How Do We Exactly Adapt to Changes?

in StemSocial9 months ago


Hello everyone, it's Lenny again with another medical article. I chose today's topic because it might be relatable in one way or another for many, either from things happened to them or from things happened around them.

Have you ever wondered how does your body manage to handle various changes that occur to it from various kinds of stress? Well that's exactly what we are going to talk about in this post which is known as Cellular Responses and Adaptations.


Our body cells always tend to live in normal condition or standard environment where they can function properly. Yet cells have the ability to change in themselves so they may adapt to the change or stimuli so they can survive. The changes that might occur to the cell can be in temperature, Ph, or glucose...etc.

Depending on the level of stimuli the cells responds, so if the stimuli was something cell can bear, then t tries to adapt to the changes until this stimuli is removed. But if the stimuli was serious or the cells wasn't able to adapt then that will lead to cell injury which might lead to cell death .

Types of Cellular Responses

Cellular responses are:

  1. Adaptation which includes: hypertrophy, hyperplasia, atrophy, metaplasia.

  2. Injury which might be reversible and the cell will be back normal after it or irreversible which leads to cell death.

  3. Intracellular accumulation and calcification.

  4. Cellular aging


Adaptation is what we are going to go over in this post, and as I mentioned before there different types of cellular adaptations and we will go over them one by one.




Hypertrophy is increase in cell size, it might be due to physiological reasons or to pathological reasons. This increase in cell size will (not mass), and it might occur side by side with hyperplasia in cells that are capable of dividing like skin and might occur alone in cells that aren't capable of dividing like skeletal muscle cells.

Physiological and Pathological causes

Physiological: Have ever wondered how those body builders body go so big like this? Yes, it is exactly what you are thinking of, it is due to hypertrophy which is caused by increase of the workload in addition to stimulation by hormones. Yet you may also notice that there aren't a "super human" well that's because there is a limit for hypertrophy... You can't just keep getting bigger after all.

Pathological: Cardiac hypertrophy in the left ventricle.



Not sure whether I need to include website for these pictures or not to be honest but here source

Hyperplasia is known to be the increased number of cells which leads to increase the mass of the organ or tissue where hyperplasia occurs. As in hypertrophy, it might be physiological or pathological yet the difference is that it can only occur in dividing cells. It might be hormonal induced (growth hormone) or due to increase output from the stem cells.

Physiological and Pathological causes

Physiological: Female breast during lactation and puberty and here it is mainly hormonal induced. And another example is the partial hyperplasia that might occur in liver tissue after resection.

Pathological: Before going to examples here I have to mention that hypertrophy in greatly involved in cancers when it's pathological. Back to examples: Hyperplasia due to excessive hormone simulation like in endometrium and also infection with papillomavirus.


Atrophy is the loss of cell substance (decreased protein synthesis and increased protein degradation), either number or size, which will lead to reduction in the size of cell and subsequently size of the whole organ.

Physiological and Pathological causes

Physiological: In the development of babies many changes occur throughout the whole embryonic development, some tissues, cells, and organs are made while other cells tend to disappear because they are no longer needed or their disappearance is needed for the development of a particular organ. For instance, Thyroglossal duct.

Other obvious example is the uterus after giving birth.

Pathological: There are many reasons so I will just mention two of them. As there is hypertrophy that occurs due to increase in workload then there must by atrophy that occurs to decreased workload. And other reason for atrophy is the cut of blood supply to certain cells and organs which might occur due to various reasons.


Last type of cellular adaptation. Metaplasia is the change of cell type from differentiated cell type to another and it happens due to reprogramming of stem cells so they will just start differentiate in an another way. This change might be because a new cell type is better at dealing with a particular type of stress yet if persistence of the stimuli/stress might lead to an unfortunate cancer transformation, and that explains the hypertrophy that occurs in the respiratory tract of a smoker which increase their risk of developing cancer.

In The End

Our body always try to maintain homeostasis yet it's not always possible when their is serious and powerful injurious or stress which leads to the injury of the cell that might develop to cell death and loss. Got any more examples for cell adaptation? I would love to read them in the comments. Thanks for reading!


  2. Local professor PP slides (Taken from Pathoma too)
  3. Site