TEST BANK
PATHOPHYSIOLOGY FOR ADVANCED PRACTICE
,Table of Contents
PART I: Foundational Physiologic Concepts
Unit I: The Cell
1. Cellular Biology, Regulation, and Control Mechanisms
2. Cellular and Tissue Physiology
3. Bioenergetics and Body Metabolism
4. Body Fluid Homeostasis
Unit II: Genetics and Genomics
5. Basic Genetics
6. Patterns of Inheritance, Mitochondrial Inheritance, Epigenetics, and Selected Associated
Disorders
Unit III: Inflammation, Immunity, Infection, and Cancer Biology
7. Innate Immunity and Inflammation
8. Adaptive Immunity
9. Infectious Processes and Body Responses
10. Abnormal Cell Growth and Cancer Biology
PART II: Pathophysiology of Disorders Within Specific Body Systems
Section: Oxygenation and Perfusion
Unit IV: Cardiovascular System
11. Review of Cardiovascular Development, Structure, and Function
12. Vascular Disorders
13. Cardiac Disorders
14. Congenital Heart Disease Across the Lifespan
, 15. Shock and Multiple Organ Dysfunction Syndrome
Unit V: Pulmonary System
16. Review of Pulmonary Structure, Development, and Function
17. Congenital, Obstructive, and Restrictive Pulmonary Disorders
18. Infectious Pulmonary Disorders and Lung Cancer
Unit VI: Renal-Urinary System
19. Review of Renal System Structure, Development, and Function
20. Urinary Tract Disorders
21. Kidney Disorders
Unit VII: Hematologic and Lymphatic System
22. Review of Hematologic System Development, Structure, and Function
23. Hematologic and Lymphatic System Disorders
Section: Sensation, Mobility, and Regulation
Unit VIII: Nervous System
24. Review of Nervous System Development, Structure, and Function
25. Central Nervous System Disorders
26. Peripheral Nervous System Disorders
27. Disorders of the Special Senses
28. Mental Health Disorders
Unit IX: Musculoskeletal System
29. Review of Musculoskeletal Development, Structure, and Function
30. Muscle and Tendon Disorders
31. Bone and Joint Disorders
Unit X: Endocrine System
, 32. Review of Endocrine Structure, Function, and Interactions
33. Disorders of the Hypothalamus, Pituitary Glands, and Adrenal Glands
34. Disorders of the Thyroid Gland and Parathyroid Glands
35. Glycemic Control and Diabetes Mellitus
Section: Protection, Nutrition, and Reproduction
Unit XI: Disorders of Immunity
36. Disorders of Reduced Immune Function
37. Hypersensitivity and Autoimmune Disorders
Unit XII: Integumentary System
38. Review of Integumentary Development, Structure, and Function
39. Integumentary System Disorders
Unit XIII: Digestive System
40. Review of Gastrointestinal Development, Structure, and Function
41. Disorders of the Mouth, Throat, Esophagus, and Stomach
42. Disorders of the Small Intestine, Large Intestine, Pancreas, and Hepatobiliary System
Unit XIV: Reproductive Systems
43. Review of Reproductive System Development, Structure, Function, and Sex Chromosome
Abnormalities
44. Common Disorders of the Female Reproductive System
45. Male Reproductive Disorders
46. Sexually Transmitted Infections
47. Physiology and Pathophysiology of the Breast
,PART I: Foundational Physiologic Concepts
CHAPTER 1: Cellular Biology, Regulation, and Control Mechanisms
EASY QUESTIONS (1-5)
1. Which organelle is primarily responsible for ATP production in the cell?
A) Nucleus
B) Mitochondria
C) Ribosome
D) Golgi apparatus
ANSWER: B) Mitochondria
Rationale: Mitochondria are the "powerhouses" of the cell, responsible for producing ATP through
oxidative phosphorylation and the citric acid cycle. The nucleus contains genetic material, ribosomes
synthesize proteins, and the Golgi apparatus packages and modifies proteins. Understanding cellular
energy production is fundamental to comprehending cellular dysfunction in disease states.
2. The primary function of the endoplasmic reticulum (ER) is:
A) DNA replication
B) Protein synthesis and lipid metabolism
C) Waste elimination
D) Cell division
ANSWER: B) Protein synthesis and lipid metabolism
Rationale: The rough ER synthesizes proteins (due to attached ribosomes), while the smooth ER is
involved in lipid synthesis, detoxification, and calcium storage. DNA replication occurs in the nucleus,
waste elimination involves lysosomes and cellular transport mechanisms, and cell division involves the
nucleus and cytoskeleton. ER dysfunction is implicated in various pathologic conditions including ER
stress responses.
3. Which type of cellular junction allows for direct communication between adjacent cells?
, A) Tight junctions
B) Desmosomes
C) Gap junctions
D) Adherens junctions
ANSWER: C) Gap junctions
Rationale: Gap junctions contain connexon channels that allow small molecules and ions to pass directly
between adjacent cells, enabling electrical and metabolic coupling. Tight junctions seal spaces between
cells, desmosomes provide mechanical strength, and adherens junctions connect actin filaments
between cells. Gap junction dysfunction can lead to cardiac arrhythmias and other pathologic states.
4. The cell membrane is primarily composed of:
A) Carbohydrates only
B) Phospholipid bilayer with embedded proteins
C) Pure cholesterol
D) Nucleic acids
ANSWER: B) Phospholipid bilayer with embedded proteins
Rationale: The cell membrane consists of a phospholipid bilayer with hydrophilic heads facing outward
and hydrophobic tails facing inward, embedded with proteins that serve as receptors, channels, and
transporters. Cholesterol is present but not the primary component, and carbohydrates form glycocalyx
on the surface. Understanding membrane structure is essential for comprehending drug transport and
cellular signaling.
5. Apoptosis is best described as:
A) Accidental cell death due to injury
B) Programmed cell death
C) Cellular division
D) Cellular hypertrophy
ANSWER: B) Programmed cell death
,Rationale: Apoptosis is controlled, programmed cell death that is essential for normal development and
tissue homeostasis. It differs from necrosis (accidental death from injury), which causes inflammation.
Apoptosis involves caspase activation, DNA fragmentation, and phagocytosis without inflammatory
response. Dysregulated apoptosis contributes to cancer (too little) or degenerative diseases (too much).
MEDIUM QUESTIONS (6-10)
6. G-protein coupled receptors (GPCRs) function by:
A) Directly opening ion channels
B) Activating intracellular second messenger cascades
C) Transporting molecules across membranes
D) Binding directly to DNA
ANSWER: B) Activating intracellular second messenger cascades
Rationale: GPCRs are transmembrane receptors that, when activated by ligand binding, activate G-
proteins which then trigger second messenger systems (cAMP, IP3, DAG, calcium). This amplifies signals
and allows for complex regulation. GPCRs are targets for approximately 30-40% of therapeutic drugs.
They don't directly open channels (that's ligand-gated channels) or bind DNA (that's nuclear receptors).
7. Which cellular adaptation involves an increase in cell size without an increase in cell number?
A) Hyperplasia
B) Hypertrophy
C) Metaplasia
D) Dysplasia
ANSWER: B) Hypertrophy
Rationale: Hypertrophy is increased cell size, often in response to increased workload (e.g., cardiac
muscle in hypertension). Hyperplasia is increased cell number, metaplasia is replacement of one cell
type with another, and dysplasia is disordered cell growth. Some tissues can undergo both hypertrophy
and hyperplasia (e.g., uterus during pregnancy), while permanent cells like cardiac myocytes can only
hypertrophy.
,8. The Na+/K+-ATPase pump maintains cellular homeostasis by:
A) Moving 3 Na+ out and 2 K+ in, using ATP
B) Moving 2 Na+ out and 3 K+ in, using ATP
C) Allowing passive diffusion of sodium
D) Creating an acidic intracellular environment
ANSWER: A) Moving 3 Na+ out and 2 K+ in, using ATP
Rationale: The Na+/K+-ATPase actively transports 3 sodium ions out of the cell and 2 potassium ions
into the cell against their concentration gradients, consuming one ATP molecule per cycle. This creates
the electrochemical gradient essential for nerve impulses, secondary active transport, and cell volume
regulation. Pump failure leads to cellular swelling and dysfunction, as seen in ischemic injury.
9. Cellular injury from hypoxia primarily results from:
A) Increased ATP production
B) Decreased ATP production leading to pump failure and ionic imbalances
C) Enhanced protein synthesis
D) Improved calcium regulation
ANSWER: B) Decreased ATP production leading to pump failure and ionic imbalances
Rationale: Hypoxia impairs oxidative phosphorylation in mitochondria, reducing ATP production. This
causes Na+/K+-ATPase pump failure, leading to sodium and water influx (cellular swelling), potassium
loss, calcium accumulation, and eventual cell death if prolonged. The cell switches to anaerobic
glycolysis (inefficient), causing lactic acid accumulation and decreased pH, further damaging cellular
proteins and membranes.
10. Receptor down-regulation occurs when:
A) Prolonged exposure to an agonist decreases receptor numbers
B) Brief exposure increases receptors
C) Receptors permanently disappear
D) Signal strength increases
,ANSWER: A) Prolonged exposure to an agonist decreases receptor numbers
Rationale: Down-regulation is a protective mechanism where chronic stimulation causes cells to reduce
receptor numbers through internalization and degradation, decreasing sensitivity to the signal. This
explains tolerance to medications and some hormonal therapies. Conversely, up-regulation occurs with
prolonged antagonist exposure or decreased ligand availability. Understanding this mechanism is crucial
for medication management in chronic conditions.
HARD QUESTIONS (11-15)
11. A patient with chronic hypoxemia develops increased red blood cell production. This represents
which cellular adaptation, and what is the primary signaling mechanism?
A) Hyperplasia; mediated by erythropoietin stimulation of bone marrow stem cells
B) Hypertrophy; mediated by direct oxygen sensing
C) Metaplasia; mediated by transcription factor activation
D) Dysplasia; mediated by genetic mutations
ANSWER: A) Hyperplasia; mediated by erythropoietin stimulation of bone marrow stem cells
Rationale: Chronic hypoxemia triggers renal production of erythropoietin (EPO), which stimulates bone
marrow erythroid progenitor cells to proliferate and differentiate, increasing RBC numbers
(hyperplasia). This compensatory mechanism improves oxygen-carrying capacity but can become
pathologic (polycythemia) if excessive, increasing blood viscosity and thrombotic risk. Hypoxia-inducible
factor (HIF) regulates EPO gene expression, demonstrating the sophisticated cellular response to
environmental changes.
12. In the context of cellular signaling, cross-talk between pathways is important because:
A) It prevents any cellular response
B) It allows integration of multiple signals for coordinated cellular responses and prevents
excessive activation
C) It only occurs in pathologic states
D) It eliminates the need for receptors
ANSWER: B) It allows integration of multiple signals for coordinated cellular responses and prevents
excessive activation
, Rationale: Cross-talk describes interaction between different signaling pathways, allowing cells to
integrate multiple environmental signals and produce appropriate, coordinated responses. For example,
growth factor and stress pathways may converge on common transcription factors. This prevents
isolated pathway hyperactivation and allows for context-dependent cellular decisions. Dysregulated
cross-talk contributes to diseases like cancer, where normal growth control is lost.
13. A cell exposed to free radicals experiences oxidative stress. Which cellular mechanism provides
the primary defense?
A) Increased ATP production
B) Antioxidant systems including superoxide dismutase, catalase, and glutathione
C) Enhanced glycolysis
D) Increased receptor expression
ANSWER: B) Antioxidant systems including superoxide dismutase, catalase, and glutathione
Rationale: Cells defend against reactive oxygen species (ROS) through enzymatic (superoxide dismutase
converts superoxide to hydrogen peroxide; catalase and glutathione peroxidase convert hydrogen
peroxide to water) and non-enzymatic (vitamins C, E, glutathione) antioxidants. Oxidative stress occurs
when ROS production exceeds antioxidant capacity, damaging lipids, proteins, and DNA. This contributes
to aging, atherosclerosis, neurodegenerative diseases, and cancer. Understanding this is crucial for
therapeutic interventions.
14. The unfolded protein response (UPR) in endoplasmic reticulum stress represents:
A) A purely destructive process
B) An adaptive response that can either restore homeostasis or trigger apoptosis depending on
stress severity and duration
C) A mechanism only active in cancer cells
D) Simple protein degradation
ANSWER: B) An adaptive response that can either restore homeostasis or trigger apoptosis depending
on stress severity and duration
Rationale: ER stress from accumulation of misfolded proteins activates the UPR, which initially attempts
to restore homeostasis by reducing protein translation, increasing chaperone production, and enhancing
ER-associated degradation (ERAD). If stress is prolonged or severe, the UPR switches to pro-apoptotic
PATHOPHYSIOLOGY FOR ADVANCED PRACTICE
,Table of Contents
PART I: Foundational Physiologic Concepts
Unit I: The Cell
1. Cellular Biology, Regulation, and Control Mechanisms
2. Cellular and Tissue Physiology
3. Bioenergetics and Body Metabolism
4. Body Fluid Homeostasis
Unit II: Genetics and Genomics
5. Basic Genetics
6. Patterns of Inheritance, Mitochondrial Inheritance, Epigenetics, and Selected Associated
Disorders
Unit III: Inflammation, Immunity, Infection, and Cancer Biology
7. Innate Immunity and Inflammation
8. Adaptive Immunity
9. Infectious Processes and Body Responses
10. Abnormal Cell Growth and Cancer Biology
PART II: Pathophysiology of Disorders Within Specific Body Systems
Section: Oxygenation and Perfusion
Unit IV: Cardiovascular System
11. Review of Cardiovascular Development, Structure, and Function
12. Vascular Disorders
13. Cardiac Disorders
14. Congenital Heart Disease Across the Lifespan
, 15. Shock and Multiple Organ Dysfunction Syndrome
Unit V: Pulmonary System
16. Review of Pulmonary Structure, Development, and Function
17. Congenital, Obstructive, and Restrictive Pulmonary Disorders
18. Infectious Pulmonary Disorders and Lung Cancer
Unit VI: Renal-Urinary System
19. Review of Renal System Structure, Development, and Function
20. Urinary Tract Disorders
21. Kidney Disorders
Unit VII: Hematologic and Lymphatic System
22. Review of Hematologic System Development, Structure, and Function
23. Hematologic and Lymphatic System Disorders
Section: Sensation, Mobility, and Regulation
Unit VIII: Nervous System
24. Review of Nervous System Development, Structure, and Function
25. Central Nervous System Disorders
26. Peripheral Nervous System Disorders
27. Disorders of the Special Senses
28. Mental Health Disorders
Unit IX: Musculoskeletal System
29. Review of Musculoskeletal Development, Structure, and Function
30. Muscle and Tendon Disorders
31. Bone and Joint Disorders
Unit X: Endocrine System
, 32. Review of Endocrine Structure, Function, and Interactions
33. Disorders of the Hypothalamus, Pituitary Glands, and Adrenal Glands
34. Disorders of the Thyroid Gland and Parathyroid Glands
35. Glycemic Control and Diabetes Mellitus
Section: Protection, Nutrition, and Reproduction
Unit XI: Disorders of Immunity
36. Disorders of Reduced Immune Function
37. Hypersensitivity and Autoimmune Disorders
Unit XII: Integumentary System
38. Review of Integumentary Development, Structure, and Function
39. Integumentary System Disorders
Unit XIII: Digestive System
40. Review of Gastrointestinal Development, Structure, and Function
41. Disorders of the Mouth, Throat, Esophagus, and Stomach
42. Disorders of the Small Intestine, Large Intestine, Pancreas, and Hepatobiliary System
Unit XIV: Reproductive Systems
43. Review of Reproductive System Development, Structure, Function, and Sex Chromosome
Abnormalities
44. Common Disorders of the Female Reproductive System
45. Male Reproductive Disorders
46. Sexually Transmitted Infections
47. Physiology and Pathophysiology of the Breast
,PART I: Foundational Physiologic Concepts
CHAPTER 1: Cellular Biology, Regulation, and Control Mechanisms
EASY QUESTIONS (1-5)
1. Which organelle is primarily responsible for ATP production in the cell?
A) Nucleus
B) Mitochondria
C) Ribosome
D) Golgi apparatus
ANSWER: B) Mitochondria
Rationale: Mitochondria are the "powerhouses" of the cell, responsible for producing ATP through
oxidative phosphorylation and the citric acid cycle. The nucleus contains genetic material, ribosomes
synthesize proteins, and the Golgi apparatus packages and modifies proteins. Understanding cellular
energy production is fundamental to comprehending cellular dysfunction in disease states.
2. The primary function of the endoplasmic reticulum (ER) is:
A) DNA replication
B) Protein synthesis and lipid metabolism
C) Waste elimination
D) Cell division
ANSWER: B) Protein synthesis and lipid metabolism
Rationale: The rough ER synthesizes proteins (due to attached ribosomes), while the smooth ER is
involved in lipid synthesis, detoxification, and calcium storage. DNA replication occurs in the nucleus,
waste elimination involves lysosomes and cellular transport mechanisms, and cell division involves the
nucleus and cytoskeleton. ER dysfunction is implicated in various pathologic conditions including ER
stress responses.
3. Which type of cellular junction allows for direct communication between adjacent cells?
, A) Tight junctions
B) Desmosomes
C) Gap junctions
D) Adherens junctions
ANSWER: C) Gap junctions
Rationale: Gap junctions contain connexon channels that allow small molecules and ions to pass directly
between adjacent cells, enabling electrical and metabolic coupling. Tight junctions seal spaces between
cells, desmosomes provide mechanical strength, and adherens junctions connect actin filaments
between cells. Gap junction dysfunction can lead to cardiac arrhythmias and other pathologic states.
4. The cell membrane is primarily composed of:
A) Carbohydrates only
B) Phospholipid bilayer with embedded proteins
C) Pure cholesterol
D) Nucleic acids
ANSWER: B) Phospholipid bilayer with embedded proteins
Rationale: The cell membrane consists of a phospholipid bilayer with hydrophilic heads facing outward
and hydrophobic tails facing inward, embedded with proteins that serve as receptors, channels, and
transporters. Cholesterol is present but not the primary component, and carbohydrates form glycocalyx
on the surface. Understanding membrane structure is essential for comprehending drug transport and
cellular signaling.
5. Apoptosis is best described as:
A) Accidental cell death due to injury
B) Programmed cell death
C) Cellular division
D) Cellular hypertrophy
ANSWER: B) Programmed cell death
,Rationale: Apoptosis is controlled, programmed cell death that is essential for normal development and
tissue homeostasis. It differs from necrosis (accidental death from injury), which causes inflammation.
Apoptosis involves caspase activation, DNA fragmentation, and phagocytosis without inflammatory
response. Dysregulated apoptosis contributes to cancer (too little) or degenerative diseases (too much).
MEDIUM QUESTIONS (6-10)
6. G-protein coupled receptors (GPCRs) function by:
A) Directly opening ion channels
B) Activating intracellular second messenger cascades
C) Transporting molecules across membranes
D) Binding directly to DNA
ANSWER: B) Activating intracellular second messenger cascades
Rationale: GPCRs are transmembrane receptors that, when activated by ligand binding, activate G-
proteins which then trigger second messenger systems (cAMP, IP3, DAG, calcium). This amplifies signals
and allows for complex regulation. GPCRs are targets for approximately 30-40% of therapeutic drugs.
They don't directly open channels (that's ligand-gated channels) or bind DNA (that's nuclear receptors).
7. Which cellular adaptation involves an increase in cell size without an increase in cell number?
A) Hyperplasia
B) Hypertrophy
C) Metaplasia
D) Dysplasia
ANSWER: B) Hypertrophy
Rationale: Hypertrophy is increased cell size, often in response to increased workload (e.g., cardiac
muscle in hypertension). Hyperplasia is increased cell number, metaplasia is replacement of one cell
type with another, and dysplasia is disordered cell growth. Some tissues can undergo both hypertrophy
and hyperplasia (e.g., uterus during pregnancy), while permanent cells like cardiac myocytes can only
hypertrophy.
,8. The Na+/K+-ATPase pump maintains cellular homeostasis by:
A) Moving 3 Na+ out and 2 K+ in, using ATP
B) Moving 2 Na+ out and 3 K+ in, using ATP
C) Allowing passive diffusion of sodium
D) Creating an acidic intracellular environment
ANSWER: A) Moving 3 Na+ out and 2 K+ in, using ATP
Rationale: The Na+/K+-ATPase actively transports 3 sodium ions out of the cell and 2 potassium ions
into the cell against their concentration gradients, consuming one ATP molecule per cycle. This creates
the electrochemical gradient essential for nerve impulses, secondary active transport, and cell volume
regulation. Pump failure leads to cellular swelling and dysfunction, as seen in ischemic injury.
9. Cellular injury from hypoxia primarily results from:
A) Increased ATP production
B) Decreased ATP production leading to pump failure and ionic imbalances
C) Enhanced protein synthesis
D) Improved calcium regulation
ANSWER: B) Decreased ATP production leading to pump failure and ionic imbalances
Rationale: Hypoxia impairs oxidative phosphorylation in mitochondria, reducing ATP production. This
causes Na+/K+-ATPase pump failure, leading to sodium and water influx (cellular swelling), potassium
loss, calcium accumulation, and eventual cell death if prolonged. The cell switches to anaerobic
glycolysis (inefficient), causing lactic acid accumulation and decreased pH, further damaging cellular
proteins and membranes.
10. Receptor down-regulation occurs when:
A) Prolonged exposure to an agonist decreases receptor numbers
B) Brief exposure increases receptors
C) Receptors permanently disappear
D) Signal strength increases
,ANSWER: A) Prolonged exposure to an agonist decreases receptor numbers
Rationale: Down-regulation is a protective mechanism where chronic stimulation causes cells to reduce
receptor numbers through internalization and degradation, decreasing sensitivity to the signal. This
explains tolerance to medications and some hormonal therapies. Conversely, up-regulation occurs with
prolonged antagonist exposure or decreased ligand availability. Understanding this mechanism is crucial
for medication management in chronic conditions.
HARD QUESTIONS (11-15)
11. A patient with chronic hypoxemia develops increased red blood cell production. This represents
which cellular adaptation, and what is the primary signaling mechanism?
A) Hyperplasia; mediated by erythropoietin stimulation of bone marrow stem cells
B) Hypertrophy; mediated by direct oxygen sensing
C) Metaplasia; mediated by transcription factor activation
D) Dysplasia; mediated by genetic mutations
ANSWER: A) Hyperplasia; mediated by erythropoietin stimulation of bone marrow stem cells
Rationale: Chronic hypoxemia triggers renal production of erythropoietin (EPO), which stimulates bone
marrow erythroid progenitor cells to proliferate and differentiate, increasing RBC numbers
(hyperplasia). This compensatory mechanism improves oxygen-carrying capacity but can become
pathologic (polycythemia) if excessive, increasing blood viscosity and thrombotic risk. Hypoxia-inducible
factor (HIF) regulates EPO gene expression, demonstrating the sophisticated cellular response to
environmental changes.
12. In the context of cellular signaling, cross-talk between pathways is important because:
A) It prevents any cellular response
B) It allows integration of multiple signals for coordinated cellular responses and prevents
excessive activation
C) It only occurs in pathologic states
D) It eliminates the need for receptors
ANSWER: B) It allows integration of multiple signals for coordinated cellular responses and prevents
excessive activation
, Rationale: Cross-talk describes interaction between different signaling pathways, allowing cells to
integrate multiple environmental signals and produce appropriate, coordinated responses. For example,
growth factor and stress pathways may converge on common transcription factors. This prevents
isolated pathway hyperactivation and allows for context-dependent cellular decisions. Dysregulated
cross-talk contributes to diseases like cancer, where normal growth control is lost.
13. A cell exposed to free radicals experiences oxidative stress. Which cellular mechanism provides
the primary defense?
A) Increased ATP production
B) Antioxidant systems including superoxide dismutase, catalase, and glutathione
C) Enhanced glycolysis
D) Increased receptor expression
ANSWER: B) Antioxidant systems including superoxide dismutase, catalase, and glutathione
Rationale: Cells defend against reactive oxygen species (ROS) through enzymatic (superoxide dismutase
converts superoxide to hydrogen peroxide; catalase and glutathione peroxidase convert hydrogen
peroxide to water) and non-enzymatic (vitamins C, E, glutathione) antioxidants. Oxidative stress occurs
when ROS production exceeds antioxidant capacity, damaging lipids, proteins, and DNA. This contributes
to aging, atherosclerosis, neurodegenerative diseases, and cancer. Understanding this is crucial for
therapeutic interventions.
14. The unfolded protein response (UPR) in endoplasmic reticulum stress represents:
A) A purely destructive process
B) An adaptive response that can either restore homeostasis or trigger apoptosis depending on
stress severity and duration
C) A mechanism only active in cancer cells
D) Simple protein degradation
ANSWER: B) An adaptive response that can either restore homeostasis or trigger apoptosis depending
on stress severity and duration
Rationale: ER stress from accumulation of misfolded proteins activates the UPR, which initially attempts
to restore homeostasis by reducing protein translation, increasing chaperone production, and enhancing
ER-associated degradation (ERAD). If stress is prolonged or severe, the UPR switches to pro-apoptotic
