Cells within the human body contain thousands of genes, proteins and other chemicals enclosed within cellular membranes. Each cell responds to chemical signals from the body or the environment and modifies its behavior in response to signals. Cellular diseases occur when cells dysfunction; this may include the development of too many cells, deficiencies in existing cells or dysfunction or loss of essential cells. Cellular diseases vary in severity and the types of cells they affect, sometimes proving fatal.
Cancer is among the most common diseases in the United States: the Cancer Journal for Clinicians indicates that cancer accounted for an estimated 562,340 deaths and 1,479,350 new diagnoses in the United States in 2009. Cancer is used to describe hundreds of diseases, all of which occur when normal cells develop genetic mutations that lead to abnormal cell proliferation, usually leading to the formation of tumors.
At the heart of cancer development are genetic mutations, which lead to changes in cellular behavior that allow the cells to divide uncontrollably. Several treatments for cancers aim to inhibit essential cellular processes to stop cell division and lead to cancer cell death. If left untreated, cancer cells have the ability to migrate throughout the body to form tumors in distant tissues, which can lead to death.
Another common cell disease is sickle-cell disease, a blood disorder characterized by defects in erythrocytes, or red blood cells. Red blood cells contain a molecular complex called hemoglobin, an iron-containing molecule which binds to oxygen and carries it throughout the bloodstream. In sickle-cell disease, the hemoglobin in red blood cells is mutated, so the cells cannot effectively carry oxygen to tissues throughout the body. The mutation also changes the shape of the red blood cell from a rounded shape to sickle shape, further causing problems in the blood.
Patients with sickle-cell disease experience anemia from a lack of sufficient oxygenation of tissues, along with shortness of breath, cold hands and feet and pain, reports the National Heart, Lung and Blood Institute. Sickle-cell disease may require blood transfusions to treat the disease.
Another cellular disease is Alzheimer's, which affects the nerve cells in the brain called neurons. Neurons form a complex network of communication with other nerve cells in the brain, and ultimately transmit signals to the body.
Patients with Alzheimer's disease develop harmful protein aggregates called protein plaques, which disrupt the function of neighboring neurons. The cellular structure of the neuron begins to collapse, creating structures called neurofibrillary tangles that ultimately cause neuron cell death. As a result of progressive neuron loss, patients with Alzheimer's suffer from dementia and memory loss, as well as defects in motor function and personality and behavioral changes. Although Alzheimer's is incurable, a number of drugs can slow the progression of the disease to increase patient quality of life.