The cell, the functional unit of the body, is extremely complex relying on ability to preserve the internal equilibrium by altering its physiological processes. I like to compare a cell to a city; it consists of different components that need to function optimally to ensure that the city is well taken care of and is running smoothly. If the electricity had to go off in the city, it would come to a standstill. Similarly if the mitochondria had to suddenly stop functioning as it should, it would eventually lead to the death of the cell. So what is disease and how will cell death and necrosis affect the body?
Firstly it is important to note that all cells are not the same. Each cell has its own special function and purpose in the body that is decided before birth. They differentiate into epithelial, connective tissue, muscle tissue and nervous tissue cell where they will all have different functional purposes. Each cell will be working towards the same purpose: maintain homeostasis.
To understand disease, one has to understand what homeostasis is. Homeostasis is the ability to maintain a constant internal environment in response to environmental changes (About.com; 2013). Disease is defined as an impairment of the normal state of the living or one of its parts that modify the performance of the vital functions, is typically manifested by distinguishing signs and symptoms, and is a response to environmental factors to specific infectious agents, to inherent defects of the organism, or to combinations of these factors (Marriam-Webster, 2013).
From this I assume that disease is the body’s (by means of specialized cells) reaction to an agent or stressor that interferes with the normal functioning of the cell. The symptoms that one experiences when ill are basically the body’s reaction to bring about homeostasis by achieving internal equilibrium. When the cell is injured, it tries to adapt to minimize the effect of the damage. At this point the damage can be reversed but after more injury it surpasses a point where it can survive resulting in cell death. . Injury can have many effects on the cell causing mitochondrial, endoplasmic reticulum, cell membrane and nucleus damage; this is damage that cannot be reversed.
Necrosis occurs when there is a pathologic death of one or more cells, or of a portion of tissue or organ, resulting from irreversible damage. The earliest irreversible changes are mitochondrial, referring to cloudy and hydropic swelling and granular calcium deposits which inhibit cellular enzyme function and denature proteins.
The most common visible alterations to the nuclei are: pyknosis, shrinking of the nuclei, karyorrhexis which is rupture or split of the nuclear membrane and karyolysis where the basophilia gradually fades. After such changes, the outlines of individual cells are indistinct, and affected cells may merge, sometimes forming a focus of coarsely granular, amorphous, or hyaline material (WebMD, 2013).
There are different types of necrosis; coagulative necrosis which occurs due to ischaemic damage, colliquative necrosis also known as liquifactive necrosis where the cell is hydrolyzed leaving behind a tissue that appears to be semi liquid, suppurative necrosis is associated to bacteria that causes the production of pus, caseous necrosis which is basically the crumbling of tissue that results in the total loss of cell detail, gummatous necrosis caused by spirochetes, fat necrosis consisting of enzymatic and traumatic fat necrosis and lastly gangrenous necrosis which is a putrefactive necrosis.
Gangrenous necrosis consists of dry gangrene, wet gangrene and gas gangrene. Dry gangrene is not a true gangrene as there is no infection but it looks like gangrene, moist gangrene occurs in moist tissues and organs that are infected by saprophytic organisms which cause the tissue to degrade and emit a foul smell. The infected area is smelly, dark and rotten. Gas gangrene occurs due to a bacterial infection that causes gas to form within tissue.
A picture of a patient suffering of gas gangrene
Sometimes cells will undergo a controlled or programmed death which is known as apoptosis. This process could be triggered by an intercellular parasite or cancer. The cell will shrink individually and the cell will then break into pieces.
After learning all this I have discovered that the symptoms of disease are not only caused by pathogenic microorganisms but are the response of the body in order to maintain homeostasis and prevent further disruption in the rest of the body. The body is a complex system that will fight every cell till the end in order to keep it functioning properly, something that I have truly started appreciating.
1. About.com, 2013. Homeostasis. [Online] Available at: http://biology.about.com/od/biologydictionary/g/homeostasis.htm [Accessed 17 February 2013]
2. Marriam-Webster, 2013. Disease. [Online] Available at: http://biology.about.com/od/biologydictionary/g/homeostasis.htm [Accessed 17 February 2013]
3. WebMD, 2013. Necrosis. [Online] Available at: http://dictionary.webmd.com/terms/necrosis [Accessed 17 February]