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Questions and Answers
What physiological change occurs in the kidneys during starvation?
What physiological change occurs in the kidneys during starvation?
Which hormone's level is likely to increase in response to prolonged starvation affecting the kidneys?
Which hormone's level is likely to increase in response to prolonged starvation affecting the kidneys?
How does total starvation impact kidney function over an extended period?
How does total starvation impact kidney function over an extended period?
What is one of the primary roles of the kidneys during periods of starvation?
What is one of the primary roles of the kidneys during periods of starvation?
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Which of the following statements about the kidneys' response to starvation is accurate?
Which of the following statements about the kidneys' response to starvation is accurate?
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What primary energy source do resting skeletal muscles utilize during fasting?
What primary energy source do resting skeletal muscles utilize during fasting?
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In a fasting state, what is the primary source of energy for the brain?
In a fasting state, what is the primary source of energy for the brain?
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Which enzyme is activated in the liver during a fasting state to promote glycogen breakdown?
Which enzyme is activated in the liver during a fasting state to promote glycogen breakdown?
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Which of the following is NOT inactivated during a fasting state in the liver?
Which of the following is NOT inactivated during a fasting state in the liver?
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What is the primary energy source for adipose tissue in a fasting state?
What is the primary energy source for adipose tissue in a fasting state?
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Which enzyme's activity is induced in the liver during the well-fed state?
Which enzyme's activity is induced in the liver during the well-fed state?
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What role does insulin play in the liver during the well-fed state?
What role does insulin play in the liver during the well-fed state?
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Which of the following processes is activated by insulin in the liver during the well-fed state?
Which of the following processes is activated by insulin in the liver during the well-fed state?
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What metabolic process is primarily responsible for the creation of glucose from non-carbohydrates during starvation?
What metabolic process is primarily responsible for the creation of glucose from non-carbohydrates during starvation?
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Which of the following processes decreases in the liver during starvation?
Which of the following processes decreases in the liver during starvation?
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What happens to blood glucose levels in the later stages of starvation?
What happens to blood glucose levels in the later stages of starvation?
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What is a direct consequence of excessive ketone body production during prolonged starvation?
What is a direct consequence of excessive ketone body production during prolonged starvation?
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Which process is primarily responsible for the breakdown of fats during starvation?
Which process is primarily responsible for the breakdown of fats during starvation?
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What notable metabolic state is observed during ketosis?
What notable metabolic state is observed during ketosis?
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During starvation, which of the following processes is decreased specifically in relation to ketone body metabolism?
During starvation, which of the following processes is decreased specifically in relation to ketone body metabolism?
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In what condition can severe ketosis lead to a state of coma or death?
In what condition can severe ketosis lead to a state of coma or death?
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What is the main process through which muscle cells experience glucose deprivation during starvation?
What is the main process through which muscle cells experience glucose deprivation during starvation?
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What is the effect of incomplete fatty acid oxidation seen during starvation?
What is the effect of incomplete fatty acid oxidation seen during starvation?
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What primary role does the liver play during the early stages of starvation?
What primary role does the liver play during the early stages of starvation?
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Which metabolic process does the liver primarily initiate in response to prolonged fasting?
Which metabolic process does the liver primarily initiate in response to prolonged fasting?
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What effect does starvation have on nitrogen balance over time?
What effect does starvation have on nitrogen balance over time?
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What happens to functional protein levels in the body as starvation continues?
What happens to functional protein levels in the body as starvation continues?
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During starvation, what biochemical change is observed in body water levels?
During starvation, what biochemical change is observed in body water levels?
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What ion is particularly reduced in the body during starvation, affecting electrolyte balance?
What ion is particularly reduced in the body during starvation, affecting electrolyte balance?
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Which condition may result from prolonged starvation due to biochemical changes?
Which condition may result from prolonged starvation due to biochemical changes?
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What is the role of ketogenesis in the body during starvation?
What is the role of ketogenesis in the body during starvation?
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How does acidic blood pH relate to metabolic changes during starvation?
How does acidic blood pH relate to metabolic changes during starvation?
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What is the primary role of the kidneys during starvation?
What is the primary role of the kidneys during starvation?
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Which of the following statements about ammonia detoxification in starvation is correct?
Which of the following statements about ammonia detoxification in starvation is correct?
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How do kidneys respond to the changes in metabolism during starvation?
How do kidneys respond to the changes in metabolism during starvation?
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Which hormone's change during starvation directly affects kidney function?
Which hormone's change during starvation directly affects kidney function?
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In the context of starvation, how does the kidney regulate blood glucose levels?
In the context of starvation, how does the kidney regulate blood glucose levels?
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Which process is least likely to be enhanced by kidney function during prolonged starvation?
Which process is least likely to be enhanced by kidney function during prolonged starvation?
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What role do the kidneys play in relation to fatty acids during starvation?
What role do the kidneys play in relation to fatty acids during starvation?
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What is the impact of prolonged starvation on kidney filtration rates?
What is the impact of prolonged starvation on kidney filtration rates?
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Which of the following is a consequence of hormonal changes during starvation for kidney function?
Which of the following is a consequence of hormonal changes during starvation for kidney function?
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Which adaptation of the kidneys primarily helps maintain homeostasis during starvation?
Which adaptation of the kidneys primarily helps maintain homeostasis during starvation?
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In starvation, which process mainly reduces the workload on the kidneys?
In starvation, which process mainly reduces the workload on the kidneys?
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What is the primary metabolic change that occurs in the kidneys during starvation?
What is the primary metabolic change that occurs in the kidneys during starvation?
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Which adaptation of the kidneys helps to manage electrolyte balance during periods of starvation?
Which adaptation of the kidneys helps to manage electrolyte balance during periods of starvation?
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How do the kidneys contribute to the maintenance of blood glucose levels during prolonged starvation?
How do the kidneys contribute to the maintenance of blood glucose levels during prolonged starvation?
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Which of the following statements about the kidney's role during starvation is correct?
Which of the following statements about the kidney's role during starvation is correct?
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What effect does prolonged starvation have on the kidneys' ammonia detoxification mechanisms?
What effect does prolonged starvation have on the kidneys' ammonia detoxification mechanisms?
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What primary metabolic role do kidneys play during the fasting state?
What primary metabolic role do kidneys play during the fasting state?
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Which of the following processes is least likely to be involved in kidney function during prolonged starvation?
Which of the following processes is least likely to be involved in kidney function during prolonged starvation?
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In the context of starvation, how do kidneys assist in maintaining electrolyte balance?
In the context of starvation, how do kidneys assist in maintaining electrolyte balance?
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What happens to the reabsorption of glucose in the kidneys during fasting?
What happens to the reabsorption of glucose in the kidneys during fasting?
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Which metabolite is primarily regulated by the kidneys during prolonged fasting?
Which metabolite is primarily regulated by the kidneys during prolonged fasting?
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How does the change in blood pH during starvation affect kidney function?
How does the change in blood pH during starvation affect kidney function?
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What impact does starvation have on the filtration rate in the kidneys?
What impact does starvation have on the filtration rate in the kidneys?
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Which renal function primarily decreases as a response to prolonged fasting?
Which renal function primarily decreases as a response to prolonged fasting?
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What is primarily decreased in the liver during prolonged starvation concerning carbohydrate metabolism?
What is primarily decreased in the liver during prolonged starvation concerning carbohydrate metabolism?
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Which condition is characterized by high levels of ketone bodies in the blood during starvation?
Which condition is characterized by high levels of ketone bodies in the blood during starvation?
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What process occurs in the liver during starvation that leads to the creation of glucose from non-carbohydrate sources?
What process occurs in the liver during starvation that leads to the creation of glucose from non-carbohydrate sources?
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What is a notable effect of lipid metabolism during starvation?
What is a notable effect of lipid metabolism during starvation?
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Which of the following processes related to fatty acids is decreased during starvation?
Which of the following processes related to fatty acids is decreased during starvation?
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What serious condition may arise due to uncontrolled ketosis during prolonged starvation?
What serious condition may arise due to uncontrolled ketosis during prolonged starvation?
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In terms of glucose availability to muscle cells during starvation, which effect is commonly observed?
In terms of glucose availability to muscle cells during starvation, which effect is commonly observed?
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What is a primary reason for the decline in blood glucose levels during later stages of starvation?
What is a primary reason for the decline in blood glucose levels during later stages of starvation?
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Which statement accurately describes ketogenesis during starvation?
Which statement accurately describes ketogenesis during starvation?
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What physiological condition can occur due to severe ketosis during starvation?
What physiological condition can occur due to severe ketosis during starvation?
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What is not a significant adaptation of the kidneys during starvation?
What is not a significant adaptation of the kidneys during starvation?
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In prolonged starvation, which of the following changes is least likely to occur in kidney function?
In prolonged starvation, which of the following changes is least likely to occur in kidney function?
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How does the body manage nitrogen balance during the early stages of starvation?
How does the body manage nitrogen balance during the early stages of starvation?
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Which effect of starvation on the kidneys contributes to maintaining blood glucose levels?
Which effect of starvation on the kidneys contributes to maintaining blood glucose levels?
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What is the primary electrolyte change observed in the kidneys during starvation?
What is the primary electrolyte change observed in the kidneys during starvation?
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Which role do the kidneys play in response to elevated ketone bodies during starvation?
Which role do the kidneys play in response to elevated ketone bodies during starvation?
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What is a potential consequence of acid-base imbalance in the kidneys during prolonged starvation?
What is a potential consequence of acid-base imbalance in the kidneys during prolonged starvation?
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During starvation, what mechanism involves the kidneys' response to maintain osmotic balance?
During starvation, what mechanism involves the kidneys' response to maintain osmotic balance?
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In what way does the reduction of functional protein levels during starvation affect kidney function?
In what way does the reduction of functional protein levels during starvation affect kidney function?
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Which of the following changes in kidney function is least likely to contribute to metabolic flexibility during starvation?
Which of the following changes in kidney function is least likely to contribute to metabolic flexibility during starvation?
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What are the primary hormones secreted by the pancreas that respond to changes in blood glucose during starvation?
What are the primary hormones secreted by the pancreas that respond to changes in blood glucose during starvation?
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During which stage of starvation does the body primarily utilize lipolysis and fatty acid oxidation?
During which stage of starvation does the body primarily utilize lipolysis and fatty acid oxidation?
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What is the role of ketogenesis during starvation?
What is the role of ketogenesis during starvation?
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How does the body respond hormonally to increase blood glucose in response to starvation?
How does the body respond hormonally to increase blood glucose in response to starvation?
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Which hormone is NOT typically associated with increasing blood glucose levels during starvation?
Which hormone is NOT typically associated with increasing blood glucose levels during starvation?
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In what way does cortisol affect metabolism during starvation?
In what way does cortisol affect metabolism during starvation?
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What physiological change occurs most significantly in response to prolonged starvation with respect to energy utilization?
What physiological change occurs most significantly in response to prolonged starvation with respect to energy utilization?
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Which of the following processes primarily occurs in the first stage of starvation?
Which of the following processes primarily occurs in the first stage of starvation?
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Which of the following substances primarily serves as an alternative fuel source for the brain during prolonged starvation?
Which of the following substances primarily serves as an alternative fuel source for the brain during prolonged starvation?
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The secretion of which hormone is primarily stimulated by low blood glucose levels during starvation?
The secretion of which hormone is primarily stimulated by low blood glucose levels during starvation?
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Study Notes
Biochemistry of Starvation
- Starvation is the complete stoppage of eating food by a human body.
- Total starvation is the complete stoppage of both food and water intake.
- Conditions leading to starvation include: food scarcity (droughts, floods, famine), extreme poverty, being lost at sea, major surgeries, severe burns, critical health issues, desire for rapid weight loss, and political factors like hunger strikes.
- Starvation can be caused by natural calamities, like droughts and floods, or extended periods at sea, or clinical conditions such as major surgeries and severe burns. It can also be caused by extreme poverty. Individuals may also choose to starve themselves, such as via hunger strikes in political protest, or for rapid weight loss.
Effects of Starvation on the Body
- No exogenous food intake means no external nutrients.
- Deprivation in starvation leads to lack of essential elements, including calories (carbohydrates and lipids), building blocks (proteins), growth factors (vitamins and minerals), and protectors (antioxidants).
Body's Response to Starvation
- Metabolic stress leads to significant metabolic stress as nutrients are lacking.
- The body enters an emergency state, prioritizing survival mechanisms.
- The starved body adapts to external resource shortage.
- The body relies on endogenous reserves (internal) to manage energy and nutrient needs.
Survival Period During Starvation
- Survival heavily relies on fat reserves in adipocytes (fat cells).
- Higher triacylglycerol (TAG) content in adipocytes results in longer survival.
- Survival time with only food deprivation is typically 3-4 weeks, potentially up to 65 days.
- Survival with only water deprivation is limited to a few days, typically less than a week.
Stages of Starvation
- Phase 1 (Glycogen Depletion): First 24 hours, body uses stored glycogen for energy.
- Phase 2 (Fat Burning): Days 2-7, body breaks down fat for energy, producing ketone bodies.
- Phase 3 (Muscle Wasting): After a week, body breaks down muscle protein for essential functions, and vital organ function may be compromised.
Adaptations and Biochemical Changes in Starvation
- Effects: No external food intake, depletion of essential nutrients, body in metabolic stress.
- Adaptations: Use of stored fats and proteins for energy, adjusting to relying on internal reserves, prioritizing survival mechanisms.
- Biochemical Alterations: Hormonal influence (glucagon and epinephrine activate), metabolic pathways are enhanced, hormones improve survival response.
Biochemical Adaptations in Starvation
- Stages: Multiple phases of starvation
- Metabolism: Changes in energy production and nutrient usage
- Organs: Effects on various body systems
- Stages: Glycogenolysis (breakdown of glycogen), Gluconeogenesis (creation of glucose), Lipolysis and fatty acid oxidation, Ketogenesis (production of ketones).
Hormonal Adaptations in Starvation
- Insulin: Decreases blood glucose (fed state), increases blood glucose (fasted state)
- Glucagon: Increases blood glucose, stimulates glucose production.
- Epinephrine: Increases blood glucose, prepares the body for rapid action.
- Cortisol: Maintains blood glucose level increase.
- Somatostatin: Increases blood glucose.
Carbohydrate Metabolism in the Liver During Starvation
- Increased Processes: Glycogenolysis (breakdown of glycogen) and Gluconeogenesis (creation of glucose from non-carbohydrates).
- Decreased Processes: Glycogenesis (glycogen formation), Glycolysis (glucose breakdown), TCA Cycle (energy cycle), HMP Shunt (alternative glucose pathway).
- Effects on Glucose: Blood glucose declines, cellular glucose deprivation in muscle cells.
Lipid Metabolism During Starvation
- Increased Processes: Lipolysis (fat breakdown), free fatty acid mobilization, beta oxidation of fatty acids, incomplete fatty acid oxidation, ketogenesis (ketone production).
- Decreased Processes: Ketolysis (ketone utilization), lipogenesis (fat synthesis).
- Notable Effects: Ketosis (can lead to ketoacidosis).
Protein Metabolism in Starvation
- Increased Processes: Muscle protein catabolism (muscle breakdown), transdeamination (releasing glucogenic amino acids).
- Nitrogen Balance: Ammonia detoxification and urea production initially increase, then decrease over time. Body enters negative nitrogen balance.
- Protein Reduction: Functional Protein levels decrease.
Water and Electrolyte Changes in Starvation
- Key Alterations: Body water reduction, potassium ion decrease, acidic blood pH due to increased ketone bodies.
- Prolonged Starvation Effects: Severe dehydration, acid-base imbalance, and electrolyte imbalances.
Role of the Liver in Starvation
- Primary Site for Gluconeogenesis: Converts non-carbohydrate sources into glucose during early starvation.
- Maintains blood glucose for organs like the brain.
- Key Role in Ketogenesis: Converts fatty acids to ketone bodies during prolonged fasting.
- Ketones serve as an alternative fuel.
- Adaptive Function in Starvation: Balances glucose and ketone production, conserving muscle protein.
Role of Muscles in Starvation
- Amino Acid Supply for Gluconeogenesis: Provides amino acids during early starvation for the liver to produce glucose.
- Muscle preservation: Reduces muscle protein breakdown to conserve muscle mass.
- Metabolic Adaptation: Uses fatty acids and ketones directly, reducing glucose demand and conserving muscle mass.
Role of the Brain in Starvation
- Initial Dependence on Glucose: Primarily uses glucose from glycogen and gluconeogenesis in early fasting.
- Shift to Ketone Utilization: Gradually adapts to ketone bodies for energy during prolonged fasting (up to 70% of needs).
- Metabolic Adaptation: Conserves muscle protein by reducing glucose demand, preserving lean body mass.
Role of Adipose Tissues in Starvation
- Primary Energy Reserve: Mobilizes stored triglycerides and provides energy during starvation via lipolysis (fat breakdown).
- Lipolysis and Fatty Acid Release: Breaks down triglycerides into free fatty acids and glycerol for energy.
- Adaptation to Prolonged Starvation: Supports ketone production and reduces protein breakdown, preserving muscle tissue.
Comparison of Fed and Fasting States
- Hormones: Insulin (fed), glucagon, adrenaline, & cortisol (fasting)
- Body Response: Hyperglycemia/glycogenesis (fed), hypoglycemia/lipolysis/ketogenesis/proteolysis (fasting)
- Source of Glucose: Food (fed) and glycogen/gluconeogenesis (fasting)
- Fate of Glucose: Glycolysis in both situations.
Liver: Fed vs. Fasted State
- Fed: Various enzymes like glucokinase, glycogen synthase, and phosphofructokinase are activated to promote glucose storage and utilization.
- Fasted: Other enzymes, such as glycogen phosphorylase, fructose-1,6-diphosphatase, and pyruvate kinase, become activated to stimulate glycogen breakdown and glucose production.
Assignment 2
- Explain different starvation stages and associated biochemical changes.
- Explain Role of Stages, Metabolism, and Organs during Starvation.
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Description
Explore the biochemistry behind starvation and its effects on the human body. This quiz covers various conditions leading to starvation, the body's physiological response, and the crucial nutrients that become deficient during this state. Test your understanding of metabolic stress and survival mechanisms.
