16 Questions
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.
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.
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.
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.
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).
What are the two main pathways of apoptosis?
Extrinsic - caspase 8, Intrinsic - caspase 9
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.
What are the three ways in which DNA damage can affect cells?
Lipid → Membrane Damage, Protein → Break+Misfold, DNA → Mutations
What is the result of extensive DNA damage in a cell?
Apoptosis
What are the executioner caspases involved in apoptosis?
Caspases 3, 6, 7
What happens during the recognition/phagocytosis phase of apoptosis?
Cell fragments are recognized and engulfed by macrophages or neighboring cells to avoid inflammatory responses.
What is the main difference between apoptosis and necrosis?
Apoptosis is programmed cell death, while necrosis is accidental cell death.
What is the main trigger for necrosis and its result?
Main trigger is damaged lysosomes, and the result is an inflammatory reaction.
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
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.
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