Cell injury and fate

Question 1

What is the difference between lethal and sublethal cell injury?

Answer 1

Lethal – produces cell death.

Sublethal – produces injury not amounting to cell death. It may be reversible, or it may progress to cell death.

Question 2

What 4 intracellular systems are particularly vulnerable?

Answer 2

1. cell membrane integrity,
2. ATP generation,
3. protein synthesis
4. the integrity of the genetic apparatus

Question 3

What is atrophy?

Answer 3

Atrophy – shrinkage in the size of cell by the loss of cell substance e.g. dementia

Question 4

What is hypertrophy?

Answer 4

Hypertrophy – increase in size of cell and consequently increase in size of organ. Can be physiological (uterus during pregnancy) or pathological (disease). It is caused by increased functional demand or hormonal stimulation. Physiological = normal/enhanced function. Pathological = reduced function.

Question 5

What is hyperplasia?

Answer 5

Hyperplasia – An increase in the number of cells in an organ. Can be physiological or pathological. Physiological hyperplasia can be either hormonal or compensatory. Pathological hyperplasia (e.g. cancers) is usually due to excessive hormonal or growth factor stimulation.

Question 6

What is metaplasia?

Answer 6

Metaplasia – A reversible change in which one adult cell type is replaced by another. Can be pathological or physiological.

Question 7

What is dysplasia?

Answer 7

Dysplasia – Precancerous cells which show the genetic, cytological features or malignancy but does not invade the underlying tissue.

Question 8

What is necrosis?

Answer 8

Confluent cell death associated with inflammation. This is because unlike apoptosis, the cell death is unexpected and therefore causes an inflammatory response.

Question 9

What are the 4 types of necrosis?

Answer 9

1. Coagulative – Inadequate blood supply causes proteins in the cell to break down when the cellular liquid becomes acidified. However, the tissue stays firm and the cells hold their structure resulting in a ghost-like appearance.
2. Liquefactive – Digestion of dead cells forming a viscous liquid mass. Typical of bacterial infections because of their ability to stimulate an inflammatory response. The necrotic liquid mass is creamy yellow due to the presence of dead white blood cells and is commonly known as pus. Hypoxic infarcts in the brain presents this type of necrosis because the brain contains little connective tissue but a lot of digestive enzymes and lipids therefore cells are more readily digested by their own enzymes.
3. Caseous – Typically caused by mycobacteria and fungi. The necrotic tissue appears white and can be considered a combination of coagulative and liquefactive necrosis. Dead cells disintegrate but are not completely digested leaving granular particles.
4. Fat – Specialised necrosis of fat tissue resulting from action of activated lipases on fatty tissues such as the pancreas. In the pancreas it leads to acute pancreatitis, a condition where the pancreatic enzymes leak out and liquefy the membrane by hydrolysing the triglycerides. Ions such as calcium may bind to these lesions and produce a chalky white substance.

Question 10

Difference between apoptosis and necrosis

Answer 10

Apoptosis is doesn’t cause inflammation and is signalled by the cell.