Basic pathology

Cells can be damaged by damaged by various processes including
- Reduced oxygen supply
- Physical agents
- Chemical agents
- Toxins
- Viruses
- Abnormal immunological reactions
Necrosis results from cell death
Results in disintegration of nucleus, cytoplasmic organelles and the plasma membrane
Intracellular enzymes are released
Necrosis is associated with visible changes
- Coagulative necrosis
- Colliquative necrosis
In coagulative necrosis
- Nucleus fades and dissolves (karyolysis)
- Nucleus becomes more dense (pyknosis)
- Nucleus fragments (karyorrhexis)

Apoptosis is programmed cell death
A physiological process
Affects single cells in populations of healthy cells
Mechanism of of removing effete and abnormal cells
Normal cells divide to replace lost cells
No evidence of inflammation
Provides a balance between cell proliferation and elimination
It is associated with:
- Maintenance of organ size in adults
- Organ development in the embryo
- Physiological atrophy and involution

Local deposits of calcium may occur when
- Necrotic tissue is not absorbed
- Tissues undergo slow degeneration

Occurs when serum calcium is elevated for a long period of time
Associated with:
- Increased calcium absorption due to high vitamin D levels
- Resorption of bone
- Mobilisation of calcium due to PTH excess
- Chronic renal failure
Calcium is deposited in:
- Arterial walls
- Kidneys
- Lungs
- Stomach wall