Adipose Tissue Quiz

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Questions and Answers

What is the primary location for the synthesis of ketone bodies in the body?

Brain

Kidneys

Muscles

Liver (correct)

During long periods of starvation, which fuel source can the brain start to utilize?

Ketone bodies (correct)

Fatty acids

Lactate

Glucose exclusively

In what condition does uncontrolled diabetes most likely lead to ketosis?

Insufficient insulin leading to increased lipolysis (correct)

High glucose levels without insulin deficiency

Excess insulin production

Decreased fatty acid oxidation

What is the role of glucagon during starvation in relation to ketogenesis?

Stimulates ketogenesis Signup and view all the answers

Which statement best describes the fate of ketone bodies in the body?

They can be utilized by extrahepatic tissues like the heart and muscles. Signup and view all the answers

What biochemical pathway does enhanced gluconeogenesis interfere with during starvation?

Krebs cycle by utilizing oxaloacetate Signup and view all the answers

Which resource is primarily utilized by red blood cells (RBCs) for energy?

Glucose Signup and view all the answers

What is the significance of having a high glucagon to insulin ratio?

It is ketogenic and stimulates ketogenesis. Signup and view all the answers

What is the consequence of increased lipolysis due to insulin deficiency?

Increased ketone body production Signup and view all the answers

Hyperemesis during pregnancy can lead to which metabolic condition?

Ketosis Signup and view all the answers

What is the primary function of white adipose tissue?

Energy storage Signup and view all the answers

Which statement best describes the mitochondria presence in brown adipose tissue?

Numerous mitochondria contributing to its brown color Signup and view all the answers

What key protein is involved in the thermogenesis process?

Thermogenin Signup and view all the answers

During fasting, what process allows for the release of fatty acids into the blood?

Lipolysis Signup and view all the answers

What is notably absent in the process of thermogenesis in the absence of uncoupling proteins?

ATP production Signup and view all the answers

Which of the following statements about brown adipose tissue is NOT true?

It contains fewer mitochondria compared to white adipose tissue. Signup and view all the answers

How does brown adipose tissue primarily generate heat?

By uncoupling oxidation from phosphorylation Signup and view all the answers

What is the primary storage form of energy in white adipose tissue?

Triglycerides Signup and view all the answers

How many ATP are generated from 8 acetyl-CoA in the old ATP calculation system?

96 ATP Signup and view all the answers

What is the main regulatory molecule that inhibits CAT1 during fatty acid synthesis?

Malonyl-CoA Signup and view all the answers

What is the net ATP yield from the complete oxidation of a fatty acid with 14 carbons using the new calculation system?

92 ATP Signup and view all the answers

During which condition is beta oxidation promoted due to increased free fatty acids in tissues?

Fasting Signup and view all the answers

Which biological process is primarily inhibited when ATP levels are high?

Beta oxidation Signup and view all the answers

What is the initial product formed during the rate-limiting step of beta oxidation?

Fatty acyl carnitine Signup and view all the answers

Which hormone is primarily responsible for promoting fatty acid synthesis during the fed state?

Insulin Signup and view all the answers

What is the effect of glucagon on fatty acid metabolism during starvation?

Stimulates beta oxidation Signup and view all the answers

What is the overall total ATP gain from beta oxidation and the citric acid cycle for the complete oxidation of a fatty acid in the old system, assuming 18 carbons?

131 ATP Signup and view all the answers

Study Notes

Adipose Tissue Types

White Adipose Tissue (WAT)
- Primarily functions in energy storage.
- Contains minimal mitochondria.
- Composed of 80% triglycerides (TAG), which require significant water for oxidation.
Brown Adipose Tissue (BAT)
- Engaged in thermogenesis, uncoupling oxidation from phosphorylation.
- Abundant mitochondria and cytochromes contribute to its brown color.
- Critical for newborns and hibernating animals.

Thermogenesis

Heat is generated by uncoupling oxidation from the phosphorylation process, releasing energy as heat rather than as ATP.
Occurs via uncoupling protein (thermogenin).

Lipolysis

Mobilization of stored fats during fasting results in fatty acids (FAs) appearing in the blood.
Each turn of β-oxidation yields:
- Old system: 5 ATP (or 7 cycles resulting in 35 ATP).
- New system: 4 ATP (or 7 cycles leading to 28 ATP).
Each Acetyl-CoA entering the citric acid cycle produces 12 ATP, leading to a total potential gain of 131 ATP in the old system.
Example: Complete oxidation of an 18-carbon fatty acid using the new system results in significant ATP production.

Importance of β-Oxidation

Serves as an energy source during fasting.
Provides Acetyl-CoA for synthesizing crucial compounds like cholesterol.

Regulation of β-Oxidation

Feeding Status:
- Fasting promotes lipolysis and increases free fatty acids (FFA) in tissues, stimulating β-oxidation.
- Carbohydrate intake leads to higher insulin levels, inhibiting lipolysis and reducing β-oxidation.
Rate-limiting step involves forming fatty acyl carnitine (catalyzed by CAT1), inhibited by malonyl CoA during the fed state.
In starving conditions, the decreased malonyl CoA leads to increased β-oxidation.

Energy Needs of Cells

High ATP levels reduce respiratory chain activity, leading to elevated FADH2 and NADH levels, inhibiting dehydrogenases of β-oxidation.
Conversely, low ATP levels stimulate β-oxidation as NADH and FAD are oxidized.

Ketogenesis and Ketolysis

Ketone bodies formed in the liver are utilized in extrahepatic tissues, providing alternative fuel sources for heart muscles and during prolonged fasting.
RBCs primarily utilize glucose, while the brain usually relies on glucose but can adapt to ketone bodies during starvation.

Ketosis

Arises from uncontrolled diabetes (DM) or prolonged starvation, causing a lipolytic response and an increase in ketone bodies due to excess Acetyl-CoA.
Enhanced gluconeogenesis limits acetyl CoA's entry into TCA, resulting in ketone body production.

Management of Ketoacidosis

Initial treatment includes administering fluids and insulin to lower blood sugar levels and stabilize the patient.

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Description

This quiz covers key concepts related to white and brown adipose tissue, focusing on their functions and characteristics. You'll learn about energy storage, thermogenesis, and the biochemical components involved. Test your knowledge and deepen your understanding of these vital tissues.