Cell Injury and Death

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Questions and Answers

What is the main characteristic of hypertrophy?

Increase in the number of cells

Increase in the size of existing cells (correct)

Replacement of one cell type with another

Shrinkage in cell size

Which of the following describes apotosis?

A form of cell injury leading to cell death

A regulated process leading to cell death (correct)

The formation of new cells from stem cells

An adaptive response to injury

What typically triggers pathological hyperplasia?

Invasive infections

Nutritional imbalances (correct)

Physical exercise

Hormonal stimuli

What distinguishes autophagy from other cell injury mechanisms?

It recycles damaged organelles and proteins Signup and view all the answers

Which mechanism is responsible for cellular swelling in response to injury?

Failure of ion pumps Signup and view all the answers

Which statement about reversible cell injury is true?

It can progress to irreversible injury if stress persists. Signup and view all the answers

What is the goal of cellular adaptations to injury?

To enhance cellular function under stress Signup and view all the answers

Which condition does NOT typically lead to atrophy?

Increased physical activity Signup and view all the answers

Which type of cell death involves the activation of enzymes that degrade the cell's own nuclear DNA and cytoplasmic proteins?

Apoptosis Signup and view all the answers

What is a key feature that differentiates necrosis from apoptosis?

Inflammation is often associated with necrosis. Signup and view all the answers

Which of the following necrosis types is characterized by the transformation of tissue into a liquid viscous mass?

Liquefactive necrosis Signup and view all the answers

In which condition can a cell potentially reverse from dysplasia back to normal?

Removal of the injurious stimulus Signup and view all the answers

What happens to cellular contents during apoptosis?

Contents are phagocytosed without leakage. Signup and view all the answers

What is the potential effect on neighboring cells caused by the remnants of necrotic cells?

They can induce inflammation and damage to surrounding cells. Signup and view all the answers

Which physiological adaptation is characterized by the replacement of one cell type with another to withstand environmental stress?

Metaplasia Signup and view all the answers

What is the role of vATPase at the lysosomal interface during autophagy?

It regulates pH levels necessary for enzyme activity. Signup and view all the answers

What type of cellular adaptation results in an increase in the size of cells?

Hypertrophy Signup and view all the answers

What distinguishes physiological adaptation from pathological adaptation?

Physiological adaptation occurs under normal conditions, while pathological adaptation occurs in response to stress. Signup and view all the answers

Which of the following best describes the mechanism of apoptosis?

A systematic process of cell self-destruction without causing inflammation. Signup and view all the answers

Cell autophagy primarily serves what purpose in cellular health?

To degrade and recycle cellular components. Signup and view all the answers

Which of the following processes is characterized by cellular swelling due to injury?

Reversible cell injury Signup and view all the answers

What is the likely fate of a cell that fails to adapt to increased workload?

Cell death Signup and view all the answers

Which of the following statements about necrosis is true?

Necrosis leads to inflammation and affects surrounding tissues. Signup and view all the answers

Which stimulus is most likely to cause physiological hypertrophy in a cell?

Increased hormonal stimulation Signup and view all the answers

Study Notes

Cell Injury

Cell injury can be caused by functional and biochemical abnormalities of essential cellular components.
Multiple biochemical alterations can be triggered by any one injurious insult.

Cell Death

Cell death can be characterized by loss of membrane integrity, leakage of cellular contents, and eliciting an inflammatory response.
Different patterns of necrosis can indicate the underlying cause.
Coagulative necrosis is characterized by the coagulation of cellular proteins, while liquefactive necrosis is associated with the enzymatic digestion of cells.
Gangrenous necrosis is a type of coagulative necrosis that occurs in extremities, while caseous necrosis is characterized by a cheese-like appearance and is often associated with tuberculosis.

Apoptosis

Apoptosis is a programmed cell death pathway, also known as cell suicide.
In apoptosis, cells activate enzymes that degrade their own DNA and proteins.
The cell membrane remains intact, but it is altered in a way that triggers phagocytosis.
This eliminates the cell before cellular contents leak, preventing inflammation.

Necrosis vs. Apoptosis

Necrosis is a form of cell death that is caused by injury or stress.
Apoptosis is a form of programmed cell death.
Feature | Necrosis | Apoptosis
-- | --- | ---
Cell Size | Enlarged | Shrunken
Nucleus | Pyknotic, fragmented, or dissolved | Fragmentation into nucleosome-sized fragments
Plasma membrane | Disrupted | Intact, altered structure leading to phagocytosis
Cellular Contents | Enzymatic digestion, leakage | Release of apoptotic bodies
Adjacent Inflammation | Present | Absent
Physiologic or Pathologic Role | Pathologic | Physiologic/Pathologic

Autophagy

Autophagy is a cellular process that involves the degradation of cellular components.
It involves formation of a double membrane structure called autophagosomes.
This structure engulfs cellular components for degradation by lysosomes.
vATPase (vacuolar ATPase) is necessary for lysosomal function in autophagy. Without vATPase, autophagosomes may not be degraded properly and could accumulate within the cell.

Metaplasia and Dysplasia

Metaplasia is a reversible change in which one adult cell type is replaced by another adult cell type.
It's a response to stress or injury that allows the cells to become more resistant to the damaging stimulus.
Metaplasia can occur when stem cells are reprogrammed or when differentiated cells change phenotype.
Dysplasia is a change in cell growth and differentiation that can precede cancer.
It's often considered a precancerous lesion.
Metaplasia can progress to dysplasia if the stress or injury persists.
Dysplasia is not always reversible and can lead to cancer.
The point of irreversibility is determined by the severity and duration of the underlying stress or injury.

Hyperplasia

Hyperplasia is an increase in the number of cells in an organ or tissue.
It's often caused by hormonal stimulation or increased demand.
Hyperplasia can be physiological or pathological.
Physiological hyperplasia is a normal response to stimuli and is essential for growth and development.
Pathological hyperplasia is an abnormal response to stimuli and can lead to disease.
Goal of Adaption: To increase the number of functional cells to meet the increased demand, or to replace damaged cells.

Hypertrophy

Hypertrophy is an increase in the size of cells.
It occurs when cells cannot divide.
It's often caused by increased workload or hormonal stimulation.
Hypertrophy is generally accompanied by an increase in the amount of protein and organelles within the cells.
Goal of Adaption: To increase the functional capacity of the organ or tissue.

Atrophy

Atrophy is a decrease in the size of cells.
It occurs when cells are not stimulated or receive insufficient nutrition.
It can occur in any cell type, but it is most common in skeletal muscle, heart, and brain.
Goal of Adaption: To reduce the energy expenditure of a cell to protect itself from further damage.

Overview of Cell Injury

Cell injury can be reversible or irreversible.
Reversible cell injury refers to changes in cell function and morphology that are reversible if the stress or injury is removed.
Irreversible cell injury refers to changes in cell function and morphology that are not reversible, leading to cell death.

Cellular Response to Injury

The cell's response to injury depends on several factors, including the type of injury, its duration, and severity.
The consequences of an injurious stimulus depend on the cell's type, status, adaptability, and genetic makeup.

Mechanisms of Cell Injury

Hypoxia: Oxygen deprivation, a major cause of cell injury, can occur due to ischemia or reduced blood flow.
Chemical agents: Chemicals can injure cells by interfering with normal cellular function, such as metabolism or energy production.
Infectious agents: Viruses, bacteria, fungi, and parasites can cause cell injury through a variety of mechanisms, including direct infection, release of toxins, and triggering of inflammatory responses.
Immunologic reactions: The immune system can also cause cell injury through mechanisms like autoimmune reactions and hypersensitivity reactions.
Genetic factors: Mutations in genes can lead to defective proteins or enzymes that can cause cell injury.
Nutritional imbalances: Deficiencies or excesses of nutrients can disrupt normal cellular function, leading to cell injury.
Physical agents: Physical agents like trauma, extreme temperatures, radiation, and electricity can cause cell injury.
Aging: The process of aging can lead to cellular senescence and increased vulnerability to injury.

Morphology of Cell Injury

The morphological changes associated with cell injury can be categorized as cellular swelling and fatty change.

Importance of Practice & Teaching

Discussing information helps retain 50% of the knowledge.
Practicing the information helps retain 75% of the knowledge.
Teaching others the information helps retain 90% of the knowledge.

Learning Objectives

Understand the different fates of a cell following an injury or stress.
Comprehend the mechanisms of cell adaptations, including hypertrophy, hyperplasia, atrophy, and metaplasia.
Distinguish between reversible and irreversible cell injury.
Explain the mechanistic changes that can lead to cell injury or death.
Differentiate between apoptosis and necrosis, outlining their mechanisms.
Describe the mechanism of cell autophagy.

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Description

Explore the mechanisms of cell injury, death, and apoptosis in this quiz. Understand different types of necrosis and the biochemical changes that lead to cellular damage. Test your knowledge of the key concepts associated with these critical biological processes.