Apoptosis

 

APOPTOSIS 

*Apoptosis is the pathway of genetically intra cellular programmed cell death (cell suicide) in which unwanted host cells are eliminated  by activation of intrinsic enzymes that degrade cell’s own DNA,Nuclear &cytoplasmic proteins

* Apoptosis always present physiologic & pathological condition.

*absence of survival factor /Absence of getting signal to cell;so cell size is decrease and containing apoptic bodies.

*In apoptosis no inflammation is present.

Causes of apoptosis:-

Apoptosis always present in pathological & physiological situations.

Apoptosis in physiologic situation

1)    Development of embryogenesis :-

·         During embryo which includes implantation, organogenesis, metamorphosis etc.

·         during all these stage of development ;lots of cells are known unneeded, and they die via apoptosis in programmed manner.

 2)Harmone- dependent apoptosis tissue:-

Eg- When mother stopped breast feeding to her child.then lactin harmone reduces the breast size and return back to their normal previous size that occur by apoptosis.

 3)Cell population:-

Apoptosis is the very common phenomena in multicellular organism. When the number of cell is very high then apoptosis occuring and reducing the no. of cells and maintain it.

Eg- replacement proliferation such as in intestinal epithelium

4)   Elimination of blood cells after they have performed their role during their life span.

5)   loss of immature B& T cells in the bone marrow and thymus by clonal deletion & cytotoxicity

Apoptosis in pathologic situation

1)    Damage  to host cell DNA:-

Eg-  Chemotherapy in treatment of cancer irradiation by therpy performed mild thermal injury or Hypoxia.

2)    Endoplasmic stress:-

It’s due to accumulation of large excess of misfolded pattern formed by free redical injury or from mutations

3)    Certain viral Infection:-

Exp- council man bodies in viral hepatitis,

Progressive depletion of CD4 + T cells in HIV infection.

Cell death by cytotoxic T cell in transplant refection reaction