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Questions and Answers

What is hypertrophy primarily characterized by?

The formation of new cells

An increase in the number of cells

Reduction in overall organ mass

An increase in cell size (correct)

Which of the following best describes hyperplasia?

The death of cells in a tissue

An increase in the number of cells typically due to hormonal influence (correct)

A decrease in metabolic activity of cells

An increase in cell size without a change in numbers

Which type of hypertrophy is triggered by exercise such as weight-lifting?

Compensatory hypertrophy

Physiological hypertrophy (correct)

Stress-induced hypertrophy

Pathological hypertrophy

Which condition is an example of pathological hypertrophy?

Cardiac hypertrophy due to hypertension Signup and view all the answers

What primarily triggers hyperplasia in tissues?

Hormones and growth factors Signup and view all the answers

What percentage reduction in ATP levels is considered critical for cellular damage?

5% - 10% Signup and view all the answers

Which of the following processes is NOT directly dependent on ATP?

Lactic acid fermentation Signup and view all the answers

What can lead to impaired ATP production?

Hypoxia Signup and view all the answers

Which ion's gradient fails due to ATP depletion affecting ATPase pumps?

Na+ Signup and view all the answers

What is a consequence of mitochondrial damage during sustained injury?

Inhibition of protein synthesis Signup and view all the answers

Which is NOT considered an injurious agent that can damage mitochondria?

Increased ATP levels Signup and view all the answers

What is the outcome of a membrane permeability transition in mitochondria?

Impaired oxidative phosphorylation Signup and view all the answers

What is a result of ATP depletion affecting cellular functions?

Diminished ionic gradients Signup and view all the answers

What are the three broad cellular responses to cellular stress?

Adaption, Reversible cell injury, Irreversible cell death Signup and view all the answers

Which of the following is a general category of injurious agents that can cause cell injury?

Toxic substances Signup and view all the answers

What is the key difference between apoptosis and necrosis?

Apoptosis is a controlled process, while necrosis is uncontrolled cell death. Signup and view all the answers

Which morphological feature is associated with reversible cell injury?

Cell swelling Signup and view all the answers

How can necrosis be clinically exploited for diagnosis?

By identifying specific necrotic tissue patterns in biopsies Signup and view all the answers

In what physiological circumstance does apoptosis typically occur?

In response to hormonal changes Signup and view all the answers

What are common cellular adaptations to cellular stress?

Atrophy, hyperplasia, and hypertrophy Signup and view all the answers

What is an example of irreversible cell injury?

Cell death due to cardiac arrest Signup and view all the answers

What is primarily indicated by atrophy in tissues or organs?

Reduced size due to decreased cell size and number Signup and view all the answers

Which of the following conditions is NOT associated with pathological atrophy?

Embryological development Signup and view all the answers

What change does metaplasia involve at the cellular level?

Replacement of one differentiated cell type by another Signup and view all the answers

In which scenario does Barrett's esophagus occur?

Because of acid reflux leading to cell type change Signup and view all the answers

Which of the following is a morphological pattern of necrosis?

Caseous necrosis Signup and view all the answers

What is NOT a broad category of injurious agents causing cell injury?

Enhanced cellular regeneration Signup and view all the answers

Which of the following represents a clinical example of reversible cell injury?

Swelling of the liver due to excessive alcohol intake Signup and view all the answers

What is a direct consequence of oxygen deprivation in cells?

Damage from bacterial/viral infection Signup and view all the answers

Which mechanism is NOT involved in indirect damage resulting from cell injury?

Increased mitochondrial metabolism Signup and view all the answers

What leads to intracellular release of digestive enzymes during lysosomal membrane damage?

Auto-digestion Signup and view all the answers

Which of the following best describes reversible cell injury?

Structural alterations that reverse upon removing the damaging stimulus Signup and view all the answers

Which of the following factors can lead to DNA damage and protein mis-folding?

Oxidative stress Signup and view all the answers

What characterizes the interrelationship of mechanisms involved in cell injury?

They are generally inter-related and complex Signup and view all the answers

In what scenario can the mechanisms of cell injury be offset?

When the insult is mild and transient Signup and view all the answers

Which of the following is an example of the morphological features observed in reversible cell injury?

Cellular swelling Signup and view all the answers

Which of the following is a characteristic of necrosis?

Leakage of cell contents Signup and view all the answers

What is the primary feature distinguishing apoptosis from necrosis?

Programmed cell death Signup and view all the answers

In which type of necrosis is tissue structure preserved?

Coagulative necrosis Signup and view all the answers

Which cellular change is associated with fatty change?

Mitochondrial swelling Signup and view all the answers

What happens to the cell size during necrosis?

It increases Signup and view all the answers

Which of the following is NOT a feature of apoptosis?

Release of cell contents Signup and view all the answers

How does necrosis commonly affect nearby tissues?

Causes inflammation Signup and view all the answers

What is a characteristic of coagulative necrosis?

Preservation of tissue morphology Signup and view all the answers

Which morphological feature is indicative of irreversible cell injury?

Chromatin condensation Signup and view all the answers

What distinguishes gangrenous necrosis from other forms of necrosis?

Presence of necrotic tissues in infection Signup and view all the answers

Study Notes

Cell Injury and Cell Death

Three broad cellular responses can occur as a result of cellular stress.
Categories of injurious agents causing cell injury include oxygen deprivation, physical/environmental factors, chemical agents/toxins/drugs, infectious agents, immunologic reactions, genetic derangements, nutritional imbalances, and aging.
Cellular response to injury depends on the severity, duration and type of insult. Consequences depend on the type, state and adaptability of the cell.
Injurious agents trigger multiple interconnected mechanisms. Cell injury can result if any of the following cellular processes are disrupted: ATP production, mitochondrial integrity, plasma membrane integrity, protein synthesis, and genetic (DNA) integrity.
There are six broad mechanisms responsible for cell injury: ATP depletion, mitochondrial damage, increased intracellular calcium, free radical damage, membrane damage, and DNA damage/protein misfolding. All mechanisms are highly complex and are typically inter-related.
Cell injury can result in reversible or irreversible injury.
Reversible cell injury can be reversed if the initial insult is mild or temporary.

Reversible Cell Injury

Features include morphological changes that are reversible if the damaging stimulus is removed.
Microscopic features include cellular swelling and fatty change.
Ultrastructure features include plasma membrane blebbing, mitochondrial swelling, endoplasmic reticulum (ER) dilation, and chromatin clumping.
Early examples include acute kidney injury (AKI) and hepatic steatosis.

Irreversible Cell Injury/Cell Death

Cell death is characterized by two major forms: apoptosis and necrosis.
Apoptosis is tightly regulated programmed cell death. Cellular contents are contained, and there is no release of contents/surrounding inflammation.
Necrosis involves membrane breakdown, leakage of cell contents into tissues, and inflammation.
Morphological patterns of necrosis include coagulative, liquefactive, caseous, gangrene, fat, and fibrinoid necrosis.

Apoptosis

Apoptosis is a tightly regulated, programmed cellular suicide.
Physiological examples include embryogenesis, hormone-dependent tissue involution, control of cell turnover, elimination of self-reactive lymphocytes, and death of host cells after an immune response.
Pathological examples include DNA damage, accumulation of misfolded proteins, infections, and pathological atrophy.
Two main pathways for apoptosis include the mitochondrial pathway and the death receptor pathway.
Caspase activation is common to both pathways.
Apoptosis is characterized by cell shrinkage, chromatin condensation, cytoplasmic blebs, apoptotic bodies, and a lack of surrounding damage.

Necrosis vs Apoptosis

Necrosis involves increased cell size, a disrupted nucleus (pyknosis, karyolysis, karyorrhexis), a disrupted plasma membrane, and nearly always triggers nearby inflammation. It is always a pathological process.
Apoptosis involves reduced cell size, fragmentation or condensation of the nucleus, an intact plasma membrane, and does not invariably trigger nearby inflammation. It can be physiological or pathological.

Cellular Adaptation, Hypertrophy, Hyperplasia, Atrophy

Cellular adaptations are reversible adjustments in cell size, number, phenotype, and metabolic activity to the changes in their environment.
Hypertrophy is an increase in the size of cells (and thus organs), usually from increased workload(e.g. body-building). Cardiomyocyte hypertrophy is a common pathological adaptation to circulatory stress.
Hyperplasia is an increase in the number of cells in an organ or tissue resulting usually from growth factors or hormones (e.g. breast tissue in pregnancy).
Atrophy is a decrease in the size of an organ or tissue, that occurs from decreased workload, denervation, decreased blood supply, or inadequate nutrition.

Metaplasia

A switch from one differentiated cell type to another, and is often an adaptive response to adverse environmental factors like inflammation.
Examples include the conversion of squamous cells in the esophagus to gastric-like columnar epithelium in response to acid reflux.

Cell Death and Clinical Diagnosis

Myocardial infarction, pancreatitis, and apoptosis are all examples of instances where the necrotic release of certain enzymes into the bloodstream allows for clinical diagnosis. Myocardial infarction is often characterized by a release of cardiac enzymes like troponin into the bloodstream. Pancreatitis leads to elevated amylase and lipase levels in blood. Apoptosis, while not involving release into blood, can be diagnosed microscopically, which is important in disease like liver disease and GVHD(graft versus host disease, particularly in transplantation).

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