30 Questions
What is the primary function of ATP in cellular metabolism?
To serve as the energy currency of the cell
During anaerobic conditions, what is the end product of glycolysis?
Lactate
What is the primary fate of glucogenic amino acids?
Serving as the precursor for the synthesis of glucose
What is the primary energy source utilized by the body during fasting conditions?
Fatty acids from adipose tissue
What is the role of the liver in the integration of metabolism?
Storing energy substrates for later use
What is the primary function of fatty acid oxidation?
Forming acetyl CoA, which enters the TCA cycle
What is the end product of the citric acid cycle?
CO2
Which hormone is responsible for controlling metabolism in various organs of the human body during the fed state?
Insulin
What is the primary function of the hexose monophosphate shunt?
Liberating NADPH
What is the storage form of glucose in the liver and muscle?
Glycogen
What is the common metabolite produced from different fuel sources that enters the citric acid cycle?
Acetyl CoA
What is the mechanism of regulation of enzyme synthesis in metabolic pathways?
Regulation of enzyme synthesis
What is the primary function of the liver in the absorptive state?
Central metabolic clearing house
In the absorptive state, what is the primary source of fuel for the brain?
Glucose
Which tissue has increased fatty acid and triacylglycerol synthesis in the absorptive state?
Liver
What happens to glycogen in the liver during the absorptive state?
It is synthesized from glucose
What is the fate of amino acids in skeletal muscle during the absorptive state?
They are incorporated into proteins
What happens to triacylglycerol in adipose tissue during the absorptive state?
It is inhibited from being degraded
What is the primary source of energy for the brain and muscle during normal conditions?
Glucose
During fasting, which of the following is the primary energy source for the body?
Protein
What is the fate of excess acetyl CoA during fasting?
It is diverted to ketone body formation
Which of the following hormones is decreased during fasting?
Insulin
What is the primary function of hepatic gluconeogenesis during fasting?
To maintain blood glucose levels
During fasting, which of the following is not a primary source of energy for the brain?
Triacylglycerol
In the fasting state, what is the primary source of glucose for the brain?
Gluconeogenesis in the liver
What is the fate of glycerol liberated during lipolysis in adipose tissue during starvation?
It is used for glucose synthesis by the liver
What is the primary fuel used by the skeletal muscle during prolonged fasting?
Fatty acids
What is the role of muscle protein breakdown during starvation?
To provide amino acids for glucose synthesis by the liver
What signals a reduction in protein catabolism during prolonged starvation?
The presence of ketone bodies
What is the primary fate of fatty acids released from adipose tissue during starvation?
They are used as a fuel for various tissues, including the brain
Study Notes
Citric Acid Cycle and Oxidative Phosphorylation
- Acetyl CoA is the common metabolite produced from different fuel sources.
- It enters the citric acid cycle and gets oxidized to CO2.
- Most of the energy is trapped in the form of NADH and FADH2.
- Oxidative phosphorylation: NADH and FADH2 are oxidized in the electron transport chain, generating ATP.
Hexose Monophosphate Shunt
- Concerned with the liberation of NADPH.
- NADPH is utilized for biosynthesis of several compounds, including fatty acids and ribose sugar.
- Ribose sugar is an essential component of nucleotides.
Gluconeogenesis
- Many non-carbohydrate compounds serve as precursors for gluconeogenesis.
- Glucose is synthesized from these precursors.
Glycogen Metabolism
- Glycogen is the storage form of glucose in liver and muscle.
- Glycogen serves as a fuel reserve to meet body needs for a brief period.
Regulation of Metabolic Pathways
- Metabolic pathways are controlled by four mechanisms:
- Availability of substrates
- Covalent modification of enzymes
- Allosteric regulation
- Regulation of enzyme synthesis
Integration of Metabolism during Fed State
- Insulin is the hormone responsible for controlling metabolism in various organs of the body.
- The liver, muscle, and adipose tissue work together to meet the body's metabolic demands.
Carbohydrate, Lipid, and Protein Metabolism during Fasting
- Glucose production and utilization:
- Liver: Glucose production increases through gluconeogenesis.
- Adipose tissue: Glucose uptake and metabolism decrease.
- Skeletal muscle: Glucose uptake and metabolism decrease.
- Brain: Glucose is the primary fuel source.
- Lipid metabolism:
- Adipose tissue: Lipolysis increases, releasing fatty acids (FA) and glycerol.
- Skeletal muscle: FA and ketone bodies are utilized as fuel.
- Liver: FA oxidation increases, and ketone bodies are produced.
- Protein metabolism:
- Skeletal muscle: Muscle proteins are degraded, and amino acids are utilized for glucose synthesis in the liver.
- Liver: Amino acids are utilized for glucose synthesis.
Brain Metabolism during Fasting
- In the early phase of starvation, the brain depends on glucose supplied by liver gluconeogenesis.
- In prolonged starvation, ketone bodies replace glucose as the primary fuel for the brain.
- This reduces protein catabolism.
Integration of Metabolism during Fasting
- The liver, muscle, and adipose tissue work together to meet the body's metabolic demands during fasting.
- The metabolism is reorganized to meet the new demands of fasting.
- Glucose is the fuel of choice for brain and muscle.
- Protein meets the fuel demands of the body.
- Triacylglycerol (TG) of adipose tissue is the predominant energy reserve of the body.
Liver during Fasting
- Carbohydrate metabolism:
- Increased glycogen degradation and gluconeogenesis.
- Complete dependence on hepatic gluconeogenesis from lactate and alanine.
- Lipid metabolism:
- Increased FA oxidation and ketone body formation.
- Ketone bodies meet the fuel demands of the brain.
This quiz covers the roles of the liver, muscle, and adipose tissue in energy substrate metabolism, as well as the integration of metabolism during fed and fasting conditions. Understand how the body regulates energy storage and consumption. Test your knowledge of biochemistry and metabolism!
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
