Cell Injury and Cell Death
“Common biochemical themes are important to understanding cell injury and cell death regardless of the injuring agent” (Heuther & McCance, 2012). Cellular injury arises when a cell is unable to sustain homeostasis. The injury can be reversed if the cell can recover from whatever damage was done but if it does not recover the cell will die. The three common forms of cell injury are hypoxic injury, free radicals and reactive oxygen species injury, and chemical injury.
The most common form of cell injury is hypoxic injury, or hypoxia, the deficiency of adequate oxygen. Ischemia is the most common cause of tissue hypoxia and is caused from a decrease in blood flow. Hypoxia can also be caused by a reduced amount of oxygen in the air, loss of hemoglobin, diseases of the respiratory and cardiovascular systems, and decreased production of red blood cells. Cardiac ischemia is one of the most recognizable forms of hypoxic injury and is caused by a blockage in the coronary arteries of the heart.
Once the blood flow to heart tissue decreases or stops completely, the heart tissue is damaged and can lead to further complications including a myocardial infarction. Another form of cell injury is free radicals and reactive oxygen species. “An important mechanism of cellular injury is injury induced by free radicals, especially by reactive oxygen species (ROS); this form of injury is called oxidative stress” (Heuther and McCance, 2012). Free radicals are produced by cells and are crucial to normal cellular metabolism.
Free radicals can form damaging chemical bonds with lipids, proteins, and carbohydrates. The most commonly defined free radicals are the reactive oxygen species (ROS) which contribute to mitochondrial dysfunction and are linked to many human diseases and the aging process. According to a holistic physician, Dr. Jill Marjama-Lyons, “oxidative stress is one of the leading theories as to what might cause dopamine cell death in Parkinson’s disease” (2003). Chemical injury is the final form of cell injury.
“About 4 billion pounds of toxic chemicals are released per year in the United States. Of these, approximately 72 million pounds are known carcinogens” (Heuther and McCance, 2012). We are frequently exposed to xenobiotics, a variety of compounds that include toxic, mutagenic, and carcinogenic chemicals. “These chemicals can react with cellular macromolecules, such and proteins and DNA, or can react directly with cell structures to cause cell damage” (Heuther and McCance, 2012).
Tissue damage caused by xenobiotics can lead to organ and systemic toxicity, mutations, and cancer. Lead , a heavy metal found in the environment, is a chemical highly toxic to children. The exposure primarily effects the nervous system, the hematopoietic system, and the kidneys. Lead exposure can result in learning disorders, hyperactivity, and attention problems if exposure is too high. Cell injury occurs when a cell is unable to sustain homeostasis. Maintaining homeostasis within the body is vital to prevent serious complications and death. Cell injury forms include hypoxic injury, chemical injury and oxidative stress.
Hypoxia is the insufficiency of oxygen, without oxygen the body cannot keep its tissue healthy and that can lead to tissue death and organ system failure. Unfortunately, due to the 4 billion pounds of toxic chemicals released into the environment each year, chemical injury is common and hard to avoid. Chemicals can be found the air, the food we eat and the water we drink. Exposure and a reaction to the exposure depends on an individual’s health. Cell injury can be reversed but it must happen quickly to prevent lasting complications or cell death.