Cell Injury and Adaptation

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Questions and Answers

What is the primary characteristic distinguishing necrosis from apoptosis?

Necrosis is always reversible.

Apoptosis occurs mainly in response to injury.

Necrosis involves programmed cell death.

Apoptosis is a regulated process of cell death. (correct)

Which of the following conditions can cause hypoxic cell injury?

High atmospheric pressure.

Inadequate oxygenation of the blood. (correct)

Exposure to extreme chemical agents.

Excessive nutrient intake.

What role does intracellular calcium play in cellular injury?

Calcium levels are irrelevant to cellular viability.

High intracellular calcium can lead to cellular injury. (correct)

Elevated calcium levels promote cell membrane integrity.

Low calcium levels indicate healthy cell function.

Which of the following is NOT a consequence of the exposure to physical agents that cause cell injury?

DNA replication. Signup and view all the answers

How does aging affect cellular response to injury?

Aging can decrease the effectiveness of cellular adaptations. Signup and view all the answers

Which mechanism is primarily affected by physical agents as a cause of cell injury?

Aerobic respiration. Signup and view all the answers

What principle primarily drives the process of apoptosis?

Programmed cellular self-destruction. Signup and view all the answers

What is a significant contributor to atherosclerosis according to nutritional imbalances?

High consumption of animal fat. Signup and view all the answers

What initial effect does hypoxia have on cellular respiration?

Decreases intracellular ATP Signup and view all the answers

Which enzyme is primarily stimulated by decreased levels of ATP and AMP during hypoxia?

Phosphofructokinase Signup and view all the answers

What is a primary consequence of prolonged hypoxia on the ribosomes?

Detachment from rough endoplasmic reticulum (RER) Signup and view all the answers

What is not considered a mechanism of irreversible injury in cells?

Progressive accumulation of ribosomal RNA Signup and view all the answers

What is the main result of extracellular calcium influx during cell injury?

Activation of proteases and phospholipases Signup and view all the answers

Which of the following best describes the role of oxygen free radicals in cell death?

They are mediators of cell death Signup and view all the answers

What structural feature is lost as hypoxia continues within cells?

Cytoskeletal architecture Signup and view all the answers

Which of the following is an effect of reperfusion after ischemic injury?

Calcium-mediated injury Signup and view all the answers

What is the primary outcome of apoptosis in physiological processes?

Programmed cell death Signup and view all the answers

Which of the following stimuli can initiate apoptosis?

Withdrawal of growth factors Signup and view all the answers

Which microscopic feature is characteristic of apoptosis?

Intensely eosinophilic cytoplasm Signup and view all the answers

What usually follows fat necrosis in cases of acute pancreatitis?

Hydrolysis of triglyceride esters Signup and view all the answers

In which scenario would apoptosis NOT typically occur?

During aggressive bacterial infections Signup and view all the answers

Which process is NOT a characteristic of intracellular accumulations?

Accumulation solely in the cytoplasm Signup and view all the answers

What defines storage diseases in terms of intracellular accumulation?

Inability to metabolize normal or abnormal substances Signup and view all the answers

What is a consequence of the activation of endonucleases during apoptosis?

Fragmentation of chromatin Signup and view all the answers

Which of the following best describes free radicals?

Chemical species with a single unpaired electron Signup and view all the answers

What mechanism leads to the formation of superoxide radicals?

Reduction of O2 during normal physiological conditions Signup and view all the answers

Which of the following is a major consequence of lipid peroxidation?

Damage to plasma membranes Signup and view all the answers

What type of injury occurs when a chemical binds to sulfhydryl groups?

Chemical injury Signup and view all the answers

What is generated from the enzymatic catabolism of CCl4 in the liver?

Toxic free radical CCl3. Signup and view all the answers

Which of the following does NOT describe a pattern of reversible cell injury?

Immediate cell necrosis Signup and view all the answers

Which type of damage do free radicals NOT typically cause?

Deactivation of neurotransmitters Signup and view all the answers

What is a common pathway for generating free radicals within a cell?

Absorption of radiant energy Signup and view all the answers

What condition is characterized by an abnormal accumulation of triglycerides within parenchymal cells?

Fatty Change (Steatosis) Signup and view all the answers

Which organ is most commonly associated with fatty change?

Liver Signup and view all the answers

What can cause the accumulation of cholesterol and cholesterol esters in cells during atherosclerosis?

Phagocytic activities of macrophages Signup and view all the answers

What effect does anoxia have on fatty acid metabolism?

Inhibits fatty acid oxidation Signup and view all the answers

What is the appearance of glycogen accumulation under a light microscope?

Vacuoles in the cytoplasm Signup and view all the answers

Which type of cells may contain melanin, leading to the formation of freckles?

Epidermal basal cells Signup and view all the answers

What abnormal accumulation is primarily associated with pathologic calcification?

Calcium salts Signup and view all the answers

What substance is characterized as a hæmoglobin-derived granular pigment that accumulates with excess iron?

Hæmosiderin Signup and view all the answers

Study Notes

Necrosis vs. Apoptosis

Necrosis involves cell death due to injury, characterized by swelling, membrane damage, and inflammation.
Apoptosis is a programmed cell death, involving cell shrinkage, nuclear fragmentation, and no inflammation.

Hypoxic Cell Injury

Hypoxia (oxygen deficiency) can be caused by:
- Reduced blood flow (ischemia)
- Decreased oxygen-carrying capacity of blood (e.g., anemia)
- Impaired diffusion of oxygen from the air into the blood (e.g., high altitude)
Ischemia is the most common cause of hypoxic cell injury.

Intracellular Calcium

Calcium influx into cells can be detrimental, triggering:
- Activation of enzymes that degrade cell components
- Increased mitochondrial permeability, leading to loss of ATP production
- Activation of apoptosis in some cases

Effects of Physical Agents

Physical agents can cause cell injury through:
- Trauma (e.g., mechanical force)
- Temperature extremes (e.g., heat, cold)
- Radiation (e.g., ionizing, non-ionizing)
- Electrical injury
A consequence of physical agents NOT directly causing cell injury is altered blood flow.

Aging and Cell Injury

Aging reduces the cell's ability to respond to injury due to:
- Decreased ATP production
- Reduced protein synthesis
- Accumulation of cellular damage

Physical Agents and Cell Injury Mechanisms

Physical agents primarily affect membrane permeability.

Apoptosis Principle

Apoptosis is driven by the activation of caspases.

Atherosclerosis and Nutrition

Saturated and trans fats contribute to atherosclerosis by promoting the accumulation of LDL cholesterol within blood vessels.

Hypoxia and Cellular Respiration

Hypoxia initially leads to a decrease in ATP production.

Hypoxia and Enzyme Stimulation

Decreased ATP and AMP levels stimulate the enzyme AMP-activated protein kinase (AMPK).

Prolonged Hypoxia and Ribosomes

Prolonged hypoxia causes the ribosomes to detach from the endoplasmic reticulum, leading to a decrease in protein synthesis.

Irreversible Injury Mechanisms

Loss of membrane integrity is NOT considered a mechanism of irreversible injury in cells.

Extracellular Calcium Influx

Extracellular calcium influx during cell injury primarily leads to the activation of enzymes that degrade cellular components.

Oxygen Free Radicals and Cell Death

Oxygen free radicals contribute to cell death by damaging cellular components such as DNA, proteins, and lipids.

Hypoxia and Structural Loss

As hypoxia continues, the cell loses its structural integrity.

Reperfusion Injury

**Reperfusion after ischemic injury can cause additional damage by: **
- Producing reactive oxygen species
- Increasing inflammation
- Altering calcium homeostasis

Apoptosis in Physiological Processes

Apoptosis primarily eliminates unwanted or damaged cells, maintaining homeostasis and tissue remodeling.

Apoptosis Stimuli

**Apoptosis can be initiated by stimuli such as: **
- Withdrawal of growth factors
- DNA damage
- Activation of death receptors

Apoptosis Microscopic Feature

Apoptotic cells are characterized by nuclear fragmentation and condensation.

Fat Necrosis and Pancreatitis

Fat necrosis is a common occurrence in cases of acute pancreatitis, where enzymes from the pancreas damage fat cells.

Apoptosis Scenarios

Apoptosis WOULD NOT typically occur during necrosis.

Intracellular Accumulations

Lysosomal storage diseases are NOT a characteristic of intracellular accumulations.

Storage Diseases

Storage diseases are defined by the accumulation of specific molecules due to genetic defects in the enzymes responsible for their metabolism.

Endonuclease Activation

Activation of endonucleases during apoptosis causes the breakdown of DNA into fragments.

Free Radicals

Free radicals are molecules with an unpaired electron, making them highly reactive and capable of damaging cellular components.

Superoxide Radical Formation

The electron transport chain in mitochondria is a major source of superoxide radicals.

Lipid Peroxidation

Lipid peroxidation is a major consequence of free radical damage, leading to membrane damage and cell dysfunction.

Sulfhydryl Group Binding

Chemicals that bind to sulfhydryl groups can disrupt enzyme function and cause cell injury.

CCl4 Catabolism

CCl4 catabolism in the liver generates free radicals that damage liver cells.

Reversible Cell Injury Patterns

Reversible cell injury patterns do NOT include the loss of membrane integrity.

Free Radical Damage

Free radicals do NOT typically directly cause DNA methylation, which is a process involving the addition of a methyl group to DNA.

Free Radical Generation Pathway

The cytochrome P450 system is a common pathway for generating free radicals within a cell, metabolizing various drugs and toxins.

Triglyceride Accumulation

Steatosis (fatty change) is characterized by an abnormal accumulation of triglycerides within parenchymal cells.

Fatty Change Organ

The liver is the organ most commonly associated with fatty change.

Cholesterol Accumulation in Atherosclerosis

Defective LDL receptors and increased production of LDL cholesterol can cause the accumulation of cholesterol and cholesterol esters in cells during atherosclerosis.

Anoxia and Fatty Acid Metabolism

Anoxia disrupts fatty acid metabolism, leading to an accumulation of triglycerides.

Glycogen Accumulation Appearance

Glycogen accumulation appears as clear vacuoles under a light microscope.

Melanin Containing Cells

Melanocytes are the cells that contain melanin, leading to the formation of freckles.

Pathologic Calcification

Calcium phosphate is the primary abnormal accumulation associated with pathologic calcification.

Hemosiderin

Hemosiderin is a hæmoglobin-derived granular pigment that accumulates with excess iron.

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Description

Explore the concepts of cell injury, including necrosis and apoptosis, as well as the causes such as hypoxia, physical agents, and chemicals. This quiz will test your understanding of how cells respond to various stressors and the mechanisms behind cell death. Prepare to deepen your knowledge of cellular pathology.