Cell Injury Overview

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Questions and Answers

What process allows cells to maintain their internal environment despite external stress?

Adaptation

Cell death

Cell injury

Homeostasis (correct)

Which of the following best defines reversible injury in cells?

Genetic mutation without effects

Irreversible changes in cell structure

Permanent cell death

Restoration of normal function when stress is removed (correct)

What is a common cause of cell injury related to oxygen supply?

Hypoxia and ischemia (correct)

Toxins in medication

Age-related changes

Nutritional imbalance

How do toxins typically contribute to cell injury?

They disrupt cell homeostasis. Signup and view all the answers

Which of the following is NOT considered a physical agent that can cause cell injury?

Cigarette smoke Signup and view all the answers

Which factor primarily impacts the ability of cells to respond to stress as they age?

Decreased adaptive capacity Signup and view all the answers

What mechanism is employed by cells to deal with impaired function during reversible injury?

Cell swelling Signup and view all the answers

Which of the following conditions is related to genetic abnormalities causing cell injury?

Functional protein deficiencies Signup and view all the answers

What is one of the primary morphological changes observed in reversible injury?

Fatty changes Signup and view all the answers

Which option describes a characteristic of cellular edema?

Paleness and increased turgor Signup and view all the answers

What does hypoxic hypoxia result from?

Inadequate oxygen in the blood Signup and view all the answers

Which of the following represents a mechanism of cell injury due to hypoxia?

Decreased activity of Na+ - K+ Pump Signup and view all the answers

What is a consequence of anaerobic glycolysis during hypoxia?

Accumulation of lactic acid and inorganic phosphates Signup and view all the answers

How does ischemic hypoxia occur?

From inadequate blood supply to tissues Signup and view all the answers

What might occur in cells during reversible injury that indicates damage but does not lead to cell death?

Formation of myelin figures Signup and view all the answers

What happens to cell function following injury despite morphological changes being undetected?

Cell functions cease prior to visual detection of injury Signup and view all the answers

Study Notes

Cell Injury

Cell injury is a process in which cells are damaged.
The response to injury depends on the type, duration, and severity of the injury.
The response depends on the type of cell, the cell's adaptive capacity, and the cell's genetic composition.
Cells experience functional and biochemical abnormalities.
Cell function is lost before biochemical and morphological changes are visible.

Introduction

Body cells adapt to their environment.
Homeostasis is the maintenance of a stable internal environment within acceptable limits.
Cells adapt to physical stress (increased workload), or harmful conditions (nutrient deficiency).
Cells maintain viability and function after adapting.
Cell injury occurs when the capacity to adapt or stress exceeds a certain level.
Cell injury can be reversible; cells can return to their original state.
Irreversible injury occurs with prolonged exposure to stressors; the cell dies.
Cell death is a normal and significant process in embryogenesis, organ development, and maintenance of homeostasis.

Causes of Cell Injury

Hypoxia and Ischemia:
- Hypoxia is reduced oxygen supply below physiological levels.
- Ischemia is a reduced blood supply.
- They are common causes of cell injury.
Toxins:
- Found in the environment (carbon dioxide, smoke, alcohol, drugs).
- Some medicine at therapeutic dosages can damage cells and tissues.
- All viruses, bacteria, fungi, and protozoa can damage cells.
Physical agents:
- Trauma, high temperatures, radiation, electric current.
- Changes in atmospheric pressure can damage cells.
Immunological Reactions:
- Autoimmune reactions and allergic reactions damage cells.
Genetic Abnormalities:
- Deficiencies in functional proteins can damage cells.
Nutritional Imbalances:
- A major cause of cell injury.
Aging:
- Reduces a cell's ability to respond to stress and can lead to cell death.

Reversible Injury

Reversible injury is a stage where impaired cell function and morphology can be eliminated if the harmful stimuli are removed.
Cells and intracellular organelles generally swell due to water absorption.
Cell homeostasis is disrupted during reversible injury.

Morphological Changes in Reversible Injury

Cellular edema: clearly visible at the organ level. Paleness, increased turgor, and increased organ mass are observed during macroscopic examination. Small vacuoles are visible in the cytoplasm under a microscope.
Fatty changes: occur in the cytoplasm of cells.
Other changes include: increased redness of the cytoplasm, plasma membrane swelling, weakening of intercellular connections, accumulation of chromatin, and amorphous formations (myelin figures - aggregations of phospholipids).

General Principles of Cell Injury

Cellular response to injury depends on the type, duration, and severity of the injury.
The outcome of exposure depends on the cell type, its adaptive capacity, and its genetic makeup.
Cell injury typically arises from functional and biochemical abnormalities within one or more major cellular components.
Cell function often declines before detectable biochemical or morphological signs of injury appear.

Mechanism of Cell Injury (Hypoxia and Ischemia)

Hypoxia is a decrease in oxygen supply to tissues below normal levels.
A critical and common cause of cell injury and death.
Reduced ATP production.
Failure of Na+-K+ pumps.
Glycolysis increases; lactic acid and inorganic phosphates accumulate.
Protein synthesis decreases; lipids accumulate.
All of these changes are reversible if the oxygen supply is restored.

Mechanism of Cell Injury (Toxins)

Toxins cause cell injury through distinct mechanisms.
Some toxins directly bind to crucial molecular components or organelles.
Other toxins transform into reactive metabolites that affect cells.

Types of Hypoxia

Anemic: decreased blood oxygen due to low hemoglobin (e.g., hemolytic anemia).
Histotoxic: impaired oxygen use by tissues (e.g., carbon monoxide poisoning)
Hypoxic (or ischemia): insufficient oxygen supply to the blood (e.g., drowning).
Ischemic: reduced blood supply to cells.
Stagnant: insufficient blood supply (e.g., circulatory failure).

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Description

Explore the process of cell injury, including its causes, responses, and the difference between reversible and irreversible injuries. Understand the factors that influence cellular damage and the importance of homeostasis in maintaining cell function. This quiz will enhance your knowledge of cellular adaptation and injury mechanisms.