Cellular Aging and the Integumentary System

It has been interesting to learn about what actually happens to cells as they begin to age. The plasma membrane encounters structural changes. For example, the membrane has less fluidity and this is due to an increase in saturated fats. In the calcium pump, transporters slow down which causes there to be too much calcium in the blood, and not enough in the cell. In the nucleus, there is an increase in DNA damage, a decrease in DNA repair processes which leads to errors in proteins being synthesized, and changes in chromatin. With age, the chromatin becomes more condensed, there is less access for repair enzymes, and there is a decrease in RNA synthesis. There is something in the cytoplasm that inhibits DNA syntheses in older cells. Autophagy is the process used to destroy damaged organelles. Proteins can be broken down by entering a proteosome where it is broken down into amino acids and then released. Finally, in the mitochondria, there is a decrease in the number of post mitotic cells which causes the source of metabolic energy to decrease.

So far, I find the Integumentary System to be very interesting. Part of this may be that all of the material is new to me; but there is just so much going on in our skin that I was unaware of. I would have never thought as our skin to be an organ but it is actually the biggest organ of the body which is composed of all four cell types. The average person's skin in 22 square feet, 1-2 mm thick, and weighs 10 pounds. There are two major layers: the epidermis and the dermis. There are five layers of the epidermis and they include, the Stratum Basale, the Stratum Spinosum, the Stratum Granulosum, the Stratum Lucidum, and the Stratum Corneum.

I decided to find an article that talks about autophagy because I find it to be an amazing process. The article states that autophagy is an homeostatic process where cells break themselves down (Levine et al, 2011). This is an important process with regards to immunity and inflammation. Autophagy occurs because of nutrient deprivation or metabolic stress (Levine et al, 2011). The link to this article is: http://www.nature.com/nature/journal/v469/n7330/full/nature09782.html