describe the cellular response to injury and stress. 20mks

Question

Describe the cellular response to injury and stress.                                                20marks

Answer 1

Collectively, you can refer to any injury to the tissue of the body as the inflammatory response.  After the tissue is damaged, you'll get chemotaxis of immune cells into the region using chemotactic chemicals.  For instance, mast cells produce histamine which causes nearby capillaries to vasodilate and become "leaky" allowing other white blood cells to infiltrate the area.  The list of chemicals that can cause chemotaxis is extensive: prostaglandins, kinins, complement, etc.  In addition, damaged cells release substance P, which interacts with neurons to send signals to the brain indicating damage, aka pain.  This allows the brain to mobilize and send signals modifying the behavior of blood vessels, lymphatic organs, etc.  Depending on the type of injury, proteins called fibrins may wall off the damaged tissue to keep the damage from spreading (i.e. a bacterial infection) in a process very similar to blood clotting.  White blood cells that infiltrate the area begin determining the type of damage and either prepare for "battle," in the case of infection, or for clean-up, in the case of physical damage like a cut.  Once the area has been cleared of pathogens and/or cellular debris, the white blood cells exfiltrate the area or die and are phagocytosed by other white blood cells and a series of regenerative chemicals are released to encourage tissue regrowth.  That's where it gets truly complicated as each tissue's regenerative capabilities are different. Some tissues like the liver seem to be able to completely regenerate over time. Others like nervous tissue and skin regenerate with fibrous connective tissue, instead of remaking themselves the way they were before. And the extent of the damage plays a role as well, so other than the basic inflammatory response as a general method for responding to injury, I can't give you any more than that.
Lastly, stress is a complicated process that involved hormonal and nervous feedback about our environment that goes into modifying our body's homeostatic mechanisms.  The ways in which stress does this are more complex than can be easily written here, but a good place to start teasing apart the strings is the hormone cortisol, produced in the adrenal glands.

Answer 2

Hi Christopher,

 

      It depends on the type of injury and stress as well as the cell type. Cells would synthesize new proteins and transcribe new mRNAs that they may need to repair the injury or combat the stress. Along with pathological changes in cellular morphology and physiological milieu of the particular cell type, there would molecular and epigenetic alterations as well. Cellular response would be variable depending on multiple factors. Let me know what cell types you are looking for and I can provide you more specific answer.

 

    Meanwhile I hope this helps.

 

Thank you Christopher, in somatic cells, cellular injury leads to necrosis and apoptosis, intracellular accumulations, pathological calcifications and cellular aging. It can finally lead to cell death as well if the injury is severe. Harmful cellular stress causes cell injury. Cells experiencing stress undergo adaptation, achieve a new steady state and try to preserve their function and viability.  Adaptive response of cells to injury includes hypertrophy and atrophy. Cellular injury to certain extent  is reversible, cells return to their normal baseline condition when injury ceases. However, persistent and severe injury leads to cell death; that is the significant event leading to disease and at times irreversible pathological condition.  For example, myocardium may be reversibly injured due to brief or  incomplete arterial occlusion; however, it would be irreversibly damaged due to complete or  prolonged occlusion.

 

I hope this helps.