Biochemistry III - Metabolic Adaptations

Flashcards on Metabolic Adaptations of the Body in Well-Fed and Starvation Conditions

Well-Fed Condition (Postprandial State)

Occurs after a meal and lasts approximately 2-4 hours, characterized by nutrient availability promoting energy storage and growth.

Glucose

Primary energy source during the well-fed state, derived from dietary carbohydrates.

Insulin

Hormone that facilitates glucose uptake by cells, stimulates anabolic processes, and promotes fat storage while inhibiting lipolysis.

Glycogenesis

Storage of excess glucose as glycogen in the liver and muscle.

Lipogenesis

Conversion of excess glucose and dietary fats into triglycerides for storage in adipose tissue.

Lipolysis

Breakdown of stored fat, inhibited by insulin during the well-fed state.

Liver

Organ that processes and stores excess nutrients during the well-fed state through glycogen synthesis, lipogenesis, and protein synthesis.

Muscles

Actively participate in metabolism, utilizing and storing energy through glucose uptake, glycogen synthesis, and protein synthesis.

Brain

Relies solely on glucose for energy and cannot store fuel, dependent on a constant glucose supply.

Adipose Tissue

Primary storage for excess energy; insulin promotes lipogenesis and inhibits lipolysis for efficient nutrient storage.

Metabolic State in Starvation

Metabolic process shifting towards catabolism during starvation, where stored reserves are broken down to maintain vital functions.

Starvation

Prolonged food deprivation, triggering metabolic adaptations.

Fasting Condition

Shift from glucose metabolism to fat and ketone utilization, conserving energy and utilizing available resources efficiently.

Key Metabolic Processes During Starvation

Key processes during starvation including glycogenolysis, gluconeogenesis, lipolysis, and ketogenesis.

Glycogenolysis

The breakdown of glycogen stored in the liver, providing a readily available glucose source.

Gluconeogenesis

Production of glucose from non-carbohydrate sources that becomes essential for maintaining blood glucose levels during prolonged starvation.

Lipolysis

Breakdown of stored triglycerides into glycerol and free fatty acids, crucial for energy production during starvation.

Ketogenesis

Production of ketone bodies from fatty acids in the liver mitochondria during prolonged starvation.

Protein Catabolism

Breakdown of proteins into amino acids, used as an energy source during prolonged starvation.

Insulin Levels

Decreases during starvation to promote fat breakdown and ketogenesis.

Glucagon Levels

Increases during starvation to stimulate gluconeogenesis and glycogenolysis.

Cortisol Levels

Rises during starvation to enhance protein breakdown.

Epinephrine Levels

Increases during starvation to promote lipolysis.

Glucagon Role

Stimulates glycogenolysis and gluconeogenesis to ensure a steady glucose supply.

Epinephrine Role

Promotes fat breakdown and inhibits insulin activity to conserve glucose.

Cortisol Role

Enhances protein catabolism for gluconeogenesis and suppresses insulin sensitivity.

Liver Metabolism in Starvation

Initiates gluconeogenesis, ketogenesis, and glycogenolysis during starvation to maintain energy balance.

Muscle Metabolism in Starvation

Shifts metabolism towards energy conservation involving protein catabolism, fatty acid oxidation, and ketone utilization during starvation.

Brain Adaptation in Starvation

Adapts to utilize ketone bodies during prolonged starvation, preserving muscle protein.

Adipose Tissue in Starvation

Undergoes lipolysis to release fatty acids and glycerol into the bloodstream during starvation.

Muscle Wasting (Prolonged Starvation)

Leads to atrophy due to breakdown of muscle protein for gluconeogenesis.

Metabolic Rate Reduction (Prolonged Starvation)

Occurs to conserve energy, leading to decreased body temperature and slowed bodily functions.

Immune Suppression (Starvation)

Weakens the immune system, increasing susceptibility to infections.

Organ Failure (Prolonged Starvation)

Can occur in extreme cases, affecting vital organs and leading to irreversible damage.

Weight Loss (Starvation)

Significant result of starvation, as the body breaks down its own tissues for energy.

Nutritional Deficiencies (Starvation)

Starvation deprives the body of essential vitamins and minerals, affecting various bodily functions.

Metabolic Complications (Starvation)

Prolonged starvation can disrupt metabolic pathways, leading to imbalances and organ damage.

Psychological Effects (Starvation)

Leads to anxiety, depression, irritability, and cognitive impairments during starvation.

Muscle Wasting (Clinical Consequences)

Results from breakdown of muscle proteins for energy production, impairing physical function.

Hypoglycemia (Clinical Consequences)

Results from depletion of glycogen stores and reduced gluconeogenesis, leading to fatigue and dizziness.

Ketosis (Clinical Consequences)

Produced as an alternative fuel source during prolonged starvation, potentially leading to health issues.

Immune Suppression (Clinical Consequences)

Compromised during starvation, increasing susceptibility to infections.

Organ Failure (Clinical Consequences)

Can occur during prolonged starvation, especially affecting the liver, kidneys, and heart.

Malnutrition and Anorexia

A condition characterized by insufficient food intake and potentially severe metabolic imbalances.

Fasting Therapies

Therapies requiring careful consideration due to potential risks of metabolic complications.

Refeeding Syndrome

A life-threatening condition that can occur during rapid nutrient replenishment, leading to imbalances and organ dysfunction.

Gradual Refeeding

Essential to minimize the risk of Refeeding Syndrome, allowing the body to adapt to nutrient availability.