1. Stress
2. Energy metabolism, fasting and malnutrition
3. Collapse and shock
4. Endotoxicosis
5. Metabolic syndrome
6. ARDS
7. Multiple organ failure
8. Chronic pain

• 50 self-control questions at the end, arranged chapter-wise, or
• 16 situational cases, or
• both.

1. Stress
2. Energy metabolism, fasting and malnutrition
3. Collapse and shock
4. Endotoxicosis
5. Metabolic syndrome
6. ARDS
7. Multiple organ failure
8. Chronic pain

• 50 self-control questions at the end, arranged chapter-wise, or
• 16 situational cases, or
• both.You mean the Plan topics listed at the beginning of each of the 8 chapters, not the self-control questions or clinical cases. There are 59 plan topics in total, so I will prepare answers chapter-wise, starting with one chapter at a time.

1. Stress: 9 topics
2. Energy metabolism, fasting and malnutrition: 10 topics
3. Collapse and shock: 5 topics
4. Endotoxicosis: 8 topics
5. Metabolic syndrome: 6 topics
6. Acute respiratory distress syndrome: 5 topics
7. Multiple organ failure: 5 topics
8. Chronic pain: 12 topics

1. Stress
2. Energy metabolism, fasting and malnutrition
3. Collapse and shock
4. Endotoxicosis
5. Metabolic syndrome
6. ARDS
7. Multiple organ failure
8. Chronic pain

• 50 self-control questions at the end, arranged chapter-wise, or
• 16 situational cases, or
• both.You mean the Plan topics listed at the beginning of each of the 8 chapters, not the self-control questions or clinical cases. There are 59 plan topics in total, so I will prepare answers chapter-wise, starting with one chapter at a time.The eight chapters and their plan topics are:

1. Stress: 9 topics
2. Energy metabolism, fasting and malnutrition: 10 topics
3. Collapse and shock: 5 topics
4. Endotoxicosis: 8 topics
5. Metabolic syndrome: 6 topics
6. Acute respiratory distress syndrome: 5 topics
7. Multiple organ failure: 5 topics
8. Chronic pain: 12 topics

Chapter 1. Pathophysiology of Stress

1. Stress as a nonspecific response to damage. Types of stress

• Acute stress: short-term response, mainly involving catecholamines. It may end after the alarm stage.
• Chronic stress: prolonged or repeated stress, with sustained glucocorticoid effects and risk of maladaptation.
• Eustress: adaptive stress in which resistance and functional capacity increase.
• Distress: harmful stress in which adaptive reserves are inadequate or depleted, causing disease.
• By origin, stressors may be physical, chemical, biological, social, or emotional.

2. Causes and main pathways of the stress reaction

1. Sympathetic-adrenal system
   • Hypothalamic and autonomic activation causes release of adrenaline and noradrenaline.
   • Produces tachycardia, increased cardiac output and blood pressure, bronchodilation, glycogenolysis, lipolysis, and redistribution of blood toward the heart, brain, and skeletal muscles.
2. Hypothalamic-pituitary-adrenal axis
   • Hypothalamus releases corticotropin-releasing hormone (CRH).
   • CRH stimulates pituitary release of ACTH.
   • ACTH stimulates adrenal cortex secretion of cortisol.
   • Cortisol maintains vascular responsiveness to catecholamines, promotes gluconeogenesis and lipolysis, and suppresses excessive inflammation and immune activity.
3. Renin-angiotensin-aldosterone system and vasopressin
   • Cause sodium and water retention, reduced urine output, and maintenance of circulating blood volume and arterial pressure.

3. General adaptation syndrome

Stages

1. Alarm stage
   • Lasts from hours to about 48 hours.
   • Sympathetic-adrenal activation predominates.
   • Main hormone: adrenaline.
   • Findings: tachycardia, increased blood pressure, bronchodilation, hyperglycemia, glycogenolysis, increased metabolic rate, blood-flow centralization, and activation of coagulation.
2. Resistance stage
   • Develops after about 48 hours if the stressor persists.
   • Main hormone: cortisol.
   • The body develops increased specific and nonspecific resistance.
   • Effects: gluconeogenesis, hyperglycemia, lipolysis, anti-inflammatory and immunosuppressive actions, sodium and water retention, and maintenance of vascular tone.
3. Exhaustion stage
   • Occurs when stress is excessively intense or prolonged.
   • Adaptive reserves fail, especially adrenal cortical function.
   • Findings: reduced glucocorticoid production, hypotension, hypoglycemia, hypothermia, protein catabolism, oxidative stress, cellular damage, and possible organ failure or death.

• thymus and lymphoid tissue involution;
• adrenal cortical hypertrophy;
• gastric and duodenal ulceration.

4. Pathogenetic features of emotional stress

• limbic structures, especially fear and anxiety circuits;
• sympathetic-adrenal system;
• hypothalamic-pituitary-adrenal axis.

• hypertension and coronary disease;
• sleep disturbance, anxiety, depression, and cognitive impairment;
• hyperglycemia and insulin resistance;
• immune suppression;
• gastrointestinal disorders;
• reproductive dysfunction.

5. Main stress-limiting systems and their role

6. Role of stress in cardiovascular disease

• Increased heart rate and cardiac workload.
• Persistent vasoconstriction and increased peripheral resistance.
• Activation of the renin-angiotensin-aldosterone system.
• Sodium and water retention, increasing blood volume.
• Endothelial dysfunction.
• Hyperglycemia, dyslipidemia, and accelerated atherosclerosis.
• Increased platelet activation and coagulation tendency.

• arterial hypertension;
• coronary heart disease;
• atherosclerosis;
• myocardial infarction;
• stroke;
• arrhythmias and heart failure.

7. Role of stress in gastrointestinal disease

1. Vasoconstriction causes mucosal ischemia and hypoxia.
2. Mucus and bicarbonate protection decrease.
3. Adrenaline may increase hydrochloric acid secretion.
4. The mucosal barrier becomes more permeable and vulnerable.
5. If Helicobacter pylori is present, the risk of gastritis and peptic ulcer rises further.

• stress gastritis;
• gastric and duodenal ulceration;
• gastrointestinal bleeding;
• worsening of inflammatory bowel disease, including ulcerative colitis.

8. Stress in immunodeficiency, mental disorders, cancer, and other disease

Secondary immunodeficiency

Mental and neurotic disorders

Obesity and diabetes

Cancer

Reproductive dysfunction

9. Post-traumatic stress disorder

• intrusive traumatic memories and flashbacks;
• nightmares;
• avoidance of trauma-related thoughts, people, or places;
• hypervigilance, anxiety, irritability, and exaggerated startle response;
• dissociation or amnesia;
• symptoms persisting for more than one month and causing functional impairment.

1. Severe trauma strongly activates the sympathetic-adrenal system and HPA axis.
2. Dysregulation of glucocorticoid negative feedback develops.
3. Persistent emotional-memory activation occurs, involving the amygdala and limbic system.
4. Hippocampal and cortical dysfunction impairs memory integration and rational evaluation of danger.
5. Trauma-associated cues become conditioned triggers, producing automatic defensive reactions.
6. Repeated arousal and re-experiencing maintain a vicious cycle of stress activation and neural dysfunction.

Chapter 2. Energy Metabolism Disorders, Fasting and Malnutrition

1. Stages of energy metabolism and types of disorders

1. Digestion and absorption
   Dietary carbohydrates, fats, and proteins are broken into monomers and absorbed from the gastrointestinal tract.
2. Formation of common intermediates
   Monomers are converted mainly into acetyl-CoA.
3. Final oxidation
   Acetyl-CoA enters the Krebs cycle and respiratory chain, producing ATP through oxidative phosphorylation.

• Disorders of energy production
  • Hypoxia or ischemia
  • Lack of nutrient substrates
  • Enzyme defects in glycolysis, Krebs cycle, or respiratory chain
  • Mitochondrial dysfunction
  • Uncoupling of oxidation from phosphorylation
• Disorders of energy transport
  • Mainly in skeletal and cardiac muscle.
  • Caused by defective creatine-phosphate shuttle, which transports high-energy phosphate from mitochondria to myofibrils.
• Disorders of ATP utilization
  • Occur when ATPase activity or ATPase expression decreases.
  • ATP is present but cannot be effectively used for cell work.

2. Definition and classification of fasting

Classification

1. Absolute fasting
   • No food and no water intake.
   • Death usually occurs within 5-7 days, mainly due to severe dehydration and water-electrolyte imbalance.
2. Complete fasting with water
   • Food is absent, but water is available.
   • Average survival: about 65-70 days.
3. Incomplete fasting or undernutrition
   • Food intake is insufficient for total energy and plastic needs.
4. Partial fasting or unbalanced nutrition
   • Calories may be adequate, but specific nutrients are deficient, such as proteins, essential fats, vitamins, or trace elements.
5. Endogenous starvation or malnutrition
   • Inadequate nutrition due to disease, impaired digestion or absorption, chronic inflammation, increased catabolism, nutrient losses, or appetite disorders.

3. Changes during complete fasting with water

A. Adaptive period

• Liver glycogen is rapidly consumed.
• Glucose is then formed by gluconeogenesis from alanine, glutamine, glycerol, and lactate.
• Catecholamines and glucocorticoids increase glycogenolysis and gluconeogenesis.
• Body-weight loss and basal metabolic rate are maximal.

B. Stationary period

• Begins when fat oxidation increases and ketone bodies rise, usually from day 5-6.
• The brain increasingly uses ketone bodies, reducing the need for glucose and sparing protein.
• Typical changes:
  • lethargy, apathy, reduced memory and attention;
  • bradycardia and hypotension;
  • bradypnea and reduced vital lung capacity;
  • reduced gastrointestinal secretion and motility;
  • anemia;
  • secondary immunodeficiency;
  • hypothyroidism and hypothermia, reducing basal metabolism.

C. Terminal period

• Occurs after loss of approximately 40-50% of body weight.
• Fat reserves are depleted, so essential intracellular proteins are broken down.
• Increased degradation of nucleic acids causes increased non-protein nitrogen in blood.
• Severe intoxication, organ dysfunction, and death result.
• Feeding at this stage is often ineffective and may be dangerous.

4. Protein-energy malnutrition

Main forms

• weight loss;
• negative nitrogen balance;
• hypoproteinemia or dysproteinemia;
• edema due to hypoalbuminemia;
• reduced synthesis of enzymes, hormones, antibodies, and structural proteins;
• hypothermia;
• impaired water-electrolyte and acid-base balance;
• increased infection risk.

5. Malnutrition and cachexia

• unintentional weight loss;
• low body mass index;
• reduced muscle mass.

• reduced food intake or malabsorption;
• acute or chronic inflammation due to disease.

• malignant tumors;
• chronic heart failure;
• chronic infection;
• autoimmune and inflammatory disease;
• prolonged fever;
• severe chronic organ disease.

6. Impaired digestion and absorption: malabsorption syndrome

• chronic diarrhea;
• weight loss;
• protein deficiency and peripheral edema;
• vitamin and trace-element deficiency;
• anemia;
• weakness and muscle wasting.

Types

1. Primary malabsorption
   • Caused by inherited defects of digestive enzymes or membrane transporters.
   • Examples: congenital monosaccharide or amino-acid malabsorption.
2. Secondary malabsorption
   • Caused by disease affecting digestion or intestinal mucosa.
   • Forms:
     • gastrogenic: impaired gastric digestion;
     • hepatogenic: inadequate bile formation or delivery;
     • pancreatogenic: pancreatic enzyme deficiency;
     • enterogenic: disease or damage of small-intestinal mucosa.

7. Conditions with long-term elevation of proinflammatory cytokines

Cancer cachexia

1. Tumor and immune cells produce proinflammatory cytokines.
2. TNF-alpha, IL-6, and lipid-mobilizing factors activate lipolysis and inhibit triglyceride synthesis.
3. White adipose tissue may transform toward beige adipose tissue, increasing thermogenesis and energy expenditure.
4. Cytokine-mediated neuroinflammation suppresses hypothalamic appetite-stimulating pathways.
5. Protein synthesis and muscle regeneration decline, while autophagy and proteolysis increase.
6. Tumor cells consume glucose, amino acids, and fatty acids, effectively competing with normal tissue.

Cachexia in chronic heart failure

• hypoxia and reduced tissue perfusion;
• venous congestion and intestinal mucosal edema;
• malabsorption;
• loss of appetite;
• sympathetic hyperactivation;
• increased proinflammatory cytokines;
• bacterial translocation from the intestine;
• skeletal-muscle dysfunction and impaired regeneration.

8. Disorders of endocrine regulation of metabolism

• Hyperthyroidism
  • Increases basal metabolic rate, oxygen consumption, lipolysis, and protein breakdown.
  • Causes weight loss despite increased appetite.
• Glucagon excess
  • Increases glycogenolysis, gluconeogenesis, and lipolysis.
• Type 1 diabetes mellitus with insulin deficiency
  • Cells cannot adequately use glucose.
  • Lipolysis and proteolysis increase.
  • Hyperglycemia causes osmotic diuresis and dehydration.
  • Weight loss and ketoacidosis can develop.
• Excess glucocorticoids
  • Promote proteolysis, hyperglycemia, insulin resistance, and redistribution of fat.

9. Conditions causing loss of protein or nutrients

• burns: loss of protein-rich plasma through damaged skin;
• nephrotic syndrome: urinary protein loss;
• chronic diarrhea: loss of water, electrolytes, and nutrients;
• intestinal fistulas: loss of digestive secretions and proteins;
• chronic vomiting;
• lymphorrhea or chylous losses;
• cerebrospinal-fluid loss in some conditions.

10. Mental disorders and appetite-regulation disorders

Anorexia nervosa

Bulimia nervosa

Depression and schizophrenia

Anorexia of ageing

• reduced orexigenic signaling;
• inflammation;
• reduced taste and smell;
• poor dentition;
• dysphagia or hyposalivation;
• social isolation and depression.

Refeeding syndrome

1. Carbohydrate feeding raises insulin secretion.
2. Glucose, phosphate, potassium, magnesium, and water shift into cells.
3. Serum phosphate, potassium, and magnesium fall.
4. ATP production becomes impaired and fluid overload may occur.

• hypophosphatemia, hypokalemia, hypomagnesemia;
• edema and heart failure;
• arrhythmias;
• respiratory-muscle weakness and respiratory failure;
• seizures, delirium, and encephalopathy;
• rhabdomyolysis and possible death.

1. Stress
   • Stress response, stressors, and types of stress
   • Sympathetic-adrenal and HPA-axis pathways
   • General adaptation syndrome
   • Emotional stress, stress-limiting systems, and stress-related disease
   • PTSD
2. Energy metabolism, fasting, and malnutrition
   • Energy production, transport, and ATP-use disorders
   • Types and stages of fasting
   • Protein-energy malnutrition, cachexia, and malabsorption
   • Endocrine and psychiatric causes of malnutrition
   • Refeeding syndrome

1. Stress
2. Energy metabolism, fasting and malnutrition
3. Collapse and shock
4. Endotoxicosis
5. Metabolic syndrome
6. ARDS
7. Multiple organ failure
8. Chronic pain

• 50 self-control questions at the end, arranged chapter-wise, or
• 16 situational cases, or
• both.You mean the Plan topics listed at the beginning of each of the 8 chapters, not the self-control questions or clinical cases. There are 59 plan topics in total, so I will prepare answers chapter-wise, starting with one chapter at a time.The eight chapters and their plan topics are:

1. Stress: 9 topics
2. Energy metabolism, fasting and malnutrition: 10 topics
3. Collapse and shock: 5 topics
4. Endotoxicosis: 8 topics
5. Metabolic syndrome: 6 topics
6. Acute respiratory distress syndrome: 5 topics
7. Multiple organ failure: 5 topics
8. Chronic pain: 12 topics

1. Stress as a nonspecific response to damage. Types of stress

• Acute stress: short-term response, mainly involving catecholamines. It may end after the alarm stage.
• Chronic stress: prolonged or repeated stress, with sustained glucocorticoid effects and risk of maladaptation.
• Eustress: adaptive stress in which resistance and functional capacity increase.
• Distress: harmful stress in which adaptive reserves are inadequate or depleted, causing disease.
• By origin, stressors may be physical, chemical, biological, social, or emotional.

2. Causes and main pathways of the stress reaction

1. Sympathetic-adrenal system
   • Hypothalamic and autonomic activation causes release of adrenaline and noradrenaline.
   • Produces tachycardia, increased cardiac output and blood pressure, bronchodilation, glycogenolysis, lipolysis, and redistribution of blood toward the heart, brain, and skeletal muscles.
2. Hypothalamic-pituitary-adrenal axis
   • Hypothalamus releases corticotropin-releasing hormone (CRH).
   • CRH stimulates pituitary release of ACTH.
   • ACTH stimulates adrenal cortex secretion of cortisol.
   • Cortisol maintains vascular responsiveness to catecholamines, promotes gluconeogenesis and lipolysis, and suppresses excessive inflammation and immune activity.
3. Renin-angiotensin-aldosterone system and vasopressin
   • Cause sodium and water retention, reduced urine output, and maintenance of circulating blood volume and arterial pressure.

3. General adaptation syndrome

Stages

1. Alarm stage
   • Lasts from hours to about 48 hours.
   • Sympathetic-adrenal activation predominates.
   • Main hormone: adrenaline.
   • Findings: tachycardia, increased blood pressure, bronchodilation, hyperglycemia, glycogenolysis, increased metabolic rate, blood-flow centralization, and activation of coagulation.
2. Resistance stage
   • Develops after about 48 hours if the stressor persists.
   • Main hormone: cortisol.
   • The body develops increased specific and nonspecific resistance.
   • Effects: gluconeogenesis, hyperglycemia, lipolysis, anti-inflammatory and immunosuppressive actions, sodium and water retention, and maintenance of vascular tone.
3. Exhaustion stage
   • Occurs when stress is excessively intense or prolonged.
   • Adaptive reserves fail, especially adrenal cortical function.
   • Findings: reduced glucocorticoid production, hypotension, hypoglycemia, hypothermia, protein catabolism, oxidative stress, cellular damage, and possible organ failure or death.

• thymus and lymphoid tissue involution;
• adrenal cortical hypertrophy;
• gastric and duodenal ulceration.

4. Pathogenetic features of emotional stress

• limbic structures, especially fear and anxiety circuits;
• sympathetic-adrenal system;
• hypothalamic-pituitary-adrenal axis.

• hypertension and coronary disease;
• sleep disturbance, anxiety, depression, and cognitive impairment;
• hyperglycemia and insulin resistance;
• immune suppression;
• gastrointestinal disorders;
• reproductive dysfunction.

5. Main stress-limiting systems and their role

6. Role of stress in cardiovascular disease

• Increased heart rate and cardiac workload.
• Persistent vasoconstriction and increased peripheral resistance.
• Activation of the renin-angiotensin-aldosterone system.
• Sodium and water retention, increasing blood volume.
• Endothelial dysfunction.
• Hyperglycemia, dyslipidemia, and accelerated atherosclerosis.
• Increased platelet activation and coagulation tendency.

• arterial hypertension;
• coronary heart disease;
• atherosclerosis;
• myocardial infarction;
• stroke;
• arrhythmias and heart failure.

7. Role of stress in gastrointestinal disease

1. Vasoconstriction causes mucosal ischemia and hypoxia.
2. Mucus and bicarbonate protection decrease.
3. Adrenaline may increase hydrochloric acid secretion.
4. The mucosal barrier becomes more permeable and vulnerable.
5. If Helicobacter pylori is present, the risk of gastritis and peptic ulcer rises further.

• stress gastritis;
• gastric and duodenal ulceration;
• gastrointestinal bleeding;
• worsening of inflammatory bowel disease, including ulcerative colitis.

8. Stress in immunodeficiency, mental disorders, cancer, and other disease

Secondary immunodeficiency

Mental and neurotic disorders

Obesity and diabetes

Cancer

Reproductive dysfunction

9. Post-traumatic stress disorder

• intrusive traumatic memories and flashbacks;
• nightmares;
• avoidance of trauma-related thoughts, people, or places;
• hypervigilance, anxiety, irritability, and exaggerated startle response;
• dissociation or amnesia;
• symptoms persisting for more than one month and causing functional impairment.

1. Severe trauma strongly activates the sympathetic-adrenal system and HPA axis.
2. Dysregulation of glucocorticoid negative feedback develops.
3. Persistent emotional-memory activation occurs, involving the amygdala and limbic system.
4. Hippocampal and cortical dysfunction impairs memory integration and rational evaluation of danger.
5. Trauma-associated cues become conditioned triggers, producing automatic defensive reactions.
6. Repeated arousal and re-experiencing maintain a vicious cycle of stress activation and neural dysfunction.

1. Stages of energy metabolism and types of disorders

1. Digestion and absorption
   Dietary carbohydrates, fats, and proteins are broken into monomers and absorbed from the gastrointestinal tract.
2. Formation of common intermediates
   Monomers are converted mainly into acetyl-CoA.
3. Final oxidation
   Acetyl-CoA enters the Krebs cycle and respiratory chain, producing ATP through oxidative phosphorylation.

• Disorders of energy production
  • Hypoxia or ischemia
  • Lack of nutrient substrates
  • Enzyme defects in glycolysis, Krebs cycle, or respiratory chain
  • Mitochondrial dysfunction
  • Uncoupling of oxidation from phosphorylation
• Disorders of energy transport
  • Mainly in skeletal and cardiac muscle.
  • Caused by defective creatine-phosphate shuttle, which transports high-energy phosphate from mitochondria to myofibrils.
• Disorders of ATP utilization
  • Occur when ATPase activity or ATPase expression decreases.
  • ATP is present but cannot be effectively used for cell work.

2. Definition and classification of fasting

Classification

1. Absolute fasting
   • No food and no water intake.
   • Death usually occurs within 5-7 days, mainly due to severe dehydration and water-electrolyte imbalance.
2. Complete fasting with water
   • Food is absent, but water is available.
   • Average survival: about 65-70 days.
3. Incomplete fasting or undernutrition
   • Food intake is insufficient for total energy and plastic needs.
4. Partial fasting or unbalanced nutrition
   • Calories may be adequate, but specific nutrients are deficient, such as proteins, essential fats, vitamins, or trace elements.
5. Endogenous starvation or malnutrition
   • Inadequate nutrition due to disease, impaired digestion or absorption, chronic inflammation, increased catabolism, nutrient losses, or appetite disorders.

3. Changes during complete fasting with water

A. Adaptive period

• Liver glycogen is rapidly consumed.
• Glucose is then formed by gluconeogenesis from alanine, glutamine, glycerol, and lactate.
• Catecholamines and glucocorticoids increase glycogenolysis and gluconeogenesis.
• Body-weight loss and basal metabolic rate are maximal.

B. Stationary period

• Begins when fat oxidation increases and ketone bodies rise, usually from day 5-6.
• The brain increasingly uses ketone bodies, reducing the need for glucose and sparing protein.
• Typical changes:
  • lethargy, apathy, reduced memory and attention;
  • bradycardia and hypotension;
  • bradypnea and reduced vital lung capacity;
  • reduced gastrointestinal secretion and motility;
  • anemia;
  • secondary immunodeficiency;
  • hypothyroidism and hypothermia, reducing basal metabolism.

C. Terminal period

• Occurs after loss of approximately 40-50% of body weight.
• Fat reserves are depleted, so essential intracellular proteins are broken down.
• Increased degradation of nucleic acids causes increased non-protein nitrogen in blood.
• Severe intoxication, organ dysfunction, and death result.
• Feeding at this stage is often ineffective and may be dangerous.

4. Protein-energy malnutrition

Main forms

• weight loss;
• negative nitrogen balance;
• hypoproteinemia or dysproteinemia;
• edema due to hypoalbuminemia;
• reduced synthesis of enzymes, hormones, antibodies, and structural proteins;
• hypothermia;
• impaired water-electrolyte and acid-base balance;
• increased infection risk.

5. Malnutrition and cachexia

• unintentional weight loss;
• low body mass index;
• reduced muscle mass.

• reduced food intake or malabsorption;
• acute or chronic inflammation due to disease.

• malignant tumors;
• chronic heart failure;
• chronic infection;
• autoimmune and inflammatory disease;
• prolonged fever;
• severe chronic organ disease.

6. Impaired digestion and absorption: malabsorption syndrome

• chronic diarrhea;
• weight loss;
• protein deficiency and peripheral edema;
• vitamin and trace-element deficiency;
• anemia;
• weakness and muscle wasting.

Types

1. Primary malabsorption
   • Caused by inherited defects of digestive enzymes or membrane transporters.
   • Examples: congenital monosaccharide or amino-acid malabsorption.
2. Secondary malabsorption
   • Caused by disease affecting digestion or intestinal mucosa.
   • Forms:
     • gastrogenic: impaired gastric digestion;
     • hepatogenic: inadequate bile formation or delivery;
     • pancreatogenic: pancreatic enzyme deficiency;
     • enterogenic: disease or damage of small-intestinal mucosa.

7. Conditions with long-term elevation of proinflammatory cytokines

Cancer cachexia

1. Tumor and immune cells produce proinflammatory cytokines.
2. TNF-alpha, IL-6, and lipid-mobilizing factors activate lipolysis and inhibit triglyceride synthesis.
3. White adipose tissue may transform toward beige adipose tissue, increasing thermogenesis and energy expenditure.
4. Cytokine-mediated neuroinflammation suppresses hypothalamic appetite-stimulating pathways.
5. Protein synthesis and muscle regeneration decline, while autophagy and proteolysis increase.
6. Tumor cells consume glucose, amino acids, and fatty acids, effectively competing with normal tissue.

Cachexia in chronic heart failure

• hypoxia and reduced tissue perfusion;
• venous congestion and intestinal mucosal edema;
• malabsorption;
• loss of appetite;
• sympathetic hyperactivation;
• increased proinflammatory cytokines;
• bacterial translocation from the intestine;
• skeletal-muscle dysfunction and impaired regeneration.

8. Disorders of endocrine regulation of metabolism

• Hyperthyroidism
  • Increases basal metabolic rate, oxygen consumption, lipolysis, and protein breakdown.
  • Causes weight loss despite increased appetite.
• Glucagon excess
  • Increases glycogenolysis, gluconeogenesis, and lipolysis.
• Type 1 diabetes mellitus with insulin deficiency
  • Cells cannot adequately use glucose.
  • Lipolysis and proteolysis increase.
  • Hyperglycemia causes osmotic diuresis and dehydration.
  • Weight loss and ketoacidosis can develop.
• Excess glucocorticoids
  • Promote proteolysis, hyperglycemia, insulin resistance, and redistribution of fat.

9. Conditions causing loss of protein or nutrients

• burns: loss of protein-rich plasma through damaged skin;
• nephrotic syndrome: urinary protein loss;
• chronic diarrhea: loss of water, electrolytes, and nutrients;
• intestinal fistulas: loss of digestive secretions and proteins;
• chronic vomiting;
• lymphorrhea or chylous losses;
• cerebrospinal-fluid loss in some conditions.

10. Mental disorders and appetite-regulation disorders

Anorexia nervosa

Bulimia nervosa

Depression and schizophrenia

Anorexia of ageing

• reduced orexigenic signaling;
• inflammation;
• reduced taste and smell;
• poor dentition;
• dysphagia or hyposalivation;
• social isolation and depression.

Refeeding syndrome

1. Carbohydrate feeding raises insulin secretion.
2. Glucose, phosphate, potassium, magnesium, and water shift into cells.
3. Serum phosphate, potassium, and magnesium fall.
4. ATP production becomes impaired and fluid overload may occur.

• hypophosphatemia, hypokalemia, hypomagnesemia;
• edema and heart failure;
• arrhythmias;
• respiratory-muscle weakness and respiratory failure;
• seizures, delirium, and encephalopathy;
• rhabdomyolysis and possible death.

1. Stress
   • Stress response, stressors, and types of stress
   • Sympathetic-adrenal and HPA-axis pathways
   • General adaptation syndrome
   • Emotional stress, stress-limiting systems, and stress-related disease
   • PTSD
2. Energy metabolism, fasting, and malnutrition
   • Energy production, transport, and ATP-use disorders
   • Types and stages of fasting
   • Protein-energy malnutrition, cachexia, and malabsorption
   • Endocrine and psychiatric causes of malnutrition
   • Refeeding syndrome

Chapter 3. Pathophysiology of Collapse and Shock

1. Collapse: definition, classification, and fainting

Main types of collapse

• Orthostatic collapse: occurs on standing because venous return to the heart falls and venous vasoconstriction is inadequate.
• Hemorrhagic collapse: caused by rapid blood or plasma loss, for example trauma, severe diarrhea, or bleeding.
• Cardiogenic collapse: due to sudden fall in cardiac output, for example myocardial infarction, serious arrhythmia, myocarditis, or hemopericardium.
• Toxic collapse: caused by toxins, carbon monoxide, cyanide, radiation, high temperature, or severe endotoxemia.
• Infectious collapse: complication of severe infections due to microbial endo- and exotoxins.
• Hypoxic collapse: occurs in hypoxia, especially with low inspired oxygen tension and hypocapnia.
• Reflex collapse: may occur in severe pain, angina, or myocardial infarction.

Collapse versus shock

2. Main types of collapse: mechanisms and clinical manifestations

Orthostatic collapse

Hemorrhagic collapse

Cardiogenic collapse

Toxic and infectious collapse

3. Pathogenesis of collapse

A. Decreased vascular tone

• Arterioles and veins dilate because of direct vascular-wall injury, impaired vasomotor-center function, or abnormal angioreceptor response.
• Vascular capacity rises.
• Blood pools in the venous system.
• Venous return and cardiac output decline.
• Arterial hypotension and cerebral hypoperfusion develop.

B. Rapid fall in circulating blood volume

• Caused by blood loss, dehydration, plasma loss, or severe diarrhea.
• Venous return and cardiac output fall.
• Microcirculation becomes impaired.
• Tissue hypoxia causes anaerobic glycolysis and metabolic acidosis.
• Acidosis and hypoxia increase endothelial permeability, causing fluid to move into interstitial spaces and worsening hypovolemia.
• Platelet and erythrocyte aggregation and microthrombosis may occur.

4. Shock: definition, types, stages, and hemodynamics

Types by etiology

1. Hemorrhagic shock
2. Traumatic shock
3. Dehydration shock
4. Burn shock
5. Cardiogenic shock
6. Anaphylactic shock
7. Septic shock

Types by mechanism

Stages of shock

• Sympathetic activation, tachycardia, vasoconstriction, RAAS and ADH activation.
• Blood pressure may be normal or only mildly reduced.
• Cold pale skin, reduced pulse pressure, reduced diuresis, anxiety, and psychomotor agitation occur.
• Blood flow is centralized toward the brain and heart.

• Compensatory mechanisms fail.
• Severe arterial hypotension develops.
• Perfusion of the brain, heart, kidneys, and other organs decreases.
• Lactic acidosis, endothelial damage, capillary leakage, microthrombosis, and progressive organ dysfunction occur.

• Severe cellular injury, mitochondrial dysfunction, refractory acidosis, and multiple organ failure occur.
• Restoration of systemic circulation may no longer restore cell viability.

Shock index

• Normal: approximately 0.5-0.7
• Increasing value indicates worsening circulatory failure.
• A value near or above 1 is concerning for significant shock.

5. Traumatic shock and septic shock

A. Traumatic shock

1. Blood loss and hypovolemia
2. Tissue damage
3. Severe pain

Compensated phase: centralization of circulation

• Sympathetic-adrenal activation causes arteriolar vasoconstriction.
• Blood is redistributed to the brain, heart, adrenal glands, and diaphragm.
• RAAS and ADH retain sodium and water.
• Fluid shifts from tissues into capillaries, partially supporting blood volume.
• Diuresis decreases.

Decompensated phase: decentralization of circulation

• Hypoxia and acidosis damage vascular and cellular membranes.
• Proteolytic products and lipid-peroxidation products relax precapillary sphincters.
• Blood becomes trapped in capillaries, called the gateway phenomenon.
• Fluid leaves vessels, causing interstitial edema and further decreasing circulating volume.
• Intestinal ischemia permits endotoxin translocation.
• Acute kidney injury, ARDS, DIC, and multiple organ failure may develop.

Major mechanisms of multiple organ failure in traumatic shock

• tissue hypoperfusion;
• intestinal endotoxemia;
• DIC and microthrombi;
• hypoxia, ATP deficiency, and acidosis;
• systemic inflammatory mediators;
• endothelial dysfunction.

B. Septic shock

Pathogenesis

1. Microbial endo- and exotoxins activate macrophages, neutrophils, complement, and endothelium.
2. Cytokines, especially TNF-alpha, IL-1, and IL-6, generate systemic inflammation.
3. Nitric oxide and other mediators cause generalized vasodilation and reduced systemic vascular resistance.
4. Endothelial permeability increases, causing fluid leakage and reduced effective circulating volume.
5. Myocardial depression may develop early.
6. Coagulation activation causes microthrombosis and possible DIC.
7. Tissue oxygen utilization becomes impaired, resulting in lactic acidosis and organ failure.

Hemodynamic features

• Reduced vascular tone.
• Relative and absolute hypovolemia due to capillary leak.
• Cardiac output may initially be increased but becomes reduced with myocardial dysfunction.
• Blood pressure eventually falls despite compensatory mechanisms.

Clinical features

• Hypotension, tachycardia, tachypnea, altered mental status, oliguria, elevated lactate.
• Warm, flushed skin may occur early, followed by cool mottled skin in late shock.
• Features of systemic inflammation, respiratory failure, coagulation disturbance, and multiorgan dysfunction may be present.

General pathophysiological principles of shock management

• restore effective circulating volume;
• ensure oxygenation and ventilation;
• restore tissue perfusion and microcirculation;
• support cardiac function;
• correct acidosis and electrolyte disorders;
• maintain renal perfusion and urine output;
• correct coagulopathy;
• treat the cause, such as hemorrhage control, infection source control, antibiotics, or treatment of anaphylaxis.

In one line

• Collapse = mainly a sudden, short-lived hypotensive state, usually with transient cerebral hypoperfusion.
• Shock = a life-threatening systemic perfusion failure with cellular hypoxia and risk of multiorgan failure.

Chapter 4. Endotoxicosis

1. Definition of endotoxicosis

• metabolic products: lactate, urea, creatinine, ammonia;
• products of impaired metabolism: ketones, aldehydes, alcohols;
• inflammatory mediators: cytokines, histamine, bradykinin;
• reactive oxygen species and lipid-peroxidation products;
• activated enzymes: proteases, lysosomal enzymes;
• cellular breakdown products;
• microbial endo- and exotoxins.

• Endotoxemia: elevated concentration of endogenous toxins in the blood.
• Endotoxicosis: the whole pathological process, including toxin production, circulation, tissue damage, compensation, and organ failure.
• Intoxication: the clinical condition at a particular time caused by the action of toxins.

2. Natural defense systems against endogenous toxic substances

A. Intracellular defenses

• Antioxidant system: neutralizes reactive oxygen species.
• Heat-shock proteins: act as chaperones, preserve the correct structure of damaged proteins, and assist protein repair.
• DNA repair enzymes: repair DNA injury.
• Proteasomal and lysosomal systems: remove damaged proteins and cell components.
• Cellular membrane mechanisms: maintain ionic gradients and limit toxin entry.

B. Blood defenses

• Erythrocytes adsorb some toxins on their large membrane surface.
• Albumin binds lipophilic toxins and transports them to detoxifying organs.
• Acute-phase proteins provide:
  • antiprotease protection, for example alpha-1-antitrypsin;
  • antioxidant effects, for example ceruloplasmin and haptoglobin;
  • opsonization of large molecules, for example C-reactive protein and immunoglobulins.

C. Immune defenses

3. Organs of natural detoxification

Intestinal barrier

1. Pre-epithelial: mucus layer and normal microbiota.
2. Epithelial: enterocytes and tight junctions between them.
3. Subepithelial: basement membrane, lamina propria, blood vessels, and local immune system.

Liver detoxification

• Phase I reactions: oxidation, reduction, hydrolysis, mainly via cytochrome P450 enzymes;
• Phase II reactions: conjugation with glucuronic acid, sulfuric acid, glutathione, glycine, etc.;
• Phase III: toxin excretion into bile or blood for renal elimination.

4. Etiology and pathogenesis of endotoxicosis

Causes

• sepsis and severe infection;
• shock;
• severe trauma and burns;
• peritonitis;
• acute pancreatitis;
• ischemia and reperfusion;
• liver failure;
• renal failure and uremia;
• intestinal obstruction and intestinal ischemia;
• malignant tumors;
• metabolic diseases;
• obesity and endocrine disorders;
• radiation injury;
• poisoning by exogenous toxins.

Main pathogenic components

1. Source of toxins
   • inflammatory focus;
   • infected tissue;
   • ischemic or necrotic tissue;
   • damaged cells;
   • intestinal microflora;
   • tissues under hypoxic conditions.
2. Entry and distribution of toxins
   • toxins enter the bloodstream and tissues;
   • endothelial damage and increased permeability facilitate distribution.
3. Failure of barriers and detoxification
   • albumin binding capacity falls;
   • liver and kidneys fail to eliminate toxins;
   • intestinal barrier becomes permeable;
   • toxins accumulate and damage cells.

Types by mechanism of toxin entry

• Production or metabolic: excessive toxin production, for example peritonitis or acute pancreatitis.
• Resorption: absorption of toxins from localized infection, necrosis, abscess, infarction, or phlegmon.
• Reperfusion: washout of toxins and reactive oxygen species from previously ischemic tissues.
• Retention: impaired removal of toxins, especially in hepatic or renal failure.
• Infectious: microbial toxins enter from an infection focus or by bacterial translocation from the intestine.

5. Stages of endotoxicosis

Stage I: Reactive-toxic stage

• A primary injury or inflammatory focus forms.
• Inflammatory mediators, metabolites, cellular breakdown products, and possibly microbial toxins accumulate locally.
• Protective mechanisms are activated.
• Albumin, acute-phase proteins, antioxidants, antiproteases, and phagocytes initially compensate.
• If toxin entry continues, endotoxemia begins.

Stage II: Severe endotoxemia

• Toxin formation exceeds the maximum capacity for detoxification.
• Toxin concentration in blood progressively rises.
• Endothelial activation and injury develop.
• Systemic inflammatory response, hypercoagulation, impaired blood rheology, and acid-base disturbance occur.
• Intestinal barrier injury increases permeability and bacterial translocation.
• The intestine becomes an important additional source of toxins.

Stage III: Decompensation of regulatory systems

• Natural detoxification organs start to fail.
• Liver, kidney, intestinal, and lung dysfunction progresses.
• Biological barriers break down.
• Hypoperfusion, microthrombosis, hypoxia, acidosis, and cell death increase.
• Distress syndromes of the intestine, liver, kidneys, and lungs develop.

Stage IV: Functional multiple organ failure

• Severe failure of circulation and hemostasis occurs.
• Toxin-producing and toxin-eliminating functions of organs are lost.
• The intestine, liver, kidneys, and lungs become both damaged targets and sources of toxins.
• DIC, generalized microcirculatory failure, systemic hypoxia, and multiple organ failure develop.

6. Enteral distress syndrome

Pathogenesis

1. Hypoxia and ischemia damage enterocytes.
2. Sympathetic activation causes splanchnic vasoconstriction.
3. Mucus and bicarbonate secretion decrease.
4. Tight junctions are disrupted, increasing epithelial permeability.
5. Dysbiosis and impaired local immunity develop.
6. Bacteria, endotoxin, and other harmful products pass through the intestinal wall.
7. Intestinal paresis, diarrhea, erosions, and acute ulcers may occur.

7. Hepatic distress syndrome

Consequences of hepatic failure

• reduced toxin biotransformation;
• accumulation of lipophilic toxins;
• impaired urea synthesis causing hyperammonemia;
• impaired protein synthesis causing hypoalbuminemia;
• reduced antiprotease and acute-phase protein production;
• impaired bile formation and toxin excretion;
• coagulopathy due to reduced clotting-factor synthesis.

Kidney and lung involvement

• Kidneys: tubular degeneration, reduced filtration, acute tubular necrosis, retention azotemia, uremia, water-electrolyte and acid-base disorders.
• Lungs: alveolar-capillary membrane damage, inflammation, pulmonary edema, and ARDS.
• Pancreas: circulating pancreatic enzymes and inflammatory mediators can cause systemic endothelial injury, DIC, and multiorgan failure.

8. Diagnosis of endotoxicosis

A. Immunological indicators

• Complete blood count and leukocyte differential.
• Leukocyte intoxication index.
• Changes in neutrophil, lymphocyte, and monocyte ratios.
• Inflammatory markers such as CRP and procalcitonin where infection is suspected.

B. Biochemical indicators

• Lactate.
• Urea and creatinine.
• Bilirubin and liver enzymes.
• Electrolytes and blood gases.
• Ammonia.
• Alpha-amylase in pancreatitis.
• Coagulation tests.
• Molecules of medium mass.
• Lipid-peroxidation products, including malondialdehyde.
• Free fatty acids and lysophospholipids.
• Albumin concentration and effective albumin concentration.

C. Albumin toxicity measurements

• Toxicity index:

• A higher value suggests a greater burden of albumin-bound toxins.
• Coefficient of endogenous intoxication:

D. Clinical and integral indicators

• fever or hypothermia;
• tachycardia and hypotension;
• reduced urine output;
• altered mental state;
• metabolic acidosis;
• hypoxemia;
• coagulopathy;
• evidence of liver, kidney, lung, or intestinal dysfunction.

Chapter 5. Metabolic Syndrome: Viva Answers

1. What is metabolic syndrome?

1. Abdominal or visceral obesity
2. Insulin resistance with hyperinsulinemia
3. Impaired glucose tolerance or type 2 diabetes mellitus
4. Atherogenic dyslipidemia
5. Arterial hypertension

“Metabolic syndrome is a combination of central obesity, insulin resistance, hyperglycemia, dyslipidemia, and hypertension, which together increase cardiovascular risk.”

2. Explain insulin resistance as the main link in metabolic syndrome.

Causes of insulin resistance

• Genetic predisposition
• Visceral obesity
• Physical inactivity
• High-calorie diet
• Excess free fatty acids
• Inflammatory cytokines, especially TNF-alpha and IL-6
• Reduced number or impaired function of insulin receptors
• Post-receptor signaling defects
• Reduced GLUT-4 transporters in muscle and adipose tissue
• Excess glucocorticoids

Main consequences

• Reduced GLUT-4-mediated glucose uptake.
• Reduced glycogen synthesis.
• Hyperglycemia develops.

• Insulin fails to suppress gluconeogenesis and glycogenolysis.
• The liver produces excess glucose.
• Free fatty acids increase triglyceride and VLDL synthesis.

• Insulin cannot adequately inhibit lipolysis.
• Free fatty acids enter the portal circulation.
• These free fatty acids worsen hepatic insulin resistance and dyslipidemia.

“Insulin resistance causes compensatory hyperinsulinemia, hyperglycemia, increased lipolysis, increased free fatty acids, dyslipidemia, sodium retention, sympathetic activation, and hypertension.”

3. Explain obesity as the main link in metabolic syndrome.

• greater blood supply and innervation;
• more adrenergic and glucocorticoid receptors;
• relatively fewer insulin receptors;
• high sensitivity to catecholamine-induced lipolysis;
• direct drainage of free fatty acids into the portal circulation.

Why is visceral obesity harmful?

• hepatic insulin resistance;
• increased gluconeogenesis;
• increased triglyceride and VLDL formation;
• fatty liver;
• atherogenic dyslipidemia.

“Visceral obesity is the key clinical link in metabolic syndrome because it releases free fatty acids and proinflammatory adipokines, causing insulin resistance, dyslipidemia, hypertension, endothelial dysfunction, and thrombosis.”

4. How does metabolic syndrome cause arterial hypertension?

Mechanisms

1. Activation of sympathetic nervous system
   • Hyperinsulinemia and leptin increase sympathetic activity.
   • This causes vasoconstriction, increased heart rate, and increased peripheral vascular resistance.
2. Activation of RAAS
   • Adipose tissue contains RAAS components and produces angiotensinogen.
   • Angiotensin II causes vasoconstriction.
   • Aldosterone causes sodium and water retention.
3. Renal sodium retention
   • Insulin promotes sodium reabsorption in renal tubules.
   • Increased blood volume raises blood pressure.
4. Endothelial dysfunction
   • Reduced nitric oxide production decreases vasodilation.
   • Increased endothelin-1 promotes vasoconstriction.
5. Obstructive sleep apnea
   • Common in obesity.
   • Recurrent hypoxia activates the sympathetic nervous system and worsens hypertension.

“In metabolic syndrome, hypertension occurs due to sympathetic and RAAS activation, hyperinsulinemia-induced sodium retention, hyperleptinemia, endothelial dysfunction, and often sleep apnea.”

5. Explain dyslipidemia in metabolic syndrome.

Main features

• Increased triglycerides
• Increased VLDL
• Increased small dense LDL particles
• Decreased HDL cholesterol

Pathogenesis

1. Insulin resistance causes increased lipolysis in visceral fat.
2. Free fatty acids enter the liver.
3. The liver synthesizes more triglycerides and VLDL.
4. Insulin resistance reduces lipoprotein lipase activity, so triglyceride-rich lipoproteins are not cleared properly.
5. Hepatic lipase converts LDL into small, dense LDL particles.
6. HDL becomes triglyceride-rich and is cleared faster, so HDL concentration falls.

Why are small dense LDL particles dangerous?

• enter the arterial wall more easily;
• are more easily oxidized;
• are taken up by macrophages;
• promote foam-cell formation;
• accelerate atherosclerosis.

“Dyslipidemia in metabolic syndrome consists of high triglycerides, high VLDL, low HDL, and small dense LDL. It develops mainly because free fatty acids from visceral adipose tissue increase hepatic VLDL synthesis.”

6. Explain impaired glucose metabolism in metabolic syndrome.

Sequence

1. Visceral obesity increases free fatty acids and cytokines.
2. Free fatty acids impair insulin signaling in muscle, liver, and adipose tissue.
3. Muscle glucose uptake decreases.
4. The liver continues gluconeogenesis and glycogenolysis despite insulin.
5. Blood glucose rises.
6. The pancreas compensates by releasing more insulin.
7. Over time, beta cells develop dysfunction due to glucotoxicity, lipotoxicity, inflammation, and oxidative stress.
8. Impaired fasting glucose, impaired glucose tolerance, and finally type 2 diabetes mellitus develop.

Levels of insulin resistance

• Pre-receptor: abnormal insulin formation, for example defective conversion of proinsulin to insulin.
• Receptor: reduced number or altered function of insulin receptors.
• Post-receptor: impaired intracellular signaling and impaired GLUT-4 glucose transport.

“Impaired glucose metabolism in metabolic syndrome is caused by insulin resistance in liver, muscle, and adipose tissue, followed by progressive beta-cell dysfunction. This produces impaired glucose tolerance and may progress to type 2 diabetes mellitus.”

High-yield summary for viva

“Metabolic syndrome is a cluster of abdominal obesity, insulin resistance, dyslipidemia, hypertension, and impaired glucose metabolism. Visceral obesity releases free fatty acids and inflammatory adipokines. These produce insulin resistance, hyperinsulinemia, hepatic VLDL production, endothelial dysfunction, sodium retention, sympathetic activation, and RAAS activation. Therefore, metabolic syndrome increases the risk of type 2 diabetes and atherosclerotic cardiovascular disease.”

Chapter 6. Acute Respiratory Distress Syndrome: Viva-Style Answers

1. What is acute respiratory distress syndrome?

“ARDS is not cardiogenic pulmonary edema. It results from inflammatory damage to the alveolar epithelium and pulmonary capillary endothelium.”

2. What are the main causes of ARDS?

A. Direct pulmonary causes

• Viral or bacterial pneumonia
• Aspiration of gastric contents
• Inhalation of toxic gases or smoke
• Pulmonary contusion
• Near drowning
• Severe pulmonary infection
• Fat embolism
• Ventilator-induced lung injury

B. Indirect extrapulmonary causes

• Sepsis, especially septic shock
• Severe trauma or polytrauma
• Massive blood loss and shock
• Acute pancreatitis
• Extensive burns
• Massive transfusion or transfusion-related lung injury
• Severe non-pulmonary infection
• Ischemia-reperfusion injury

“The most common causes of ARDS are sepsis, severe pneumonia, aspiration, trauma, burns, and acute pancreatitis. Causes may directly injure the lung or indirectly cause systemic inflammation and secondary lung damage.”

3. Explain the pathogenesis of ARDS.

Sequence of events

1. A direct or indirect damaging factor activates macrophages, endothelial cells, and epithelial cells.
2. These cells release inflammatory mediators, including TNF-alpha, IL-1, IL-6, IL-8, chemokines, and reactive oxygen species.
3. Neutrophils migrate into pulmonary capillaries, interstitium, and alveoli.
4. Activated neutrophils release proteases, oxidants, cytokines, and neutrophil extracellular traps.
5. Endothelial and epithelial intercellular junctions are disrupted.
6. Permeability of the alveolar-capillary barrier rises.
7. Protein-rich fluid enters the interstitium and then the alveoli.
8. Alveolar edema develops.
9. Surfactant is damaged and inactivated.
10. Alveoli collapse, called atelectasis.
11. Ventilation-perfusion mismatch and intrapulmonary right-to-left shunting occur.
12. Severe hypoxemia and reduced lung compliance develop.

“ARDS develops because inflammatory mediators and activated neutrophils damage the alveolar epithelium and capillary endothelium. This increases permeability of the blood-air barrier, causing protein-rich non-cardiogenic alveolar edema, surfactant dysfunction, atelectasis, shunting, severe hypoxemia, and respiratory failure.”

4. What is the role of neutrophils in ARDS?

• reactive oxygen species;
• proteolytic enzymes;
• cytokines;
• phospholipases;
• neutrophil extracellular traps.

• pulmonary vascular endothelium;
• alveolar epithelial cells;
• basement membranes;
• surfactant phospholipids.

“Neutrophils damage the blood-air barrier by releasing oxidants, proteases, cytokines, and extracellular traps. This causes endothelial and epithelial injury, capillary leakage, alveolar edema, and impaired gas exchange.”

5. What happens to surfactant in ARDS?

Mechanisms

• Damage to type II alveolocytes reduces surfactant synthesis.
• Plasma proteins entering alveoli bind surfactant phospholipids and inactivate them.
• Neutrophil proteases, phospholipases, and reactive oxygen species damage surfactant.
• Inflammatory edema dilutes and disrupts surfactant.

Consequences

• Surface tension in alveoli increases.
• Small alveoli collapse during expiration.
• Atelectasis develops.
• Lung compliance decreases, meaning the lungs become stiff.
• Work of breathing increases.
• More lung tissue is excluded from gas exchange.
• Hypoxemia worsens.

“In ARDS, surfactant is reduced and inactivated by edema proteins and inflammatory mediators. Surface tension rises, alveoli collapse, lung compliance decreases, and hypoxemia becomes more severe.”

6. What are the stages of ARDS?

7. Describe the exudative stage of ARDS.

Main features

• Neutrophil-mediated inflammation
• Endothelial dysfunction
• Damage to alveolar epithelial cells
• Increased pulmonary capillary permeability
• Interstitial and alveolar edema
• Protein-rich fluid in alveoli
• Surfactant dysfunction
• Alveolar collapse
• Hypoxemia and reduced lung compliance
• Formation of hyaline membranes

“The exudative stage is the acute inflammatory stage. Neutrophils damage the alveolar-capillary barrier, causing protein-rich edema, surfactant dysfunction, atelectasis, hyaline membranes, shunting, and severe hypoxemia.”

8. Describe the fibroproliferative stage of ARDS.

Main processes

• Neutrophil activity decreases.
• Inflammatory mediators decrease.
• Type II alveolocytes proliferate.
• Type II pneumocytes differentiate into type I alveolocytes.
• Epithelial tight junctions and the blood-air barrier are restored.
• Alveolar edema fluid is reabsorbed.
• Fibroblasts and new blood vessels may proliferate.

• epithelial sodium channels, ENaC;
• chloride channels, including CFTR;
• aquaporins.

“The fibroproliferative stage is the stage of repair. Type II pneumocytes proliferate, alveolar epithelium regenerates, edema fluid is cleared, and the blood-air barrier is restored. Excess fibroblast activity may lead to pulmonary fibrosis.”

9. Describe the fibrotic stage of ARDS.

Mechanisms

• Excessive activation of fibroblasts and myofibroblasts
• Excess production of collagen and extracellular matrix
• Increased profibrotic factors and reduced antifibrotic activity
• Persistent fibrin deposition in alveoli
• Microvascular thrombosis and vascular remodeling

Consequences

• Thickened alveolar septa
• Pulmonary fibrosis
• Reduced lung compliance
• Persistent diffusion impairment
• Pulmonary hypertension
• Long-term respiratory dysfunction

“The fibrotic stage is characterized by excessive collagen deposition and remodeling of lung tissue. It causes stiff lungs, thickened alveolar septa, persistent hypoxemia, reduced diffusion capacity, and possible pulmonary hypertension.”

10. What are the morphological changes in ARDS?

Early exudative stage

• Interstitial and alveolar edema
• Congestion of capillaries
• Neutrophil infiltration
• Necrosis of alveolar epithelial and endothelial cells
• Alveolar hemorrhages
• Hyaline membranes lining alveoli and alveolar ducts
• Collapse of alveoli

Late fibrotic stage

• Proliferation of type II pneumocytes
• Fibroblast and myofibroblast proliferation
• Thickened interalveolar septa
• Collagen deposition
• Fibrosing alveolitis
• Pulmonary-vessel sclerosis and partial obliteration of vessel lumen

“The morphological basis of ARDS is diffuse alveolar damage. Early ARDS shows edema, neutrophils, epithelial necrosis, hemorrhage, and hyaline membranes. Late ARDS shows interstitial fibrosis, thickened septa, and vascular remodeling.”

One-minute answer for professor

“ARDS is an acute diffuse inflammatory lung injury causing non-cardiogenic pulmonary edema and severe hypoxemic respiratory failure. It may result from direct lung injury, such as pneumonia or aspiration, or indirect injury, such as sepsis, trauma, burns, or pancreatitis. Inflammatory mediators recruit neutrophils, which damage the alveolar epithelium and capillary endothelium. Increased permeability causes protein-rich edema, surfactant inactivation, atelectasis, shunting, and reduced lung compliance. ARDS progresses through exudative, fibroproliferative, and sometimes fibrotic stages. The morphological basis is diffuse alveolar damage with hyaline membranes in the early stage and fibrosis in the late stage.”

Chapter 7. Multiple Organ Failure: Viva-Style Answers

1. What is multiple organ failure?

“MOF is a syndrome of progressive dysfunction of two or more organs caused by severe injury, shock, sepsis, or systemic inflammation. It develops due to impaired tissue perfusion, endothelial damage, inflammation, and microcirculatory failure.”

2. What are the main causes of MOF?

Main causes

• Severe trauma and polytrauma
• Hemorrhagic shock
• Septic shock and severe infection
• Extensive burns
• Acute pancreatitis
• Severe acute respiratory distress syndrome
• Major surgery or complications of resuscitation
• Massive blood transfusion or hemolytic transfusion reaction
• Anaphylactic shock
• Crush syndrome
• Intestinal ischemia or reperfusion injury
• Poisoning and severe metabolic disorders
• Amniotic-fluid embolism

“The most common causes of MOF are sepsis, shock, major trauma, burns, acute pancreatitis, and massive blood loss. All these conditions can cause systemic inflammation, hypoxia, endothelial injury, and microcirculatory disorders.”

3. Which organ systems are commonly affected in MOF?

“The lungs, kidneys, cardiovascular system, liver, brain, and hematologic system are mainly affected. The lungs often develop ARDS, kidneys develop acute injury, and the hematologic system may develop DIC.”

4. How is MOF diagnosed and assessed?

• SOFA: Sequential Organ Failure Assessment
• qSOFA: quick SOFA screening tool
• APACHE II/III: Acute Physiology and Chronic Health Evaluation
• SAPS: Simplified Acute Physiology Score

1. Respiratory: PaO₂/FiO₂ ratio
2. Coagulation: platelet count
3. Liver: bilirubin
4. Cardiovascular: blood pressure and vasopressor requirement
5. Central nervous system: Glasgow Coma Scale
6. Renal: creatinine level and urine output

“MOF is assessed by evidence of dysfunction in two or more organs. The most commonly used clinical score is SOFA, which evaluates respiratory, cardiovascular, coagulation, liver, CNS, and renal function.”

5. What is the difference between primary and secondary MOF?

Primary or early MOF

• Develops within the first 72 hours after severe injury.
• Caused directly by the original damaging factor.
• Main mechanism: severe systemic and microcirculatory hypoperfusion with hypoxic-ischemic cell injury.
• Typical examples:
  • severe trauma;
  • massive hemorrhage;
  • severe burns;
  • fulminant septic shock;
  • anaphylactic shock;
  • crush syndrome.

Secondary or delayed MOF

• Develops after a latent period, often after several days or around one week.
• Caused by dysregulated systemic inflammation, infection, immune dysfunction, and secondary complications.
• Typical example: sepsis developing after trauma, surgery, burns, or prolonged critical illness.

“Primary MOF occurs early, within 72 hours, due to direct hypoperfusion and ischemic injury from the initial insult. Secondary MOF develops later due to systemic inflammation, sepsis, immune dysregulation, and secondary infection.”

6. What is the basic mechanism of early MOF?

Sequence

1. Shock, blood loss, or cardiac dysfunction reduces systemic blood flow.
2. Oxygen delivery to vital organs decreases.
3. Tissue hypoxia develops.
4. Anaerobic glycolysis causes lactate accumulation and metabolic acidosis.
5. ATP synthesis falls.
6. Ion pumps fail, especially Na⁺/K⁺-ATPase.
7. Cells swell, calcium enters cells, and mitochondrial dysfunction develops.
8. Reactive oxygen species, proteases, and lysosomal enzymes cause membrane damage.
9. Cells die by necrosis or apoptosis.
10. Organ dysfunction develops.

“Early MOF is mainly caused by generalized tissue hypoperfusion. Hypoxia causes ATP depletion, acidosis, mitochondrial dysfunction, membrane damage, and cell death. Reperfusion can add oxidative injury.”

7. Explain the mechanism of secondary MOF.

Main mechanisms

• Systemic inflammatory response with excess cytokines
• Endothelial activation and injury
• Increased capillary permeability
• Neutrophil activation and release of proteases and reactive oxygen species
• Microvascular thrombosis and DIC
• Intestinal-barrier failure and bacterial translocation
• Endotoxemia
• Compensatory anti-inflammatory response syndrome, CARS
• Immunosuppression and secondary infection

“Secondary MOF occurs because systemic inflammation becomes uncontrolled. Cytokines, endothelial damage, capillary leakage, microthrombosis, endotoxemia, and later immunosuppression cause progressive dysfunction of multiple organs.”

8. What is the role of endothelium in MOF?

• vascular tone becomes abnormal;
• vasodilation may cause hypotension;
• permeability rises, causing edema and hypovolemia;
• leukocytes adhere to endothelium and enter tissues;
• procoagulant activity increases;
• microthrombi form;
• tissue perfusion decreases.

“Endothelial damage causes capillary leak, edema, disturbed vascular tone, leukocyte adhesion, and microthrombosis. Therefore, it is a central mechanism of systemic microcirculatory failure in MOF.”

9. What is the role of the intestine in MOF?

Consequences

• loss of tight junction integrity;
• increased intestinal permeability;
• bacterial translocation;
• entry of endotoxin and microbial products into blood;
• cytokine release;
• systemic inflammation and endotoxemia;
• further injury to the liver, lungs, kidneys, and other organs.

“During shock, intestinal hypoperfusion damages the mucosal barrier. Bacteria and endotoxins translocate into the blood, causing endotoxemia and systemic inflammation, which aggravate MOF.”

10. What is the role of coagulation disorders in MOF?

Effects of DIC

• widespread microthrombi block capillaries;
• tissue ischemia and organ injury worsen;
• platelets and clotting factors are consumed;
• bleeding may occur simultaneously;
• impaired microcirculation perpetuates MOF.

“In MOF, endothelial injury and inflammation activate coagulation. Microthrombi reduce tissue perfusion, while consumption of platelets and clotting factors can cause bleeding. This is the basis of DIC.”

11. What are the consequences and prognosis of MOF?

• severity of the initial disease;
• number of organs involved;
• duration of dysfunction;
• patient age;
• comorbidities;
• presence of sepsis or DIC;
• response to resuscitation and source control.

“MOF is dangerous because it may progress to irreversible organ failure and death. Prognosis worsens as the number of failed organs increases, especially with sepsis, DIC, persistent hypotension, and respiratory or renal failure.”

One-minute answer for professor

“Multiple organ failure is progressive dysfunction of two or more organs in a critically ill patient, so that homeostasis cannot be maintained without support. It occurs in sepsis, shock, trauma, burns, pancreatitis, and major surgery. Primary MOF occurs within 72 hours due to direct tissue hypoperfusion and ischemia. Secondary MOF occurs later due to systemic inflammation, endothelial injury, capillary leak, microthrombosis, endotoxemia, and immune dysregulation. The lungs, kidneys, heart, liver, brain, and coagulation system are commonly affected. The main assessment tool is SOFA, which evaluates respiratory, cardiovascular, coagulation, hepatic, neurological, and renal function.”

Chapter 8. Chronic Pain: Viva-Style Answers

1. What is the nociceptive system?

• A-delta fibers: thinly myelinated fibers transmitting fast, sharp, well-localized pain.
• C fibers: unmyelinated fibers transmitting slow, dull, burning, poorly localized pain.

“The nociceptive system detects harmful mechanical, thermal, and chemical stimuli. It includes nociceptors, peripheral sensory fibers, spinal pathways, thalamus, cortex, and limbic structures that produce the sensory and emotional components of pain.”

2. What are nociceptors?

• mechanical injury;
• extreme heat or cold;
• inflammation;
• ischemia;
• chemical mediators released from damaged tissues.

“Nociceptors are free nerve endings of A-delta and C fibers. They detect harmful stimuli and initiate pain impulses. Silent nociceptors become sensitive mainly during inflammation.”

3. What are algogens and what is their role?

Important algogens

• Bradykinin
• Prostaglandins
• Histamine
• Serotonin
• ATP
• Hydrogen ions
• Potassium ions
• Cytokines such as TNF-alpha and IL-1
• Leukotrienes
• Endothelin
• Substance P
• Calcitonin gene-related peptide
• Nerve growth factor

“Algogens are pain-producing chemicals released during tissue damage and inflammation. They activate nociceptors and lower their pain threshold, causing peripheral sensitization and hyperalgesia.”

4. Describe the neurochemical mechanisms of nociception.

• glutamate;
• substance P;
• neurokinin A;
• calcitonin gene-related peptide.

“Nociception begins when algogens activate nociceptors. Pain impulses travel by A-delta and C fibers to the dorsal horn, where glutamate and substance P transmit the signal to ascending pathways and the brain.”

5. What is the antinociceptive system?

• periaqueductal gray matter;
• raphe nuclei;
• pons and medullary reticular formation;
• thalamic nuclei;
• descending pathways to the dorsal horn of the spinal cord.

• endogenous opioids: endorphins and enkephalins;
• serotonin;
• norepinephrine;
• GABA;
• cannabinoids;
• acetylcholine.

“The antinociceptive system is the descending inhibitory system that reduces pain transmission in the dorsal horn and brain. Its major mediators are endogenous opioids, serotonin, norepinephrine, GABA, and cannabinoids.”

6. What are the main types of pain?

“Pain is classified as nociceptive, neuropathic, and nociplastic or dysfunctional. Chronic pain is often mixed, so treatment must be based on the dominant mechanism.”

7. Explain nociceptive pain.

Types

• Somatic pain
  • Arises from skin, muscle, joints, or bone.
  • Usually well localized.
  • May be sharp or aching.
• Visceral pain
  • Arises from internal organs.
  • Usually deep, diffuse, cramping, or poorly localized.
  • Often transmitted by C fibers.
  • May be associated with referred pain.

Hyperalgesia

• Primary hyperalgesia occurs at the site of injury because of peripheral sensitization.
• Secondary hyperalgesia occurs in surrounding normal tissue because of central sensitization.

“Nociceptive pain is caused by tissue injury or inflammation. Primary hyperalgesia is due to peripheral sensitization at the injured site, while secondary hyperalgesia is due to central sensitization in the spinal cord and brain.”

8. Explain neuropathic pain.

Pathogenesis

• increased sodium-channel expression;
• hyperexcitability of damaged nerve fibers;
• ectopic generation of impulses;
• abnormal cross-talk between nerve fibers;
• sensitization of dorsal horn, thalamic, and cortical neurons;
• loss of inhibitory interneurons;
• maladaptive neuroplastic changes.

Clinical features

• burning pain;
• shooting or electric-shock-like pain;
• tingling;
• pins-and-needles sensation;
• numbness;
• allodynia;
• hyperalgesia;
• dysesthesia;
• paresthesia.

• Allodynia: pain due to a normally non-painful stimulus, such as light touch.
• Hyperalgesia: excessive pain response to a painful stimulus.
• Paresthesia: abnormal spontaneous sensation, such as tingling.
• Dysesthesia: unpleasant abnormal sensation, spontaneous or evoked.

“Neuropathic pain results from damage to the somatosensory nervous system. It is caused by ectopic impulses, increased sodium channels, loss of inhibition, and central sensitization. It commonly presents as burning, electric-shock-like pain, allodynia, and paresthesia.”

9. What is dysfunctional or nociplastic pain?

• fibromyalgia;
• migraine;
• irritable bowel syndrome;
• functional biliary pain;
• persistent idiopathic facial pain;
• complex regional pain syndrome.

• fatigue;
• sleep disturbance;
• anxiety or depression;
• increased sensitivity to light, sound, touch, or temperature;
• impaired stress adaptation.

“Nociplastic pain is caused by abnormal pain processing rather than clear tissue injury or nerve damage. Its main mechanism is central sensitization. Fibromyalgia and migraine are common examples.”

10. What is central sensitization?

Mechanism

• prolonged glutamate and substance P release;
• activation of NMDA receptors;
• increased calcium entry into neurons;
• activation of glial cells;
• cytokine and prostaglandin release;
• reduced inhibitory control;
• structural and functional neuroplastic changes.

Result

• hyperalgesia;
• allodynia;
• spread of pain beyond the original lesion;
• persistent pain even after tissue healing.

“Central sensitization is hyperexcitability of spinal and brain pain pathways. It is caused by persistent nociceptive input and causes hyperalgesia, allodynia, spreading of pain, and pain persistence after healing.”

11. Explain the mechanisms of chronic pain.

Vicious circle of chronic pain

1. Tissue injury or nerve injury causes pain.
2. Persistent pain impulses cause peripheral and central sensitization.
3. Pain increases stress, anxiety, poor sleep, and reduced physical activity.
4. These factors further increase central excitability and reduce pain inhibition.
5. Chronic pain becomes self-maintaining.

“Chronic pain develops because persistent nociceptive or neuropathic input produces peripheral and central sensitization. Sleep disturbance, stress, anxiety, depression, and reduced activity perpetuate a vicious cycle of pain.”

12. What are the principles of chronic pain treatment?

Main principles

1. Treat the underlying cause
   • Control inflammation, infection, tumor, ischemia, or structural disease.
2. Suppress algogen formation
   • Nonsteroidal anti-inflammatory drugs and non-opioid analgesics when appropriate.
3. Reduce nociceptive impulse transmission
   • Local anesthetics and nerve blocks in selected cases.
4. Activate descending antinociceptive pathways
   • Some antidepressants increase serotonin and norepinephrine-mediated inhibition.
5. Treat neuropathic mechanisms
   • Anticonvulsant medicines and selected antidepressants may reduce ectopic neuronal activity and central sensitization.
6. Treat muscle spasm
   • Physiotherapy, exercise, and selected muscle-relaxing treatments.
7. Use non-drug therapy
   • Exercise therapy, physiotherapy, cognitive-behavioral therapy, relaxation, mindfulness, and selected neuromodulation approaches.
8. Optimize psychological and social function
   • Address sleep, mood, work function, fear-avoidance behavior, and coping strategies.

“Chronic-pain treatment is multimodal. We treat the cause, reduce inflammation and nociceptive input, control neuropathic mechanisms, improve physical function, and address sleep, mood, and maladaptive pain behavior.”

13. Which drugs activate the antinociceptive system?

• Opioid analgesics
  • Activate opioid receptors and imitate endogenous opioid analgesia.
  • Used selectively because tolerance, dependence, respiratory depression, and overdose are important risks.
• Antidepressants
  • Especially those increasing serotonin and norepinephrine transmission.
  • They strengthen descending inhibitory pain pathways.
  • Useful particularly in chronic neuropathic pain and some nociplastic pain conditions.

“Opioids activate opioid receptors, while antidepressants enhance serotonergic and noradrenergic descending inhibition. Their use depends on pain mechanism and individual risk.”

14. Which agents reduce ectopic impulses and central sensitization?

• local anesthetic techniques for selected conditions;
• NMDA-receptor modulation in specialist settings;
• treatment of muscle spasm with centrally acting muscle relaxants or local botulinum toxin in selected patients.

“Anticonvulsants are used for neuropathic pain because they reduce ectopic discharges in damaged nerves and decrease central neuronal hyperexcitability.”

15. What are non-drug methods for chronic-pain treatment?

• graded exercise and physiotherapy;
• cognitive-behavioral therapy;
• education about pain mechanisms;
• relaxation and mindfulness;
• sleep improvement;
• acupuncture or electroacupuncture;
• transcutaneous electrical nerve stimulation;
• rehabilitation and functional restoration;
• occupational therapy;
• biofeedback;
• support for return to daily activities and work.

“Non-drug treatment aims to improve physical function, reduce fear and stress, restore activity, and strengthen endogenous pain-control mechanisms. Exercise therapy and cognitive-behavioral approaches are central methods.”

One-minute answer for professor

“Chronic pain is pain lasting more than three months or beyond normal healing. The nociceptive system includes nociceptors, A-delta and C fibers, spinal pathways, thalamus, cortex, and limbic structures. Pain may be nociceptive, neuropathic, or nociplastic. Nociceptive pain results from tissue injury, neuropathic pain results from somatosensory nerve damage, and nociplastic pain results from altered pain processing. Persistent pain causes peripheral and central sensitization, leading to hyperalgesia and allodynia. Treatment is multimodal and includes treating the underlying cause, analgesics, neuropathic-pain medicines, physical rehabilitation, psychological therapy, and restoration of function.”

• Left-side cue questions for active recall
• Right-side concise viva answers
• A 30-second bottom summary for each chapter
• Easy memory hooks