Apoptosis pathology medical laboratory' (1).pptx

pathology

1. Apoptosis Prepared by Mohammed Ibrahim Alaghbare Supervisor: prof/Khadija Mahmoud

2. Apoptosis Apoptosis = falling off or dropping off, as that of leaves or petals . Def: Programmed and coordinated cell death. Apoptosis is a pathway of cell death in which cells activate enzymes that degrade the cells’ own nuclear DNA and nuclear and cytoplasmic proteins .

3. Features of Apoptosis Cell size : Reduced (shrinkage). Nucleus : Fragmentation into nucleosome-sized fragment . Plasma membrane : Intact; altered structure especially orientation of lipids . Cellular contents : Intact; may be released in apoptotic bodies. Adjacent inflammation : No. Physiologic role : Often physiologic means of eliminating unwanted cells. pathologic role : pathologic after some forms of cell injury, especially DNA and protein damage.

4. Causes of Apoptosis Physiologic apoptosis Pathological apoptosis

5. Causes of Apoptosis Physiologic apoptosis : During normal development of an organism, some cells die and are replaced by new ones. In mature organisms, highly proliferative and hormone- responsive tissues undergo cycles of proliferation and cell loss that are often determined by the levels of growth factors. In these situations, the cell death is always by apoptosis, ensuring that unwanted cells are eliminated without eliciting potentially harmful inflammation.   In the immune system, apoptosis eliminates excess leukocytes left at the end of immune responses as well as lymphocytes that recognize self-antigens and could cause autoimmune diseases if they were not purged.

6. B. Pathological apoptosis   Apoptosis eliminates cells that are damaged beyond repair. This is seen when there is severe DNA damage, for example, after exposure to radiation and cytotoxic drugs.   The accumulation of misfolded proteins also triggers apoptotic death. Certain infectious agents, particularly some viruses, induce apoptotic death of infected cells

7. Mechanisms of Apoptosis Apoptosis is regulated by biochemical pathways that control the balance of death and survival inducing signals and ultimately the activation of enzymes called caspases . Caspases were so named because they are cysteine proteases that cleave proteins after aspartic acid residues. Activated caspases lead to activation of nucleases that degrade DNA& others enzymes that destroy nucleoproteins & cytoskeletal proteins .

8. Mechanisms of Apoptosis Intrinsic ( mitochondrial) pathway. Extrinsic ( death receptor ) pathway . - Clearance of apoptotic cells.

9. How does cancer cells overcome of apoptosis?

10. Gross The fragments are quickly extruded and phagocyt e without eliciting an inflammatory response, even substantial apoptosis may be histologically undetectable

11. Microscopic