Photo credit: arstechnica.com
Within the human body, billions of cells experience death on a daily basis, each departing in varied circumstances. While some cells may meet an abrupt end due to injury or infections, others may seek a more orderly exit as they age or begin to malfunction, ensuring their remnants are properly removed.
Initially, researchers believed cells had only two fates: accidental death or a meticulously managed demise. However, advancements in cellular biology have unveiled a diverse array of cell death mechanisms over the last two decades. This expanded understanding could pave the way for innovative treatments for a range of health issues, including infections, autoimmune disorders, and cancers.
Michael Overholtzer, a cell biologist affiliated with Memorial Sloan Kettering Cancer Center, notes the complexity, stating that there are now over 20 different classifications for cell death. This depth of insight reflects ongoing studies into how various cell types respond to stress and damage.
Below are notable examples of both established and recently identified modes of cell death.
Unintentional Death: Necrosis
Cells can perish from a variety of detrimental influences, such as injuries, burns, toxic substances, or infections. This unintentional death is categorized as necrosis.
There are several forms of necrosis, each presenting distinct characteristics and consequences. For instance, in cases of gangrene, blood supply deprivation leads to rotting cells. In different scenarios, cells may undergo liquefaction, resulting in yellowish exudates. Tuberculosis can cause lung cells to become soft and white, a phenomenon known as “caseous” necrosis, owing to its cheese-like appearance.
Conversely, all other types of cell death, except necrosis, are regarded as “programmed.” This implies that the cells consciously initiate the process when they are damaged or have outlived their usefulness.
A Controlled Departure: Apoptosis
Programmed cell death can be classified into two primary types: “silent” and “violent,” according to Thirumala-Devi Kanneganti from St. Jude Children’s Research Hospital. Apoptosis, first identified in 1972, exemplifies the silent method. It represents an organized form of cell death that does not elicit an immune response.
This process proves advantageous when cells are either damaged or when their function is no longer required. Apoptosis allows, for example, tadpoles to eliminate their tail cells during transformation into frogs, or enables human embryos to remove the webbing between their fingers.
During apoptosis, the cell shrinks and detaches from its neighboring cells. The nucleus undergoes fragmentation, and its genetic material condenses into smaller groups. The cell membrane forms blisters and eventually breaks apart, allowing neighboring cells to engulf the debris—ensuring a clean and orderly clearance.
Source
arstechnica.com