Cell injury Flashcards
List the EIGHT causes of cell injury
Oxygen deprivation Inflammation Chemical Agents Genetics Infection Nutritional imbalances Physical Agents Ageing
oxygen is crucial in going around north pole
What four intracellular mechanisms are particularly vulnerable to cell injury?
- Cell membrane integrity
- Protein synthesis
- ATP Generation
- Integrity of the genetic apparatus
Define Atrophy.
Shrinking in the size of a cell or organ by the loss of cell substance.
Define Hypertrophy.
examples of causes?
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
eg. cardiomyocytes adaptation to increased stress is hypertrophy
Define Hyperplasia
Increase in the number of cells in an organ
Can be physiological or pathological
eg. cancer = pathological hyperplasia
Define Metaplasia
A REVERSIBLE change in which one adult cell type is replaced with another
eg. barretts oesophagus
Define Dysplasia.
name a screening which identifies this?
what is the relation between metaplasia and dysplasia?
Pre-cancerous cells which show the genetic and cytological features of malignancy but not invading the underlying tissue
- cervical cancer screening
- normally metaplasia leads onto dysplasia
Define Ulcer.
A local defect, or excavation of the surface, of an organ or tissue, produced by sloughing of necrotic inflammatory tissue
What are the two physiological causes of hyperplasia?
Hormonal (e.g. oestrogenic wave of proliferation)
Compensatory
What are two light microscopic changes associated with reversible injury?
Fatty change
Cellular swelling
these are degenerative
Define Necrosis
Confluent cell death associated with inflammation
whole areas of cells die
What are the four types of necrosis?
Coagulative,
Liquefactive,
caseous
Fat
What disease is fat necrosis associated with and why?
Acute pancreatitis -
- release of lipases that break down triglycerides into free fatty acids and glycerol.
- Free fatty acids associate with calcium deposits
- each deposit is an area of fat necrosis
Describe some uses of apoptosis
- Embryogenesis - lumen of intestine is created by the apoptosis of the cells
- Removal of auto-reactive T and B cells
- Cell deletion in proliferating populations
- Hormone dependent physiological involution - e.g. shedding of endometrium
Describe three differences between apoptosis and necrosis.
- Apoptosis is an active process (required energy)
- Apoptosis can be physiological
- Apoptosis is not associated with inflammation
what does the cellular response to the injury depend on?
- type of injury
- duration
- severity
why is the cell membrane important?
- the cell membrane distinguishes the self form non self
what does trophy mean?
what does plasia mean?
trophy = size plasia = number
what is coagulative necrosis?
- The substance changes but the shape of the molecule DOES NOT change
- eg all the nuclei disappear
what is Liquefactive Necrosis?
- when all the cells liquify
- eg the brain might liquify
what is Caseous Necrosis
- ‘Cheesy’ necrosis
- Associated with Pulmonary TB
- The necrotic area is GRANULAR
what is the purpose of apoptosis ?
- If the cell can repair itself it will
- If the injury is too severe or the repair systems are lacking
- When a cell recognises that it can’t repair itself, it goes for apoptosis
what is apoptosis ?
- death of single cells
- there is no inflammation
- active cell death
- apoptosis is a neat process
- The nucleus shrinks and little bits of the
cell break off - NO
INFLAMMATION - phagocytosed by macrophages
