Cell Pathology 4 - Cell Injury Flashcards
What are the two types of cell injury?
- Lethal produces cell death
- Sublethal produces injury not amounting to cell death, which may be reversible or progress to cell death
List the causes of cell injury
- Oxygen deprivation
- Chemical agents
- Infectious agents
- Immunological reactions
- Genetic defects
- Nutritional imbalances
- Physical agents
- Aging
What does the cellular response to injury depend on?
The type of injury, duration and its severity.
What do the consequences of an injurious stimuli depend on?
Depends on the cell type and on its status
Which intracellular systems are particularly vulnerable to cell injury?
- Cell membrane integrity
- ATP generation
- Protein synthesis
- The integrity of genetic apparatus
What is atrophy?
Shrinking of a cell
Give an example of atrophy
Dementia
When does muscle atrophy occur?
It occurs secondary to denervation
What is hypertrophy?
Increase in the size of cell and consequence organs increase in size.
What causes hypertrophy?
Increased cellular demand or hormonal triggers
Give an example of physiological hypertrophy.
The uterus swells during pregnancy
Give an example of pathological hypertrophy.
Myocytes swell due to injury causing cell death, or due to increased load.
What is hyperplasia?
An increase in the number of cells in the organ
What causes hyperplasia?
- Physiological is caused by hormones/may be compensatory
- Pathological hyperplasia is due to excessive hormonal or growth factor production
Give an example of physiological hyperplasia.
Proliferative endometrium (increase in thickness of the lining of the uterus)
Give an example of pathological hyperplasia
Carcinoma
What is metaplasia?
A reversible change where one cell type is replaced with another
Give an example of physiological metaplasia
The lining of the cervix - columnar to squamous and the reverse during puberty.
Give an example of pathological metaplasia
Barrett’s oesophagus - acidosis causes the oesophagus wall to become columnar. Can be reversed.
What is dysplasia?
Precancerous cells which show the genetic and cytological features of malignancy but don’t invade underlying tissue.
What may dysplasia be associated with?
Barrets oesophagus
What are the light microscopic changes associated with reversible injury?
Fatty change and cellular swelling
What is necrosis?
Congruent cell death associated with inflammation
What are the types of necrosis?
- Coagulative necrosis
- Liquefactive necrosis
- Caseous necrosis
- Fat necrosis
What is coagulative necrosis?
Where the cells are dead but can still be seen and recognised.
What is confluent cell death?
Death of many cells that are close together.
What is liquefactive necrosis?
Occurs in the brain - the absence of cells but presence of liquids.
What is caseous necrosis?
Looks like cheese - creamy and oozes out when cut
What is fat necrosis?
This is where lipase is released and this breaks down triglycerides to fatty acids. The fatty acids bind with calcium to form salts, which deposit to form fat necrosis
Give an example of coagulative necrosis
Myocardial infarction - you can recognise the cells
Give an example of a caseous infarct
Pulmonary TB
Give an example of fat necrosis
Acute pancreatitis
What are the possible causes of apoptosis?
- Embryogenesis
- Deletion if autoreactive T cells in the thymus
- Hormone dependent involution
- Mild injurious stimuli that damage DNA
What are the differences between apoptosis and necrosis?
- Necrosis is leakage of cellular contents, while apoptosis involves formation of apoptotic bodies which are phagocytosed
- Apoptosis can be physiological
- Apoptosis requires energy
- Apoptosis is NOT associated with inflammation
What is necroptosis?
- Programmed cell death associated with inflammation
- Has many causes, such as viral infections
