Cell Injury and Death: Apoptosis vs Necrosis

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Questions and Answers

Explain the difference between apoptosis and necrosis.

Apoptosis is a programmed cell death that can be physiological or pathological, while necrosis is always pathological and occurs when cells can't survive in adverse conditions.

What are the main pathways of apoptosis?

The main pathways of apoptosis include the intrinsic pathway (mitochondrial pathway) and the extrinsic pathway (death receptor pathway).

Describe the causes and mechanisms of cell injury.

Cell injury can be caused by various factors such as lack of oxygen (anoxia or hypoxia), trauma, radiation, poisons, and infections. Mechanisms include ATP depletion, cell membrane permeability changes, protein synthesis disruption, and DNA damage.

What are the 4 main targets of cell injury?

The 4 main targets of cell injury are ATP depletion, cell membrane permeability changes, protein synthesis disruption, and DNA damage. Signup and view all the answers

What activates DNases in apoptosis and what is their role?

Caspases activate DNases in apoptosis. DNases are responsible for breaking up the DNA during the apoptotic process. Signup and view all the answers

Explain the term 'ischemia' in the context of cell injury.

Ischemia refers to inadequate blood supply to a region, which can lead to cell injury and death. Signup and view all the answers

What happens when intracellular Ca+ levels increase in a cell?

An increase in intracellular Ca+ levels can activate phospholipases, proteases, and endonucleases, which can damage the cell membrane, cytoskeleton, and DNA. Signup and view all the answers

What are the common causes of DNA damage in cells?

DNA damage in cells can be caused by factors like radiation, toxins, and reactive oxygen species (ROS). Signup and view all the answers

What are the two main pathways of apoptosis?

Extrinsic - caspase 8, Intrinsic - caspase 9 Signup and view all the answers

How does mitochondrial damage contribute to cell death?

By causing high conductance channel in the membrane which decreases ATP production and leads to cytochrome c leakage into the cytosol, triggering apoptosis. Signup and view all the answers

What are the three ways in which DNA damage can affect cells?

Lipid → Membrane Damage, Protein → Break+Misfold, DNA → Mutations Signup and view all the answers

What is the result of extensive DNA damage in a cell?

Apoptosis Signup and view all the answers

What are the executioner caspases involved in apoptosis?

Caspases 3, 6, 7 Signup and view all the answers

What happens during the recognition/phagocytosis phase of apoptosis?

Cell fragments are recognized and engulfed by macrophages or neighboring cells to avoid inflammatory responses. Signup and view all the answers

What is the main difference between apoptosis and necrosis?

Apoptosis is programmed cell death, while necrosis is accidental cell death. Signup and view all the answers

What is the main trigger for necrosis and its result?

Main trigger is damaged lysosomes, and the result is an inflammatory reaction. Signup and view all the answers

Study Notes

Cell Injury and Death

Cell injury can lead to two types of cell death: apoptosis and necrosis
Apoptosis is a tactical suicide that can be physiological or pathological, whereas necrosis is always pathological

Apoptosis

Apoptosis is a programmed cell death that can be initiated by various stimuli, including DNA damage, protein misfolding, and growth factor withdrawal
There are two main pathways of apoptosis: extrinsic (caspase 8) and intrinsic (caspase 9)
Apoptosis involves the activation of caspases, which break down DNA and lead to cell death
Physiological apoptosis occurs during development, immune response, and tissue homeostasis
Pathological apoptosis can occur in diseases such as cancer, neurodegenerative disorders, and autoimmune diseases

Necrosis

Necrosis is an accidental cell death that occurs due to external factors such as injury, toxins, and infection
Necrosis leads to an inflammatory response and can cause tissue damage
Necrosis can occur due to various factors, including ischemia, trauma, radiation, and poisons
There are different types of necrotic death, including gangrene, black necrosis, and cottage cheese-like appearance

Causes of Cell Injury

Ischemia: inadequate blood supply to a region
Cardio-respiratory failure
Anemia
Parasites/bacteria
Immunodeficiency/autoimmune disorders
Anaphylaxis
Down syndrome
Obesity/anorexia/bulimia
Increased ROS/mutation/telomere shortening

Mechanisms of Cell Injury

Oxidative stress and ROS generation
Mitochondrial damage and ATP depletion
Cell membrane permeability and calcium influx
DNA damage and protein misfolding
ER stress and cellular swelling
Lipid deposition and protein synthesis inhibition
Nuclear chromatin clumping and DNA fragmentation

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Description

Learn about the causes and mechanisms of cell injury, differences between apoptosis and necrosis, physiological and pathological apoptosis, main pathways of apoptosis, and different types of necrotic death. Topics also include anoxia, hypoxia, trauma, and radiation.