1- Cell Injury Flashcards
List the causes of cell injury
“Oxygen deprivation
- Chemical agents
- Infectious agents
- Immunological reactions
- Genetic defects
- Nutritional imbalances
- Physical agents
- Aging
CIPOGAIN
Which 4 intracellular systems are particularly vulnerable to injury?
“. cell membrane integrity, 2. ATP generation, 3. protein synthesis and 4. the integrity of the genetic apparatus ”
Define hypertrophy and give and example
increase in the size of cells and, consequently, an increase in the size of the organ
• Can be caused by increased functional demand or specific hormonal stimulation
• EXAMPLE: cardiomyocytes adaptation to increased stress is hypertrophy
Define hyperplasia and give an example
increase in the NUMBER of cells in an organ
• Can be physiological or pathological
• Physiological Hyperplasia: hormonal or
compensatory
Hormonal - oestrogenic wave of proliferation of the endometrium Compensatory - if some tissue is lost
E.g. cancer
Define atrophy and give an example
shrinking in the size of the cell or organ by the loss of cell substance
Define metaplasia and give an example
Metaplasia - a reversible change in which one adult cell type is replaced by another
• EXAMPLE: Barrett’s Oesophagus - instead of squamous lined epithelium you get columnar epithelium
Define dysplasia and give an example
precancerous cells which show the genetic and cytological features of malignancy but not invading the underlying tissue
• Dysplasia means that it hasn’t invaded the basal lamina
• Cervical cancer screening - aims to identify cells in the dysplastic stage
Compare apoptosis and necrosis
Necrosis - confluent cell death associated with inflammation
• Not just single cells, whole areas of cells die
Apoptosis
Death of SINGLE CELLS
• NOT ASSOCIATED WITH INFLAMMATION
• It is active cell death - energy is used to
die
• Necrosis is associated with being
pathological
• Apoptosis can be physiological or pathological
• Apoptosis is a neater process
• The nucleus shrinks and little bits of the
cell break off (lined by cytoplasm)
• Nothing from inside the cell is exposed to
the outside - so there is NO
INFLAMMATION
• It is phagocytosed by macrophages
NOTE: apoptosis is usually offered as a response to quite mild injury. Necrosis is a response to severe injury.
• Sometimes at the edge of an area of necrosis where injury is less severe you can see apoptosis taking place
“Define the terms necrosis, ulcer, degenerative, sublethal injury. ”
.
Necrosis - confluent cell death associated with inflammation
Ulcer - a local defect, or excavation of the surface, of an organ or tissue, produced by sloughing of necrotic inflammatory tissue
degenerative changes - associated with cell and tissue damage
Sublethal - produce injury not amounting to cell death, may be reversible or
progress to cell death
What causes apoptosis
Embryogenesis - intestines have a lumen because of apoptosis during development
• Deletion of auto-reactive T cells in the thymus
• Hormone dependent physiological involution - e.g. shedding of endometrium
• Cell deletion in proliferating populations
• A variety of mild injurious stimuli that cause irreparable DNA damage that triggers cell suicide pathways
Summarise the difference between apoptosis and necrosis
The differences between apoptosis and necrosis:
- Apoptosis may be physiological
- Apoptosis is an active energy dependent process
- Apoptosis is NOT associated with inflammation
Describe acute pancreatitis
Acute pancreatitis - you get release of lipases which digests the fat and hydrolyses triglycerides to free fatty acids and glycerol
The free fatty acids combine with calcium in the extracellular fluid and deposits
Each of the deposits (white parts) are areas of fat necrosis
The blue fragmented material is calcium
NOTE: Fat necrosis could be due to sufficiently severe fat trauma but it is classically associated with acute pancreatitis
What are the 4 types of necrosis
Coagulative Necrosis
• Liquefactive Necrosis
• Caseous Necrosis
• Fat Necrosis
