Textbook Question
Define glycogenesis, glycogenolysis, gluconeogenesis, and lipogenesis. What is (are) likely to be occurring:
a. Shortly after a carbohydrate-rich meal
b. Just before waking up in the morning?
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Ch. 24 Nutrition, Metabolism, and Energy Balance
Marieb, Hoehn11th EditionHuman Anatomy & PhysiologyISBN: 9780136874034
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Table of contents
- Ch. 1 The Human Body: An Orientation24
- Ch. 2 Chemistry Comes Alive25
- Ch. 3 Cells: The Living Units21
- Ch. 4 Tissue: The Living Fabric20
- Ch. 5 The Integumentary System11
- Ch. 6 Bones and Skeletal Tissues19
- Ch. 7 The Skeleton14
- Ch. 8 Joints7
- Ch. 9 Muscles and Muscle Tissue26
- Ch. 10 The Muscular System26
- Ch. 11 Fundamentals of the Nervous System and Nervous Tissue19
- Ch. 12 The Central Nervous System26
- Ch. 13 The Peripheral Nervous System and Reflex Activity32
- Ch. 14 The Autonomic Nervous System19
- Ch. 15 The Special Senses26
- Ch. 16 The Endocrine System23
- Ch. 17 Blood25
- Ch. 18 The Cardiovascular System: The Heart24
- Ch. 19 The Cardiovascular System: Blood Vessels27
- Ch. 20 The Lymphatic System and Lymphoid Organs and Tissues14
- Ch. 21 The Immune System: Innate and Adaptive Body Defenses27
- Ch. 22 The Respiratory System21
- Ch. 23 The Digestive System31
- Ch. 24 Nutrition, Metabolism, and Energy Balance26
- Ch. 25 The Urinary System26
- Ch. 26 Fluid, Electrolyte, and Acid-Base Balance24
- Ch. 27 The Reproductive System24
- Ch. 28 Pregnancy and Human Development25
- Ch. 29 Heredity11
Marieb, Hoehn11th EditionHuman Anatomy & PhysiologyISBN: 9780136874034Not the one you use?Change textbook
Chapter 24, Problem 13
A person has been on a hunger strike for seven days. Compared to normal, he has:
a. Increased release of fatty acids from adipose tissue and ketosis
b. Elevated glucose concentration in the blood
c. Increased plasma insulin concentration
d. Increased glycogen synthase (enzyme) activity in the liver.
Verified step by step guidance1
Step 1: Understand the physiological response to prolonged fasting. During a hunger strike, the body shifts from using glucose as its primary energy source to utilizing stored fat and protein. This process is known as the metabolic adaptation to fasting.
Step 2: Analyze the role of adipose tissue during fasting. Fatty acids are released from adipose tissue through lipolysis, which is stimulated by hormones like glucagon and epinephrine. These fatty acids are then used for energy production, and ketone bodies are formed in the liver as a byproduct of fatty acid metabolism (ketosis).
Step 3: Examine blood glucose levels during fasting. After several days of fasting, blood glucose levels typically decrease because glycogen stores in the liver are depleted. The body relies on gluconeogenesis (the production of glucose from non-carbohydrate sources) to maintain minimal blood glucose levels.
Step 4: Evaluate plasma insulin concentration during fasting. Insulin levels decrease during fasting because there is less glucose available in the bloodstream, reducing the need for insulin to facilitate glucose uptake by cells.
Step 5: Assess glycogen synthase activity in the liver. Glycogen synthase is an enzyme responsible for glycogen synthesis, which is active when insulin levels are high and glucose is abundant. During fasting, glycogen synthase activity decreases because glycogen stores are depleted and the body is not synthesizing glycogen.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Metabolic Adaptation to Fasting
During fasting, the body undergoes metabolic adaptations to maintain energy homeostasis. Initially, glycogen stores are utilized for energy, but after a few days, the body shifts to using fatty acids and ketones as primary energy sources. This shift helps preserve muscle mass and provides a more efficient energy source during prolonged periods without food.
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Ketosis
Ketosis is a metabolic state that occurs when the body has limited access to glucose, prompting it to break down fatty acids into ketone bodies for energy. This process is particularly significant during prolonged fasting or carbohydrate restriction, as it allows the brain and other tissues to utilize ketones, thus sparing glucose for essential functions.
Hormonal Regulation During Fasting
Fasting triggers hormonal changes that regulate metabolism. Insulin levels decrease, promoting lipolysis (fat breakdown) and inhibiting glycogen synthesis. Conversely, glucagon levels rise, stimulating the release of glucose from glycogen stores and enhancing ketogenesis in the liver, which is crucial for energy supply during extended periods without food.
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Related Practice
Textbook Question
Which of the following yields the greatest caloric value per gram?
a. Fats
b. Proteins
c. Carbohydrates
d. All are equal in caloric value.
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Textbook Question
Body temperature regulation is:
a. Influenced by temperature receptors in the skin
b. Influenced by the temperature of the blood perfusing the heat regulation centers of the brain
c. Subject to both neural and hormonal control
d. All of the above.
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Textbook Question
Describe the site, major events, and outcomes of glycolysis.
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Textbook Question
What is cellular respiration? What is the common role of FAD and NAD⁺ in cellular respiration?
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Textbook Question
Transamination is a chemical process by which:
a. Protein is synthesized
b. An amine group is transferred from an amino acid to a keto acid
c. An amine group is split from the amino acid
d. Amino acids are broken down for energy
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