Cell Fate and Injury Flashcards
What is Lethal and sublethal cell injury?
Lethal: Produces cell death
Sublethal: produces injury which may be reversible
( cell death can also be due to inability of cells to adapt )
What are the causes of cell injury? 8
Oxygen deprivation
Chemical agents
Infectious agents
Immunological reactions
Genetic defects
Nutritional imbalances
Physical agents
Ageing
Which intracellular mechanisms are vulnerable and injury could be lethal?
Cell membrane integrity
ATP generation
Protein synthesis
Integrity of genetic apparatus
How can a lost cell function have a big effect?
Components of a cell are integrally related which can lead to secondary effects.
Cellular function loss followed by cell death followed by morphological changes.
( No ATP –> No membrane … )
What is Atrophy? Give examples ( 2 )
Shrinkage of cell/organ size due to loss of cell substance
- Dementia
- Atrophy secondary to denervation
What is Hypertrophy and why may it occur?
Increase in cell/organ size which can be physiological or pathological.
Due to either Increased functional demand or specific hormonal stimulation
What is a physiological Hypertrophy example?
Uterus:
During pregnancy
What is an example of Pathological hypertrophy?
Myocyte response to increased load : hypertrophy
Common in athletes
What is Hyperplasia?
Increase in the number of cells in an organ which can be pathological or physiological
What is an example of physiological hyperplasia?
Hormonal or compensatory
Uterus
Proliferative Endometrium glands
What is an example of pathological hyperplasia?
Carcinoma
- in a histology mitotic phases could be seen
What is Metaplasia?
Reversible change in which one adult cell type is replaced by another
What is an example of Physiological metaplasia?
Cervix:
Due to acidic pH of vagina, columnar epithelium –> Squamous
What is an example of Pathological metaplasia
Barrett’s Oesophagus:
Due to reflux from stomach squamous epithelium –>
columnar
What is Dysplasia?
Precancerous cells which show genetic and cytological features or malignancy
Do not invade underlying tissue
- Histology: may show an increase in mitotic phase but will still be on the basement membrane ( oesophagus example )
How does Dysplasia differ from metaplasia in Barrett’s oesophagus?
In dysplasia the image of the cells looks darker due to having larger nuclei
What are degenerative changes that can be seen by a light microscope?
Fatty change
Cellular swelling
What is Alcoholic fatty change?
Hepatocytes will be surrounded by an increased number of fat cells - this is reversible
Describe Ballooning degeneration as a characteristic of Alcoholic liver disease?
Damaged cytoskeleton leads to increased protein which causes cell to swell.
- They may look like fat cell but you can see strands of cytoplasm
What is Necrosis?
Cell death linked to inflammation
Affects group of cells
ATP independent
What are changes associated with irreversible injury that can be seen by a light microscope?
Give a pathological example of each.
Coagulative necrosis ( structure becomes fixed ) e.g. Myocardial infarct
Liquefactive necrosis
e.g. Old cerebral infarct - not enough connective tissue to keep in place
Caseous Necrosis ( structureless ) e.g. pulmonary TB
Fat necrosis ( due to inappropriately activated lipase acids ) e.g acute pancreatitis
What is Apoptosis
Physiological process which cases death of individual cells
Blebs form –> apoptotic body –> removed by phagocyte
- do not leak contents out of blebs so there is not inflammation
What are the causes of Apoptosis? ( 5 )
- Embryogenesis
- Deletion of auto-reactive T cells in thymus
- Hormone dependent involution ( uterus after childbirth )
- Cell deletion in proliferating populations
- Mild injurious stimuli causing irreparable DNA damage
What is Necroptosis?
Programmed cell death but associated with inflammation
e.g. viral infections cause
