Fasting and Starvation Metabolism

Questions and Answers

What syndrome is commonly associated with starvation, particularly in children under 1 year of age?

Kwashiorkor

Beriberi

Marasmus (correct)

Anemia

In marasmus, which component does muscle primarily provide to the liver?

Fatty acids

Glucose

Amino acids (correct)

Ketone bodies

What is the primary function of fatty acyl-CoA in the context of starvation?

Production of insulin

Ketogenesis (correct)

Formation of glycogen

Synthesis of glucose

Which metabolic processes are primarily utilized by the brain during starvation?

Metabolism of glucose and ketone bodies Signup and view all the answers

What can lead to marasmus in adults?

Diseases that prevent swallowing Signup and view all the answers

What occurs during hepatic gluconeogenesis in response to fasting?

Increased triglyceride degradation in adipose tissue Signup and view all the answers

What is the relationship between hepatic gluconeogenesis and the urea cycle?

The synthesis of glucose from alanine is linked to the urea cycle Signup and view all the answers

What happens to acetyl-CoA during starvation?

Its concentration increases, leading to ketone body formation Signup and view all the answers

What role does oxaloacetate play in Starvation metabolism?

It is required to combine with acetyl-CoA to form citrate Signup and view all the answers

What is the primary source of glucose during prolonged fasting?

Breakdown of protein in muscle tissue Signup and view all the answers

What process occurs simultaneously with lipolysis in adipose tissue during fasting?

Protein degradation in muscle Signup and view all the answers

Which of the following best explains the increase in ketone bodies during starvation?

Increased concentration of acetyl-CoA Signup and view all the answers

What is the fate of fatty acids during the fasting state?

They undergo beta-oxidation to form acetyl-CoA Signup and view all the answers

Study Notes

Fasting and Starvation Metabolism

Hepatic gluconeogenesis relies on protein degradation from muscle and triglyceride breakdown from adipose tissue.
Glucose synthesis from alanine in the liver is linked to the urea cycle, which is crucial in maintaining nitrogen balance.
Hepatic ketogenesis utilizes fatty acids derived from triglyceride degradation, leading to ketone body formation.

Starvation Process

Fatty acids are broken down via β-oxidation, yielding acetyl-CoA which enters the tricarboxylic acid (TCA) cycle for oxidative metabolism into CO2.
The presence of oxaloacetate is necessary for acetyl-CoA entry into the TCA cycle; during starvation, gluconeogenesis reduces oxaloacetate availability.
Increased acetyl-CoA levels during starvation promote the production of ketone bodies instead of continuing through the TCA cycle.

Marasmus Syndrome

Marasmus is a severe form of malnutrition prevalent in children under 1 year in developing countries, but can affect all age groups.
In marasmus, the body mobilizes fat as an energy source for ketogenesis while muscle-derived amino acids support gluconeogenesis in the liver.
The brain utilizes both glucose and ketone bodies as energy sources during this state of malnutrition.
Prolonged starvation exhausts energy and protein reserves, potentially leading to death from starvation.
Adults may experience marasmus due to diseases affecting swallowing or food access, such as throat or esophageal cancer, dementia, or stroke.

Description

This quiz explores the metabolic processes involved in fasting and starvation. Focused on hepatic gluconeogenesis, ketogenesis, and the implications towards marasmus syndrome, it emphasizes the biochemical pathways and their significance in energy production and nutrient balance. Test your understanding of how the body adapts during periods of nutrient deprivation.