3- Mechanisms of Disease II: Cell Damage and cell death Flashcards
What are the 6 causes of cell damage?
→ Physical → Genetic → Inflammation → Infection → Traumatic damage → chemical
What are the functions of necrosis?
Removes damaged cells from an organism
Failure to do so may lead to chronic inflammation
Necrosis causes acute inflammation to clear cell debris via phagocytosis
What are the causes of necrosis?
Usually lack of blood supply, e.g. injury, infection, cancer, infarction, inflammation
When does necrosis occur?
→ occurs after stresses such as ischemia, trauma and chemical injury
What is the most common cause of cell death?
→ Necrosis
What is apoptosis?
→ Programmed cell death
What are the three basic mechanisms of cell death?
→ Necrosis
→ Apoptosis
→ Autophagic cell death
What is the relationship between pH + oxygen levels and distance from the vessel?
→ the further away from the blood vessel the O2 and pH drop
What are 2 characteristics of necrosis?
→ Result of an injurious agent or event. Whole groups of cells are affected
→ reversible events proceed irreversibly
What occurs as a result of O2 deprivation in cells?
→ unable to produce ATP due to O2 deprivation
→ cells swell due to influx of water (ATP needed for ion pumps)
What causes destruction of organelles?
→ Ruptured lysosomes
What does cellular debris released from necrosis cause?
→ Inflammatory cell response
Describe necrosis step-by-step.
- Result of an injurious agent or event. (Whole groups of cells are affected.)
- Initial events are reversible, later ones are not.
- Lack of oxygen prevents ATP production.
- Cells swell due to influx of water (ATP is required for ion pumps to work).
- Lysosomes rupture; enzymes degrade other organelles and nuclear material hapzardly
- Cellular debris released, triggering inflammation
What are the 3 types of changes in a necrotic cell?
→ Nuclear
→ Cytoplasmic
→ Biochemical
What are the 3 nuclear changes in necrosis?
→ Chromatin condensation/shrinkage
→ fragmentation of the nucleus
→ dissolution of chromatin by DNAse
What are the 2 cytoplasmic changes in necrosis?
→ Opacification : denaturation of proteins with aggregation
→ complete digestion of cells by enzymes cause the cell to liquefy (liquefactive necrosis)
What are the 2 biochemical changes in necrosis?
→ Release of enzymes such as creatine kinase or lactase dehydrogenase which can be measured in the lab → myoglobin released
What happens in astrocytoma?
As tumour grows the surrounding vascularisation, the blood vessels become further from the middle
Such that as cancer progresses- it is important that they are able to induce their own vascularisation to supply themselves with blood as they grow