CELLULAR ADAPTATIONS

Cellular adaptations are the mechanism by which cells attempt to respond to environmental change. In an intra-cellular or extra-cellular environment, if the homeostatic condition of the cell changes, the cell tries to adapt. This is because, if the cell is unable to adapt to a new environmental condition, its fate will be to go to a damage, or will be damaged by this new situation. The damage can be:

- reversible: the cell can still return to homeostatic conditions 

- irreversible: the cell goes to death 

Cellular adaptations are intended to ensure the survival of the cell and give an appropriate response to new conditions. Thus, a cell can adapt both to survive and to respond appropriately to new exigencies.

There are different types of cellular adaptation, however all adaptations have common characteristics: 

- Reversibility: if a cell is in a new environmental condition it adapts but can return to homeostatic conditions if the condition that induced the adaptation ceases.

- Adaptation conditioned by cell type: different types of cellular adaptation can be enacted by different types of cells. So the type of adaptation that the cell undergoes depends also on the cell type itself (hepatocyte, CNS cell or cardiomyocyte) 

- the capacity of adaptation is not unlimited and when the stress to adaptation is too intense or too prolonged in time, the cell may undergo cellular damage.

 SITUATIONS THAT LEAD TO ADAPTATION

Situations that most frequently lead a cell to adapt. 

Muscle cells adapt by becoming hypertrophic when asked to function more. A condition that very frequently leads to cell adaptation is an increase in functional demand. 

Cells can also adapt if they need to replace cells that have been lost: if a certain amount of cells are lost, those that have survived can adapt to replace them. 

A cell will have to adapt if it finds itself in a situation where it receives less nutrients and less oxygen, because a reduced availability of these affects cell function and primarily decreases it.

Cells can also adapt if a stimulation is decreased or lost, for example, one stimulation is electrical stimulation.

Cells can adapt if for a prolonged time they are in a stressful condition. 

These are therefore the most frequent causes that lead a cell to change and adapt by modulating its functions. 

The situations that can induce a cellular adaptation are of two types:

- Physiological 

- Pathological

From a conceptual point of view, the mechanisms that determine these two types of adaptation are still the same and the change is upstream: a physiological stimulus or a pathological stimulus that induces the cell to adapt. So the mechanisms of the cellular response are always similar but the induction changes.