  • Glycerol feeds into glycolysis

They undergo beta-oxidation before entering the Krebs cycle

IV. Control of Metabolism

A. Insulin and Glucagon

• Which organ produces insulin and glucagon?

  • Which pancreatic cells produce insulin?

    • Which pancreatic cells produce glucagon?

• The pancreas

  • Beta cells

    • Alpha cells

• Which hormone is dominant during the fed state?

  • A What stimulates insulin?

What does insulin promote?

• Insulin

  • A high glucose concentration in the blood

Glycogen synthesis and lipid synthesis

• Which hormone is dominant during the fasted state?

  • What stimulates glucagon?

What does glucagon promote?

• Glucagon

  • A low glucose concentration in the blood

Glycogen metabolism and glucose synthesis