Cell Injury And Fate Flashcards
Why might a cell have to adapt and shift away from being a normal cell/ homeostasis?
Stress, increased demand
What are the two types of cell injury?
Sublethal and lethal
What is lethal cell injury?
one that produces cell death
what is sublethal injury?
Produces injury but not amounting to cell death - may be reversible or even progress to cell death
What are seven causes of cell death?
- Oxygen deprivation
- Chemical agents
- Infectious agents
- Immunological reactions
- Genetic defects
- Nutritional imbalances
- Physical agents eg trauma or rdiation
- Aging
If a cell adapts by increasing load, what does that lead to?
hypertrophy
What can lead to oxygen deprivation, and therefore cell death?
myocardial infarction
The cellular response to injurious stimuli depends on…
- type of injury
- duration
- severity of injury
The consequences of an injurious stimuli depend on?
- Type of cell
- its states (i.e., where it is during mitosis)
Can bone or brain live longer without O2?
Brain
What are 4 intracellular systems which are particularly vulnerable to cell injury?
- Cell membrane integrity
- ATP generation
- Protein synthesis
- Integrity of genetic apparatus
Is cellular function lost before cell death occurs?
Yes, which in turn occurs before the morphological changes are seen
What is meant by atrophy?
Shrinkage in size of a cell / organ by the loss of cell substance eg shrinking brain in dementia patient
What is an example of atrophy of the brain?
Dementia patient- neurones have atrophied
What is meant by hypertrophy?
Increase in the size of the cells and consequently in the size of the organ as well
Is hypertrophy physiological or pathological?
Both
What causes hypertrophy?
it is caused by increased functional demand or specific hormonal stimulation
What is a pathological example of hypertrophy?
‘Pathological’ cardiac hypertrophy is a condition that is characterised by the thickening of the heart muscle, a decrease in the size of the chambers of the heart, and a reduced capacity of the heart to pump blood to the tissues and organs around the body.
What is an example of physiological hypertrophy?
increase in the size of cells of the uterus during pregnancy to accomodate for the foetus
Can muscle fibres proliferate?
No, so they must expand- aka hypertrophy
What is meant by hyperplasia?
An increase in he number of cells in an organ
Is hyperplasia pathological or physiological?
both
What is the main cause of pathological hyperplasia
usually due to excessive hormonal or growth factor stimulation
What can cause physiological hyperplasia?
hormonal I.e., uterus and oestrogen
Compensatory I.e., in the kidney
Describe a physiological example where hyperplasia can occur?
increased oestrogen stimulation drives the increased proliferation of the endometrial glands leading to increased number of endometrial cells
What is a pathological example of hyperplasia?
carcinoma = too many cells leading to disease
what is metaplasia?
A reversible change in which one adult cell type is replaced by another
Is metaplasia physiological or pathological?
Both
Describe a pathological example of Metaplasia?
Barretts Oesophagus - The oesophagus is normally lined with squamous epithelium cells, acid reflux causes these to change to columnar epithelial cells
Describe a physiological example of metaplasia?
During pregnancy - cervix expands and due to the acid pH of the vagina, the columnar cells becomes squamous
What is meant by dysplasia?
Pre-cancerous cells which show the genetic and cytological features of malignancy but not invading the underlying tissue
Pre-cancerous stage
Why do cells undergoing dysplasia appear darker on a slide?
Due to an increased nuclear:cytoplasm ration
Nuclei become bigger
What are the two forms of light microscopic changes associated with reversible injury?
fatty change and cellular swelling
What type of change are fatty change and cellular swelling examples of?
Degenerative changes
I.e., changes associated with cell and tissue damage
What is a common cause of fatty change?
Alcohol
What might be seen on a film on cells undergoing fatty change?
Accumulation of lipids in the cytoplasm - seen on film as large clear droplets filling the cytoplasm
Which condition is fatty hepatic change usually associated with?
Alcoholic liver disease
What is meant by cellular swelling?
When the cytoskeleton of cells are damaged leading to protein accumulation that results in cell swelling = degenerative changes
What are the two features of alcoholic liver disease?
Fatty change and cellular swelling
What is ballooning degeneration?
A type of cell injury, balloons also caused by alcohol
What is necrosis?
Confluent cell associated with inflammation
What are the four types of necrosis?
- Coagulative necrosis
- Fatty necrosis
- Liquefactive necrosis
- Caseous necrosis
What is meant by coagulative necrosis?
Accidental cell death typically caused by ischaemia or infarction
- structure is still recognisable but the tissue is dead
What might muscle cells which have undergone myocardial infarction look like?
Inflammatory reaction to dead muscle cells results in lots of macrophages, but no nuclei as cells are dead
- example of coagulative necrosis
- dead but fibres are still visible and recognisable
What is liquefactive necrosis?
When the tissue becomes liquefied which results in a transformation of the tissue into a liquid viscous mass
What type of necrosis occurs with an old cerebral infarct?
Liquefactive necrosis
What is caseous necrosis?
A unique form of cell death in which the tissue maintains a cheese like appearance
What is an example of caseous necrosis?
Pulmonary TB
What is fat necrosis?
Condition when damage to area of fat occurs - fat replaced with oily contents of the fat
Which condition is highly associated with fat necrosis?
Acute pancreatitis
Describe the fat necrosis seen in acute pancreatitis?
This is when pancreatic enzymes are activated in the pancreas, rather than the duodenum - results in lipases digesting pancreatic tissue into fatty acids and triglycerides which bind to Ca2+ ions and form salts which precipitate get deposited in the pancreas as white droplets
What is apoptosis?
Programmed cell death
What does necrosis lead to?
It is confluent death (whole area)
Giving rise to secondary inflammation
What are the five causes of apoptosis?
Embryogenesis. (formation and development of embryo)
Deletion of auto-reactive T cells in the thymus.
Hormone-dependent physiological involution.
Cell deletion in proliferating populations.
A variety of mild injurious stimuli that cause irreparable DNA damage that, in turn, triggers cell suicide pathways.
Describe how a cell would undergo apoptosis?
- Cell undergoes injury
- Genetic errors arise from injury
- Attempts are made to repair the error but errors still remain
- Additional injury = Leads to apoptosis
- Cell membrane never breached
- therefore no inflammatory reaction
- therefore, the apoptotic bodies from the breaking down of the cell, are easily cleared by macrophages
- phagocytosis of apoptotic cells and fragments by phagocytes
What happens during necrosis?
Cell membrane stops working and cytoplasm leaks
Enzymatic digestion and leakage of cellular contents
What are the key differences between apoptosis and necrosis?
Apoptosis might by physiological, necrosis is not
Apoptosis is an active, energy dependant process (if no ATP present there is necrosis)
Necrosis is associated with inflammation, apoptosis is not
Why is ATP needed for Apoptosis?
ATP is needed to maintain cell membrane integrity and package apoptotic bodies
What are physiological examples of apoptosis?
Elimination of self reactive T cells
What is necropoptosis?
Programmed cell death associated with inflammation, but ATP is required
What is an example of a cause of necroptosis?
viral infections
How does a cell actually die through necrosis?
Enzymatic digestion and leakage of cellular components = cell membrane loses integrity
How does a cell die through apoptosis?
Phagocytosis of apoptotic bodies and fragments
